CLASSES

Anticonvulsants, Miscellaneous

BOXED WARNING

Due to life-threatening serious rash (including Stevens-Johnson syndrome and toxic epidermal necrolysis), lamotrigine carries a boxed warning stating the drug should be discontinued if rash occurs at any time during treatment. It is important to note that discontinuation of lamotrigine may not prevent progression to a higher level of severity; therefore patients should be closely monitored. Age is the only factor currently known to predict the occurrence or severity of a rash, with pediatric patients at increased risk (see pediatric patients precaution). Other possible but unproven factors include concurrent use of valproate, exceeding the initial recommended dose, or exceeding the recommended dose titration. Almost all cases of life-threatening rash have occurred within the first 2—8 weeks of treatment. However, a prolonged duration of therapy should not preclude the possibility of an association to the drug. Also, caution is advised when administering lamotrigine to patients with a history of rash or allergy to other anticonvulsants, since non-serious rashes have occurred 3 times more frequently in these patients during treatment with lamotrigine than in those without this history. Lamotrigine should not be resumed following prior discontinuation due to rash unless the benefits outweigh the risks. If the drug is reintroduced and it has been 5 half-lives or longer since the last dose, the manufacturer recommends reinitiating using initial dosing recommendations.

DEA CLASS

Rx

DESCRIPTION

Oral anticonvulsant agent derived from agents which inhibit dihydrofolate reductase, although lamotrigine has relatively little antifolate activity.
Adjunctive treatment for refractory partial seizures; monotherapy or adjunctive therapy of partial seizures; adjunct treatment of Lennox-Gastaut syndrome or primary generalized tonic-clonic seizures; effective for maintenance treatment of bipolar I disorder.
Discontinue the drug if a rash appears at any time during treatment; monitor for emerging or worsening suicidal thoughts or unusual changes in moods or behaviors.

COMMON BRAND NAMES

Lamictal, Lamictal CD, Lamictal ODT, Lamictal XR

HOW SUPPLIED

Lamictal CD/Lamotrigine Oral Tab Chew: 5mg, 25mg
Lamictal ODT/Lamotrigine Oral Tab Orally Dis: 25mg, 50mg, 100mg, 200mg, 25-50mg, 25-50-100mg, 50-100mg
Lamictal XR/Lamotrigine Oral Tab ER: 25mg, 50mg, 100mg, 200mg, 250mg, 300mg, 25-50mg, 25-50-100mg, 50-100-200mg
Lamictal/Lamotrigine Oral Tab: 25mg, 100mg, 150mg, 200mg, 25-100mg

DOSAGE & INDICATIONS

†Indicates off-label use

MAXIMUM DOSAGE

In seizure disorders, individualize to the patient's age, weight, indication, concurrent medication, and clinical response. In bipolar disorder, maximum monotherapy dosage is 200 mg/day PO; 100 mg/day PO if taking valproate; 400 mg/day PO if taking enzyme-inducing drugs.

In seizure disorders, individualize to the patient's age, weight, indication, concurrent medication, and clinical response. In bipolar disorder, maximum monotherapy dosage is 200 mg/day PO; 100 mg/day PO if taking valproate; 400 mg/day PO if taking enzyme-inducing drugs.

In seizure disorders, individualize to the patient's age, weight, indication, concurrent medication, and clinical response. Safe and effective use in bipolar disorder has not been established.

>= 2 years: In seizure disorders, individualize to the patient's age, weight, indication, concurrent medication, and clinical response. Safe and effective use in bipolar disorder has not been established. Safe and effective use of extended-release formulation has not been established. Guidelines: Children receiving valproate: 200 mg/day PO as adjunct treatment. Children receiving enzyme-inducing AEDs (e.g., carbamazepine, phenobarbital, phenytoin, primidone) WITHOUT valproate: 400 mg/day PO as adjunct treatment. Children receiving AEDs OTHER than carbamazepine, phenobarbital, phenytoin, primidone, or valproate: 300 mg/day PO as adjunct treatment.
< 2 years: Safety and efficacy have not been established.

DOSING CONSIDERATIONS

Initial, escalation, and maintenance doses should generally be reduced by 25% in patients with moderate hepatic impairment or severe impairment without ascites, and by 50% in patients with severe hepatic impairment with ascites. Adjust doses as needed according to clinical response.

Dosage should be modified depending on clinical response and degree of renal impairment. A reduced maintenance dosage may be effective, but due to limited experience, no quantitative recommendations are available.
 
Intermittent hemodialysis
Hemodialysis lowers the apparent elimination half-life of lamotrigine by 70% to 80%. The half-life decreases from 43 to 57 hours in anuric subjects between dialysis treatments to 13 hours during dialysis treatments. Approximately 20% of lamotrigine present in the body is removed after a standard 4-hour dialysis session. No quantitative recommendations are available for adjustments.

ADMINISTRATION

NOTE: Medication errors have been reported with lamotrigine starter kits. Mild to severe side effects, including Stevens-Johnson Syndrome have occurred. There are 3 different starter kits with titration schedules dependant on concurrent medications (see below). Patients must receive the correct kit to avoid over or under dosing.
 
A MedGuide is available that discusses the risk of suicidal thoughts and behaviors associated with the use of anticonvulsant medications.

STORAGE

Lamictal:
- Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
Lamictal CD:
- Protect from light
- Store at controlled room temperature (between 68 and 77 degrees F)
- Store in a dry place
Lamictal ODT:
- Store at controlled room temperature (between 68 and 77 degrees F)
Lamictal XR:
- Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F

CONTRAINDICATIONS / PRECAUTIONS

Lamotrigine is contraindicated in any patient who exhibits or is suspected of having a lamotrigine hypersensitivity or hypersensitivity to any components of its formulation.
 
Lamotrigine has been reported to interfere with the assay used in some rapid urine drug screens. This interference can result in false-positive readings, particularly for phencyclidine (PCP). To confirm a positive result, a more specific analytical method should be used. 

Due to life-threatening serious rash (including Stevens-Johnson syndrome and toxic epidermal necrolysis), lamotrigine carries a boxed warning stating the drug should be discontinued if rash occurs at any time during treatment. It is important to note that discontinuation of lamotrigine may not prevent progression to a higher level of severity; therefore patients should be closely monitored. Age is the only factor currently known to predict the occurrence or severity of a rash, with pediatric patients at increased risk (see pediatric patients precaution). Other possible but unproven factors include concurrent use of valproate, exceeding the initial recommended dose, or exceeding the recommended dose titration. Almost all cases of life-threatening rash have occurred within the first 2—8 weeks of treatment. However, a prolonged duration of therapy should not preclude the possibility of an association to the drug. Also, caution is advised when administering lamotrigine to patients with a history of rash or allergy to other anticonvulsants, since non-serious rashes have occurred 3 times more frequently in these patients during treatment with lamotrigine than in those without this history. Lamotrigine should not be resumed following prior discontinuation due to rash unless the benefits outweigh the risks. If the drug is reintroduced and it has been 5 half-lives or longer since the last dose, the manufacturer recommends reinitiating using initial dosing recommendations.

In January 2008, the FDA alerted healthcare professionals of an increased risk of suicidal ideation and behavior in patients receiving anticonvulsants to treat epilepsy, psychiatric disorders, or other conditions (e.g., migraine, neuropathic pain). This alert followed an initial request by the FDA in March 2005 for manufacturers of marketed anticonvulsants to provide data from existing controlled clinical trials for analysis. Prior to this request, preliminary evidence had suggested a possible link between anticonvulsant use and suicidality. The primary analysis consisted of 199 placebo-controlled clinical studies with a total of 27,863 patients in drug treatment groups and 16,029 patients in placebo groups (>= 5 years of age). There were 4 completed suicides among patients in drug treatment groups versus none in the placebo groups. Patients receiving anticonvulsants had approximately twice the risk of suicidal behavior or ideation as patients receiving placebo (0.43% vs. 0.24%, respectively; RR 1.8, 95% CI: 1.2—2.7). The relative risk for suicidality was higher in patients with epilepsy compared to those with other conditions; however, the absolute risk differences were similar in trials for epilepsy and psychiatric indications. Age was not a determining factor. The increased risk of suicidal ideation and behavior was observed between 1 and 24 weeks after therapy initiation. However, a longer duration of therapy should not preclude the possibility of an association to the drug since most studies included in the analysis did not continue beyond 24 weeks. Data were analyzed from drugs with adequately designed clinical trials including carbamazepine, felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tiagabine, topiramate, valproate, and zonisamide. However, this is considered to be a class effect. All patients beginning treatment with anticonvulsants or currently receiving lamotrigine should be closely monitored for emerging or worsening depression or suicidal thoughts/behavior. Patients and caregivers should be informed of the increased risk of suicidal thoughts and behaviors and should be advised to immediately report the emergence or worsening of depression, the emergence of suicidal thoughts or behavior, thoughts of self-harm, or other unusual changes in mood or behavior. Anticonvulsants should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose.

Patients receiving lamotrigine for any indication, including bipolar disorder, should not undergo abrupt discontinuation if possible due to the potential for withdrawal seizures. A gradual taper of lamotrigine over 2 weeks is recommended unless safety concerns require a more rapid discontinuation.

Lamotrigine commonly causes blurred vision, dizziness, and drowsiness. Patients should be advised to use caution when driving or operating machinery, or performing other tasks that require mental alertness until they are aware of whether lamotrigine adversely affects their mental and/or motor performance.

Lamotrigine should be used with caution in patients with hepatic disease or impairment because the drug is extensively metabolized by the liver. Animal data reveal that the 2-N-methyl metabolite causes prolongation of the PR interval, widening of the QRS complex, and, at higher doses, complete AV conduction block. This is not expected to occur in humans because only trace amounts of this metabolite is found, however, in patients with hepatic disease, it is possible that concentrations of the 2-N-methyl metabolite might be increased due to decreased glucuronidation. Pharmacokinetic studies have shown that the apparent clearance of the drug is reduced and the half-life is prolonged in those with mild to severe hepatic impairment. The half-life is prolonged as much as 100 +/- 48 hours in those with severe hepatic impairment and ascites compared to 33 +/- 7 hours in healthy controls. Dosing alterations are suggested in patients with moderate to severe hepatic impairment (see Dosage).

Lamotrigine should be used with caution in patients with severe renal disease, renal impairment, or renal failure, including patients on dialysis. Initial doses of lamotrigine should be based on the patient's current antiepileptic drug regimen. Reduced maintenance doses of lamotrigine may be effective in maintaining seizure control. In one study of patients with chronic renal failure, the mean plasma half-life of lamotrigine was 42.9 hours, compared to 26.2 hours in healthy volunteers. During hemodialysis sessions the mean plasma half-life was 13 hours, and 57.4 hours between hemodialysis (manufacturer's data).

The manufacturer of lamotrigine recommends that caution also be used in patients with cardiac function impairment (e.g. heart failure, cardiac disease) since the metabolism or elimination of the drug could be affected (see details under hepatic disease, renal disease and impairment).

In specific patient populations lamotrigine dosage adjustment may be necessary. Oral clearance of lamotrigine in noncaucasians (e.g., black patients) is 25% lower than in Caucasians.

Clinical studies of lamotrigine for epilepsy and for bipolar disorder did not include sufficient numbers of geriatric subjects 65 years of age or older to determine whether they respond differently or exhibit a different safety profile than younger adults. Geriatric patients exhibit a lower clearance and longer lamotrigine half-life when compared to young adults. It is recommended that older adults receive dosages at the low end of the normal adult range. Liver and kidney function should be assessed in the geriatric patient prior to lamotrigine initiation since dosages should be adjusted for organ function impairments.. According to the Beers Criteria, anticonvulsants are considered potentially inappropriate medications (PIMs) in geriatric patients with a history of falls or fractures and should be avoided in these patient populations, with the exception of treating seizure and mood disorders, since anticonvulsants can produce ataxia, impaired psychomotor function, syncope, and additional falls. If lamotrigine must be used, consider reducing use of other CNS-active medications that increase the risk of falls and fractures and implement other strategies to reduce fall risk. The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities. According to the OBRA guidelines, some anticonvulsants may be used to treat disorders other than seizures (e.g., bipolar disorder, schizoaffective disorder, chronic neuropathic pain, migraine prevention). The need for indefinite continuation in treating any condition should be based on confirmation of the condition and its potential cause(s). Determining effectiveness and tolerability through evaluation of symptoms should be used to adjust doses. Therapeutic drug monitoring is not required or available for most anticonvulsants. In addition, significant signs and symptoms of toxicity can occur at normal or low serum concentrations, and symptom control for seizures or behavior can occur at subtherapeutic serum concentrations. Obtaining serum medication concentrations may assist in identifying toxicity. High or toxic serum concentrations should become a consideration for dosage adjustments. Anticonvulsants may cause liver dysfunction, blood dyscrasias, and serious skin rashes requiring treatment discontinuation. Anticonvulsants may also cause nausea/vomiting, dizziness, ataxia, somnolence/lethargy, incoordination, blurred or double vision, restlessness, toxic encephalopathy, anorexia, and headaches; these effects can increase the risk for falls. When an anticonvulsant is being used to manage behavior, stabilize mood, or treat a psychiatric disorder, the facility should attempt periodic tapering of the medication or provide documentation of medical necessity in accordance with OBRA guidelines.

Lamotrigine is not indicated for use in the adjunctive treatment of epilepsy in neonates, infants, and children less than 2 years of age. A clinical trial evaluating the use of lamotrigine in partial seizures in pediatric patients aged 1 to 24 months of age was stopped early because the incidence of infectious (37% for lamotrigine and 5% for placebo) and respiratory (26% lamotrigine and 5% placebo) adverse reactions were significantly higher. Safe and effective use of lamotrigine in treatment of pediatric bipolar disorder has not been established. Lamotrigine is associated with a potentially life-threatening serious rash, the incidence of which is higher in pediatric patients than adults. The incidence of serious rash is approximately 0.3 to 0.8% in pediatric patients (2 to 17 years of age) compared to 0.08 to 0.3% in adults. In a prospective cohort study of 1983 pediatric patients receiving adjunctive lamotrigine for epilepsy, there was 1 rash-related death.

Lamotrigine is classified as FDA pregnancy risk category C. There are no adequate and well-controlled studies of pregnant women receiving lamotrigine, and the effects of lamotrigine during pregnancy, labor, or delivery are not fully known; use only if potential benefit justifies the potential fetal risk. Use lamotrigine cautiously in those patients with folate deficiency, as in vitro data reveal that lamotrigine inhibits dihydrofolate reductase, and animal data show that lamotrigine decreased fetal, placental, and maternal folate concentrations. Significant reductions in folate concentrations are associated with teratogenesis (e.g., neural tube defects) and sufficient dietary supplementation with folic acid is recommended during pregnancy to keep folate concentrations at normal ranges. An increased risk of cleft lip or cleft palate may exist when lamotrigine is used during early pregnancy, although the FDA advises that this risk remains uncertain. The FDA also cautions that the number of cases of cleft palate reported with newer antiepileptic drugs (AEDs) is not sufficient to provide a comparison among agents. Untreated seizure or bipolar disorders may also pose health risks to the expectant mother and fetus. As with other AEDs, physiological changes during pregnancy may affect lamotrigine concentrations and/or therapeutic effect. There have been reports of decreased lamotrigine concentrations during pregnancy and restoration of pre-partum concentrations after delivery. Dosage adjustments may be necessary to maintain clinical response. Physicians are advised to recommend that pregnant patients receiving lamotrigine enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry to provide information about the effects of in utero exposure to the drug. Patients must call 1-888-233-2334 to enroll in the registry. Physicians may enroll patients in the Lamotrigine Pregnancy Registry prior to any prenatal diagnostic tests and before fetal outcomes are known by calling 1-800-336-2176. Some supportive epidemiologic data are available. Of 564 infants born to women registered in the North American Antiepileptic Drug Pregnancy Registry and who received lamotrigine as monotherapy in the first trimester of pregnancy, 15 had a major malformation (2.6%, 95% CI 1.5—4.3), which was defined as structural abnormalities with surgical, medical, or cosmetic importance. In contrast, the rate in an unexposed comparison group was 1.62% (95% CI 1—2.7). Five of the 15 infants with a major malformation had non-syndromic oral clefts; 3 had isolated cleft palate and 2 had isolated cleft lip. The incidence rate of 8.9 per 1000 is dramatically higher than the rate of 0.37 per 1000 in the unexposed comparison group. As of June 2006, the manufacturer of lamotrigine is aware of 4 additional cases of oral clefts that were identified in 6 other pregnancy registries that include more than 2000 women exposed to lamotrigine monotherapy in the first trimester. Results from a prospective, multi-center, long-term, observational study of fetal death and malformations during in utero exposure to phenytoin, carbamazepine, lamotrigine, or valproate suggest that valproate poses the greatest risk for serious adverse outcomes. Enrollment was limited to pregnant women receiving monotherapy with one of the four agents for epilepsy. The outcomes of 333 infants were analyzed. The total percentages of serious adverse outcomes (fetal death or congenital malformations) were as follows: lamotrigine 1%, carbamazepine 8.2%, phenytoin 10.7%, and valproate 20.3%. Fetal deaths occurred in 3.6% of the carbamazepine and phenytoin groups, 2.9% of the valproate group, and no deaths occurred with lamotrigine. Congenital malformations were reported as follows: lamotrigine 1% (ventricular septal defect), carbamazepine 4.5%, phenytoin 7.1%, and valproate 17.4%.

According to the manufacturer, lamotrigine is distributed into human breast milk and caution is recommended if lamotrigine is continued during breast-feeding. Patients who intend to breastfeed should be informed that the drug is present in breast milk and that they should monitor their child for potential adverse effects of this drug; the health care provider should discuss the individual benefits and risks with the patient. Because there is the potential for therapeutic serum concentrations in the nursing infant, the American Academy of Pediatrics (AAP) classifies lamotrigine as a drug for which the potential effects on a nursing infant are unknown but may be of concern. Various small studies have demonstrated that lamotrigine plasma concentrations in nursing infants may be as high as 50% of maternal serum concentrations. In one study, the median milk/maternal plasma concentration ratio was 0.61 (range, 0.47—0.77) two to three weeks after delivery. The median lamotrigine plasma concentration in the neonates was approximately 30% (range, 23—50%) of the mother's plasma concentrations. Nursing neonates and young infants are at risk for high serum concentrations, as mothers who had lamotrigine dose increases during pregnancy without subsequent dose decreases following delivery may have elevated serum and milk concentrations. Immaturity of infant glucuronidation capacity necessary for lamotrigine clearance may also lead to greater drug exposure. Apnea, drowsiness, and poor sucking have been reported in nursing infants of mothers using lamotrigine; drug causality is not established. Closely monitor nursing infants for adverse events and perform infant serum concentration measurements if toxicity concerns develop. Discontinue breast-feeding in any infant that develops lamotrigine toxicity. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.

ADVERSE REACTIONS

suicidal ideation / Delayed / 0.1-5.0
peptic ulcer / Delayed / 2.1-4.9
visual impairment / Early / 2.0-4.9
bronchospasm / Rapid / 2.0-2.0
hematemesis / Delayed / 0-0.1
uveitis / Delayed / 0-0.1
Stevens-Johnson syndrome / Delayed / 0-0.1
exfoliative dermatitis / Delayed / 0-0.1
angioedema / Rapid / 0-0.1
toxic epidermal necrolysis / Delayed / 0-0.1
erythema multiforme / Delayed / 0-0.1
renal failure (unspecified) / Delayed / 0-0.1
epididymitis / Delayed / 0-0.1
vasculitis / Delayed / Incidence not known
rhabdomyolysis / Delayed / Incidence not known
apnea / Delayed / Incidence not known
lupus-like symptoms / Delayed / Incidence not known
pancreatitis / Delayed / Incidence not known
disseminated intravascular coagulation (DIC) / Delayed / Incidence not known
hepatic failure / Delayed / Incidence not known
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) / Delayed / Incidence not known
myocarditis / Delayed / Incidence not known
aplastic anemia / Delayed / Incidence not known
red cell aplasia / Delayed / Incidence not known
pancytopenia / Delayed / Incidence not known
hemolytic anemia / Delayed / Incidence not known
agranulocytosis / Delayed / Incidence not known
aseptic meningitis / Delayed / Incidence not known

blurred vision / Early / 4.0-25.0
ataxia / Delayed / 2.0-11.0
chest pain (unspecified) / Early / 5.0-5.0
constipation / Delayed / 2.0-5.0
contact dermatitis / Delayed / 2.1-5.0
depression / Delayed / 0.1-4.9
migraine / Early / 1.1-4.9
nystagmus / Delayed / 2.0-4.9
amnesia / Delayed / 1.1-4.9
hyperreflexia / Delayed / 2.1-4.9
peripheral edema / Delayed / 2.1-4.9
edema / Delayed / 1.1-4.9
dyspnea / Early / 2.1-4.9
vaginitis / Delayed / 4.0-4.0
hot flashes / Early / 0.1-2.0
lymphadenopathy / Delayed / 2.0-2.0
atopic dermatitis / Delayed / 2.0-2.0
hallucinations / Early / 0.1-1.0
aphasia / Delayed / 0.1-1.0
memory impairment / Delayed / 0.1-1.0
dyskinesia / Delayed / 0.1-1.0
hypertonia / Delayed / 0.1-1.0
akathisia / Delayed / 0.1-1.0
hostility / Early / 0.1-1.0
psychosis / Early / 0.1-1.0
dysarthria / Delayed / 0.1-1.0
euphoria / Early / 0.1-1.0
hypertension / Early / 0.1-1.0
palpitations / Early / 0.1-1.0
sinus tachycardia / Rapid / 0.1-1.0
peripheral vasodilation / Rapid / 0.1-1.0
orthostatic hypotension / Delayed / 0.1-1.0
myasthenia / Delayed / 0.1-1.0
dysphagia / Delayed / 0.1-1.0
elevated hepatic enzymes / Delayed / 0.1-1.0
gastritis / Delayed / 0.1-1.0
photophobia / Early / 0.1-1.0
conjunctivitis / Delayed / 0.1-1.0
leukopenia / Delayed / 0.1-1.0
impotence (erectile dysfunction) / Delayed / 0.1-1.0
hematuria / Delayed / 0.1-1.0
ejaculation dysfunction / Delayed / 0.1-1.0
urinary incontinence / Early / 0.1-1.0
neuritis / Delayed / 0-0.1
dystonic reaction / Delayed / 0-0.1
dysphoria / Early / 0-0.1
delirium / Early / 0-0.1
hyperalgesia / Delayed / 0-0.1
hyperesthesia / Delayed / 0-0.1
choreoathetosis / Delayed / 0-0.1
hypotonia / Delayed / 0-0.1
hepatitis / Delayed / 0-0.1
melena / Delayed / 0-0.1
colitis / Delayed / 0-0.1
stomatitis / Delayed / 0-0.1
glossitis / Early / 0-0.1
erythema / Early / 0-0.1
eosinophilia / Delayed / 0-0.1
anemia / Delayed / 0-0.1
lymphocytosis / Delayed / 0-0.1
thrombocytopenia / Delayed / 0-0.1
dysuria / Early / 0-0.1
urinary retention / Early / 0-0.1
cystitis / Delayed / 0-0.1
hyperbilirubinemia / Delayed / 0-0.1
hypothyroidism / Delayed / 0-0.1
hyperglycemia / Delayed / 0-0.1
goiter / Delayed / 0-0.1
mania / Early / 5.0
confusion / Early / 1.0
amblyopia / Delayed / 1.0
esophagitis / Delayed / Incidence not known
neutropenia / Delayed / Incidence not known
hyponatremia / Delayed / Incidence not known

diplopia / Early / 5.0-49.0
vomiting / Early / 5.0-20.0
drowsiness / Early / 5.0-17.0
fever / Early / 1.1-15.0
dizziness / Early / 5.0-14.0
pharyngitis / Delayed / 5.0-14.0
nausea / Early / 7.0-14.0
rash / Early / 7.0-14.0
diarrhea / Early / 5.0-11.0
tremor / Early / 4.0-10.0
abdominal pain / Early / 5.0-10.0
asthenia / Delayed / 2.1-8.0
fatigue / Early / 6.0-8.0
back pain / Delayed / 8.0-8.0
cough / Delayed / 5.0-7.0
dyspepsia / Early / 2.0-7.0
dysmenorrhea / Delayed / 5.0-7.0
xerostomia / Early / 2.0-6.0
weight loss / Delayed / 5.0-5.0
diaphoresis / Early / 2.1-4.9
libido increase / Delayed / 2.1-4.9
agitation / Early / 1.1-4.9
irritability / Delayed / 2.1-4.9
emotional lability / Early / 1.1-4.9
hypoesthesia / Delayed / 1.1-4.9
hyporeflexia / Delayed / 2.1-4.9
arthralgia / Delayed / 1.1-4.9
myalgia / Early / 1.1-4.9
sinusitis / Delayed / 1.1-4.9
epistaxis / Delayed / 2.0-4.9
flatulence / Early / 1.1-4.9
weight gain / Delayed / 1.1-4.9
anorexia / Delayed / 2.0-4.9
increased urinary frequency / Early / 1.1-4.9
xerosis / Delayed / 2.1-4.9
vertigo / Early / 2.0-3.0
amenorrhea / Delayed / 2.0-2.0
libido decrease / Delayed / 0.1-1.0
hyperkinesis / Delayed / 0.1-1.0
malaise / Early / 0.1-1.0
paranoia / Early / 0.1-1.0
flushing / Rapid / 0.1-1.0
syncope / Early / 0.1-1.0
yawning / Early / 0.1-1.0
eructation / Early / 0.1-1.0
hypersalivation / Early / 0.1-1.0
gingivitis / Delayed / 0.1-1.0
appetite stimulation / Delayed / 0.1-1.0
tinnitus / Delayed / 0.1-1.0
urticaria / Rapid / 0.1-1.0
ecchymosis / Delayed / 0.1-1.0
menorrhagia / Delayed / 0.1-1.0
polyuria / Early / 0.1-1.0
acne vulgaris / Delayed / 0.1-1.0
alopecia / Delayed / 0.1-1.0
hirsutism / Delayed / 0.1-1.0
skin discoloration / Delayed / 0.1-1.0
hyperventilation / Early / 0-0.1
hiccups / Early / 0-0.1
parosmia / Delayed / 0-0.1
ptosis / Delayed / 0-0.1
maculopapular rash / Early / 0-0.1
leukocytosis / Delayed / 0-0.1
petechiae / Delayed / 0-0.1
nocturia / Early / 0-0.1
urinary urgency / Early / 0-0.1
headache / Early / 5.0
paresthesias / Delayed / 1.0
insomnia / Early / 5.0
anxiety / Delayed / 3.0
influenza / Delayed / 3.0
infection / Delayed / 5.0
rhinitis / Early / 5.0
pruritus / Rapid / 2.0
nasal congestion / Early / Incidence not known

DRUG INTERACTIONS

Acetaminophen: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Aspirin, ASA; Caffeine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Butalbital: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Butalbital; Caffeine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Butalbital; Caffeine; Codeine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Caffeine; Dihydrocodeine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Codeine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dextromethorphan: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dextromethorphan; Doxylamine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dextromethorphan; Phenylephrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Dichloralphenazone; Isometheptene: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Diphenhydramine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Guaifenesin; Phenylephrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Hydrocodone: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Oxycodone: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Pentazocine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Propoxyphene: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Pseudoephedrine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Acetaminophen; Tramadol: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
Aldesleukin, IL-2: (Moderate) Aldesleukin, IL-2 may affect CNS function significantly. Therefore, psychotropic pharmacodynamic interactions could occur following concomitant administration of drugs with significant CNS or psychotropic activity, such as lamotrigine. Use with caution.
Alogliptin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Alprazolam: (Moderate) Concomitant administration of alprazolam with CNS-depressant drugs, including anticonvulsants, can potentiate the CNS effects of either agent.
Amantadine: (Moderate) Coadministration of amantadine and lamotrigine may decrease amantadine clearance, resulting in increased plasma concentrations and the potential for anticholinergic adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and amantadine is excreted via this route.
Amiloride: (Moderate) Coadministration of amiloride (or amiloride; hydrochlorothiazide, HCTZ) and lamotrigine may decrease amiloride clearance, resulting in increased plasma concentrations and the potential for amiloride-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and amiloride is excreted via this route.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Coadministration of amiloride (or amiloride; hydrochlorothiazide, HCTZ) and lamotrigine may decrease amiloride clearance, resulting in increased plasma concentrations and the potential for amiloride-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and amiloride is excreted via this route.
Amoxapine: (Moderate) Amoxapine, when used concomitantly with anticonvulsants, can increase CNS depression and may also lower the seizure threshold, leading to pharmacodynamic interactions. Some anticonvulsants, such as phenobarbital or carbamazepine, may potentially induce the metabolism of amoxapine as well. Monitor patients for side effects or altered responses to drug therapy.
Amphetamines: (Major) Patients who are taking anticonvulsants for epilepsy/seizure control should use amphetamines with caution. Amphetamines may decrease the seizure threshold and increase the risk of seizures. If seizures occur, amphetamine discontinuation may be necessary.
Aripiprazole: (Minor) Coadministration of aripiprazole and lamotrigine may slightly decrease lamotrigine plasma concentrations; however, this interaction is not expected to be clinically meaningful. During clinical trials, lamotrigine exposure was reduced approximately 10% in patients (n = 18) on a stable regimen of lamotrigine 100400 mg/day who received ariprazole 1030 mg/day for 7 days, followed by 30 mg/day for an additional 7 days.
Atazanavir: (Major) Adjustments in lamotrigine maintenance dose regimens may be necessary with concomitant use of atazanavir boosted with ritonavir. No dose adjustments during dose escalation are necessary. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and atazanavir with ritonavir induces glucuronidation. Daily doses of atazanavir/ritonavir (300 mg/100 mg) in healthy volunteers reduced the AUC and Cmax of a single lamotrigine dose (100 mg) by approximately 32% and 6%, respectively. The lamotrigine half-life decreased by 27%. Concurrent use of lamotrigine and unboosted atazanavir is not expected to alter the plasma concentration of lamotrigine, and no dose adjustment of lamotrigine is necessary when administered without ritonavir.
Atazanavir; Cobicistat: (Major) Adjustments in lamotrigine maintenance dose regimens may be necessary with concomitant use of atazanavir boosted with ritonavir. No dose adjustments during dose escalation are necessary. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and atazanavir with ritonavir induces glucuronidation. Daily doses of atazanavir/ritonavir (300 mg/100 mg) in healthy volunteers reduced the AUC and Cmax of a single lamotrigine dose (100 mg) by approximately 32% and 6%, respectively. The lamotrigine half-life decreased by 27%. Concurrent use of lamotrigine and unboosted atazanavir is not expected to alter the plasma concentration of lamotrigine, and no dose adjustment of lamotrigine is necessary when administered without ritonavir.
Atropine; Hyoscyamine; Phenobarbital; Scopolamine: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant phenobarbital use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and phenobarbital induces glucuronidation. During concurrent use of lamotrigine with phenobarbital, lamotrigine steady-state concentration decreased by approximately 40%.
Azelaic Acid; Copper; Folic Acid; Nicotinamide; Pyridoxine; Zinc: (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Belladonna Alkaloids; Ergotamine; Phenobarbital: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant phenobarbital use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and phenobarbital induces glucuronidation. During concurrent use of lamotrigine with phenobarbital, lamotrigine steady-state concentration decreased by approximately 40%.
Bupropion: (Moderate) Bupropion should not be used by patients with a preexisting seizure disorder because it may lower the seizure threshold. Bupropion may also interact pharmacokinetically with anticonvulsant drugs that induce hepatic microsomal isoenzyme function such as carbamazepine, barbiturates, or phenytoin, as well as fosphenytoin and ethotoin.
Bupropion; Naltrexone: (Moderate) Bupropion should not be used by patients with a preexisting seizure disorder because it may lower the seizure threshold. Bupropion may also interact pharmacokinetically with anticonvulsant drugs that induce hepatic microsomal isoenzyme function such as carbamazepine, barbiturates, or phenytoin, as well as fosphenytoin and ethotoin.
Canagliflozin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Carbamazepine: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant carbamazepine use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and carbamazepine induces glucuronidation. During concurrent use of lamotrigine with carbamazepine, lamotrigine steady-state concentration decreased by approximately 40%. Lamotrigine may increase the concentration of the 10, 11-epoxide metabolite of carbamazepine; small studies have demonstrated mixed results when evaluating carbamazepine-epoxide concentrations in the presence of lamotrigine. Limited data suggest that there is a higher incidence of dizziness, diplopia, ataxia, and blurred vision in patients receiving lamotrigine with carbamazepine than in patients receiving lamotrigine with other AEDs; the mechanism of the interaction is not known.
Chlorpromazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Cimetidine: (Minor) Coadministration of cimetidine and lamotrigine may decrease cimetidine clearance, resulting in increased plasma concentrations and the potential for cimetidine-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and cimetidine is excreted via this route.
Clozapine: (Major) One report has described an interaction between lamotrigine and clozapine. A 3-fold increase in clozapine concentrations occurred in a patient after lamotrigine was added to the drug regimen. The patient experienced drowsiness and dizziness that were clinically significant. Measurement of clozapine plasma concentrations during the time of the interaction and after lamotrigine was discontinued indicated a probable interaction, although the mechanism of the interaction is not certain. Clozapine may interact with anticonvulsants in several ways; therefore concurrent use of clozapine in patients on antiepileptic medications is not recommended if seizures are not controlled. Clozapine lowers the seizure threshold in a dose-dependent manner and thus may induce seizures. Dosage adjustments of clozapine should be cautious.
Colesevelam: (Moderate) Colesevelam may decrease the bioavailability of lamotrigine. To minimize potential for interactions, consider administering oral anticonvulsants such as lamotrigine at least 1 hour before or at least 4 hours after colesevelam.
Dapagliflozin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant lopinavir; ritonavir use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and lopinavir; ritonavir induces glucuronidation. During concurrent use of lamotrigine with lopinavir; ritonavir in 18 healthy subjects, induction of glucuronidation by lopinavir (400 mg twice daily); ritonavir (100 mg twice daily) decreased lamotrigine AUC, Cmax, and half-life by approximately 50% to 55.4%. (Moderate) If coadministration of lamotrigine and dasabuvir; ombitasvir; paritaprevir; ritonavir is warranted, use caution and carefully monitor lamotrigine concentrations; lamotrigine dosage adjustments may be needed. Ritoanvir may increase the hepatic metabolism of lamotrigine via glucuronidation, resulting in decreased lamotrigine concentrations. Additionally, lamotrigine interactions are thought to be mediated by uridine diphosphate glucuronyltransferase (UGT), and dasabuvir, ombitasvir, and paritaprevir are UGT1A1 inhibitors. Further alterations to lamotrigine concentrations could occur.
Desmopressin: (Major) Caution is recommended if a drug that may increase the risk of water intoxication with hyponatremia, such as lamotrigine, is administered with desmopressin acetate. Two children with diabetes insipidus had decreasing desmopressin requirements with lamotrigine initiation.
Dienogest; Estradiol valerate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Dofetilide: (Major) Coadministration of lamotrigine and dofetilide is not recommended. Coadministration may decrease dofetilide clearance, resulting in increased plasma concentrations and the potential for serious adverse events, including QT prolongation and cardiac arrhythmias. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and dofetilide is excreted via this route.
Donepezil; Memantine: (Minor) Coadministration of memantine and lamotrigine may decrease memantine clearance, resulting in increased plasma concentrations and the potential for adverse events, including vertigo and mental status changes. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and memantine is excreted via this route.
Dopamine: (Moderate) Coadministration of dopamine and lamotrigine may decrease dopamine clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypertension and tachycardia. Monitor blood pressure and peripheral perfusion closely and adjust the dopamine infusion as necessary. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and dopamine is excreted via this route.
Drospirenone; Estradiol: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Drospirenone; Ethinyl Estradiol: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations. (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Empagliflozin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Ertugliflozin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Estradiol; Levonorgestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Estradiol; Norethindrone: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Estradiol; Norgestimate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Desogestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Ethynodiol Diacetate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Etonogestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations. (Moderate) Hormonal contraceptives, such as etonogestrel, may affect the metabolism of lamotrigine. Consequently, plasma concentrations of lamotrigine may decrease. Patients should be monitored for loss of efficacy of lamotrigine during concurrent use of etonogestrel.
Ethinyl Estradiol; Levonorgestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Levonorgestrel; Ferrous bisglycinate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations. (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Ethinyl Estradiol; Norelgestromin: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norethindrone Acetate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norethindrone Acetate; Ferrous fumarate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norethindrone: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norethindrone; Ferrous fumarate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norgestimate: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ethinyl Estradiol; Norgestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Etonogestrel: (Moderate) Hormonal contraceptives, such as etonogestrel, may affect the metabolism of lamotrigine. Consequently, plasma concentrations of lamotrigine may decrease. Patients should be monitored for loss of efficacy of lamotrigine during concurrent use of etonogestrel.
Famotidine: (Minor) Coadministration of famotidine and lamotrigine may decrease famotidine clearance, resulting in increased plasma concentrations and the potential for famotidine-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and famotidine is excreted via this route.
Famotidine; Ibuprofen: (Minor) Coadministration of famotidine and lamotrigine may decrease famotidine clearance, resulting in increased plasma concentrations and the potential for famotidine-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and famotidine is excreted via this route.
Fluorouracil, 5-FU: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering fluorouracil, 5-FU, which may inhibit this enzyme.
Fluphenazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Folic Acid, Vitamin B9: (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Fosphenytoin: (Moderate) When phenytoin or fosphenytoin is added to lamotrigine therapy, phenytoin decreases the steady state concentrations of lamotrigine by approximately 50 percent. If enzyme inducing antiepileptic drugs are discontinued, lamotrigine doses may need to be adjusted downward.
Glipizide; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Glyburide; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Hydroxychloroquine: (Moderate) Caution is warranted with the coadministration of hydroxychloroquine and antiepileptic drugs, such as lamotrigine. Hydroxychloroquine can lower the seizure threshold; therefore, the activity of antiepileptic drugs may be impaired with concomitant use.
Isocarboxazid: (Moderate) MAOIs can cause a variable change in seizure patterns, so careful monitoring of the patient with epilepsy is required. Also, additive CNS depression is possible if MAOIs and anticonvulsants are coadministered.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant rifampin use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and rifampin induces glucuronidation. During concurrent use of lamotrigine with rifampin in 10 volunteers, rifampin (600 mg/day for 5 days) decreased the AUC of lamotrigine (25 mg single dose) by approximately 40%.
Isoniazid, INH; Rifampin: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant rifampin use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and rifampin induces glucuronidation. During concurrent use of lamotrigine with rifampin in 10 volunteers, rifampin (600 mg/day for 5 days) decreased the AUC of lamotrigine (25 mg single dose) by approximately 40%.
Kava Kava, Piper methysticum: (Major) The German Commission E warns that any substances that act on the CNS, including anticonvulsants, may interact with kava kava. While the interactions can be pharmacodynamic in nature, kava kava has been reported to inhibit many CYP isozymes (i.e., CYP1A2, 2C9, 2C19, 2D6, 3A4, and 4A9/11) and important pharmacokinetic interactions with CNS-active agents that undergo oxidative metabolism via these CYP isozymes are also possible. Persons taking an anticonvulsant should discuss the use of herbal supplements with their health care professional prior to consuming them.
Leuprolide; Norethindrone: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Levomefolate: (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Levomefolate; Mecobalamin; Pyridoxal-5-phosphate: (Minor) L-methylfolate concentrations may be reduced when administered concomitantly with lamotrigine. Patients should be monitored closely for decreased efficacy of L-methylfolate if these agents are used together.
Levonorgestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Linagliptin; Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Lopinavir; Ritonavir: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant lopinavir; ritonavir use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and lopinavir; ritonavir induces glucuronidation. During concurrent use of lamotrigine with lopinavir; ritonavir in 18 healthy subjects, induction of glucuronidation by lopinavir (400 mg twice daily); ritonavir (100 mg twice daily) decreased lamotrigine AUC, Cmax, and half-life by approximately 50% to 55.4%.
Maprotiline: (Moderate) Maprotiline, when used concomitantly with anticonvulsants, can increase CNS depression and may also lower the seizure threshold, leading to pharmacodynamic interactions. Monitor patients on anticonvulsants carefully when maprotiline is used concurrently. Because of the lowering of seizure threshold, an alternative antidepressant may be a more optimal choice for patients taking drugs for epilepsy.
Mefloquine: (Moderate) Coadministration of mefloquine and anticonvulsants may result in lower than expected anticonvulsant concentrations and loss of seizure control. Monitoring of the anticonvulsant serum concentration is recommended. Dosage adjustments may be required during and after therapy with mefloquine.
Memantine: (Minor) Coadministration of memantine and lamotrigine may decrease memantine clearance, resulting in increased plasma concentrations and the potential for adverse events, including vertigo and mental status changes. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and memantine is excreted via this route.
Mephobarbital: (Moderate) Concurrent administration of hepatic enzyme inducing antiepileptic drugs with lamotrigine results in changes in lamotrigine half-life in both adult and pediatric patient populations. Hepatic enzyme inducing barbiturates such as phenobarbital, mephobarbital or primidone may decrease lamotrigine steady-state concentrations by about 40%. If enzyme inducing antiepileptic drugs are discontinued, lamotrigine doses may need to be adjusted downward.
Mesoridazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Mestranol; Norethindrone: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Metformin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Metformin; Pioglitazone: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Metformin; Repaglinide: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Metformin; Rosiglitazone: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Metformin; Saxagliptin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Metformin; Sitagliptin: (Moderate) Coadministration of metformin and lamotrigine may decrease metformin clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypoglycemia. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and metformin is excreted via this route.
Methotrexate: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering methotrexate, which also inhibits this enzyme.
Methsuximide: (Major) Methsuximide may reduce serum concentrations of lamotrigine by up to 70%. Conversely, if methsuximide is discontinued, lamotrigine doses may need to be adjusted downward. The mechanism by which this interaction occurs has not been established.
Molindone: (Moderate) Consistent with the pharmacology of molindone, additive effects may occur with other CNS active drugs such as anticonvulsants. In addition, seizures have been reported during the use of molindone, which is of particular significance in patients with a seizure disorder receiving anticonvulsants. Adequate dosages of anticonvulsants should be continued when molindone is added; patients should be monitored for clinical evidence of loss of seizure control or the need for dosage adjustments of either molindone or the anticonvulsant.
Monoamine oxidase inhibitors: (Moderate) MAOIs can cause a variable change in seizure patterns, so careful monitoring of the patient with epilepsy is required. Also, additive CNS depression is possible if MAOIs and anticonvulsants are coadministered.
Norethindrone: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Norgestrel: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Ombitasvir; Paritaprevir; Ritonavir: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant lopinavir; ritonavir use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and lopinavir; ritonavir induces glucuronidation. During concurrent use of lamotrigine with lopinavir; ritonavir in 18 healthy subjects, induction of glucuronidation by lopinavir (400 mg twice daily); ritonavir (100 mg twice daily) decreased lamotrigine AUC, Cmax, and half-life by approximately 50% to 55.4%. (Moderate) If coadministration of lamotrigine and dasabuvir; ombitasvir; paritaprevir; ritonavir is warranted, use caution and carefully monitor lamotrigine concentrations; lamotrigine dosage adjustments may be needed. Ritoanvir may increase the hepatic metabolism of lamotrigine via glucuronidation, resulting in decreased lamotrigine concentrations. Additionally, lamotrigine interactions are thought to be mediated by uridine diphosphate glucuronyltransferase (UGT), and dasabuvir, ombitasvir, and paritaprevir are UGT1A1 inhibitors. Further alterations to lamotrigine concentrations could occur.
Oral Contraceptives: (Major) Adult and adolescent women receiving combination oral contraceptives with lamotrigine may require close clinical monitoring and lamotrigine dosage adjustments as there is potential for decreased efficacy of both lamotrigine and the oral contraceptive. Estrogen-containing hormonal contraceptives may increase lamotrigine clearance during coadministration; in addition, side effects from lamotrigine such as dizziness, ataxia, and diplopia may occur during the placebo/off week, when lamotrigine clearance decreases. It is unknown if an interaction exists with non-oral combination contraceptives or hormone replacement therapy; however, it is possible that similar interactions could occur. Progestin-only products are not thought to change lamotrigine plasma levels. The specific dosage adjustment recommendations vary according to the type of hormonal contraception used and the presence or absence of other enzyme-inducing drug therapy. In one study, an oral contraceptive containing ethinyl estradiol; levonorgestrel 30 mcg/150 mcg administered for approximately 4.6 cycles (21 days of ethinyl estradiol (EE); levonorgestrel followed by 7 days of placebo) increased the clearance of lamotrigine 2-fold with mean decreases in AUC and Cmax of 52% and 39%, respectively. Trough lamotrigine concentrations increased an average of 2-fold by the end of the placebo week. Administration of lamotrigine 300 mg/day did not affect the kinetics of the EE component in a small group of female subjects. However, the AUC and Cmax of levonorgestrel decreased by 19% and 12%, respectively. The clinical outcome of these changes has not been studied. It is possible that EE; levonorgestrel efficacy could be reduced. Although not specifically recommended by the manufacturer, consideration should be given to prescribing progestin-only contraceptives or extended cycle combined hormonal contraceptives (e.g., Seasonale, Seasonique) to minimize lamotrigine serum concentration fluctuations). No adjustments to the initial lamotrigine dosing titration schedule are needed in women starting estrogen-containing contraceptives other than those recommended for initiation of lamotrigine in patients receiving other selected AEDs. The maintenance dose of lamotrigine following the initial titration or in those already stable on the drug will likely need to be increased 2-fold more than the usual recommended target dose to maintain consistent plasma levels in those not receiving enzyme-inducing medications (e.g., carbamazepine, phenytoin, phenobarbital, primidone, rifampin or other drugs, like rifampin, that increase lamotrigine glucuronidation, like ritonavir). Dose increases should begin when the oral contraceptive is started, and continue based upon response, not to exceed 50 to 100 mg/day per week unless lamotrigine plasma levels or response warrant otherwise. Gradual transient increases in lamotrigine plasma levels may occur during the placebo week, and may be larger if dose changes are made just prior to this phase in the hormone cycle, possibly resulting in lamotrigine toxicity. Therefore dose changes limited to the pill-free week are not recommended; if adverse effects continue to occur during the pill-free week, the overall maintenance dose may need adjustment. No dose adjustments should be needed in those stable on lamotrigine while starting or stopping estrogen-containing contraceptives and receiving enzyme-inducing medications. The lamotrigine maintenance dose will likely need to be decreased as much as 50% to maintain a consistent lamotrigine plasma level in those stopping estrogen-containing contraceptives and not receiving enzyme-inducing medications. Dosage decreases should not exceed 25% of the total daily dose per week over 2 weeks, unless lamotrigine plasma levels or response warrant otherwise. Until further data becomes available, close monitoring of lamotrigine for efficacy and toxicity is warranted in all situations.
Orlistat: (Moderate) Seizures have been reported in patients treated concomitantly with orlistat and anticonvulsants. Patients should be monitored for possible changes in the frequency and/or severity of convulsions. A mechanism for the potential interaction has not been stated.
Pemoline: (Major) A reduction in seizure threshold has been reported following concomitant administration of pemoline with anticonvulsant agents. Dosage adjustments of anticonvulsants may be necessary during simultaneous use of these drugs.
Perphenazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Perphenazine; Amitriptyline: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Phenelzine: (Moderate) MAOIs can cause a variable change in seizure patterns, so careful monitoring of the patient with epilepsy is required. Also, additive CNS depression is possible if MAOIs and anticonvulsants are coadministered.
Phenobarbital: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant phenobarbital use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and phenobarbital induces glucuronidation. During concurrent use of lamotrigine with phenobarbital, lamotrigine steady-state concentration decreased by approximately 40%.
Phenothiazines: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Phentermine; Topiramate: (Moderate) Use caution when coadministering lamotrigine and topiramate. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as lamotrigine, may increase the risk of bleeding. In pediatric patients who underwent craniotomy for epilepsy surgery (n = 84), treatment for confirmed or suspected coagulopathy was required in 5 of 7 patients taking a regimen of topiramate and lamotrigine, approximately one-third of the overall study population requiring blood products. Concurrent use may also result in significant CNS depression. Further, co-administration of topiramate and lamotrigine resulted in a 13% decrease in topiramate concentration; however, the clinical significance of this finding is unknown. Plasma concentrations of lamotrigine do not appear to be affected by the combined use of the drugs.
Phenytoin: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant phenytoin use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and phenytoin induces glucuronidation. During concurrent use of lamotrigine with phenytoin, lamotrigine steady-state concentration decreased by approximately 40%.
Pindolol: (Moderate) Coadministration of pindolol and lamotrigine may decrease pindolol clearance, resulting in increased plasma concentrations and the potential for adverse events, including hypotension. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and pindolol is excreted via this route.
Pramipexole: (Minor) Coadministration of pramipexole and lamotrigine may decrease pramipexole clearance, resulting in increased plasma concentrations and the potential for adverse events, including dizziness, mental status changes, and abnormal movements. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and pramipexole is excreted via this route.
Primidone: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant primidone use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and primidone induces glucuronidation. During concurrent use of lamotrigine with primidone, lamotrigine steady-state concentration decreased by approximately 40%.
Procainamide: (Moderate) Coadministration of lamotrigine and procainamide is not recommended. Coadministration may decrease procainamide clearance, resulting in increased plasma concentrations and the potential for serious adverse events, including QT prolongation and cardiac arrhythmias. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and procainamide is excreted via this route.
Prochlorperazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Pyrimethamine: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering pyrimethamine, which also inhibits this enzyme.
Pyrimethamine; Sulfadoxine: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering pyrimethamine, which also inhibits this enzyme.
Ranitidine: (Minor) Coadministration of ranitidine and lamotrigine may decrease ranitidine clearance, resulting in increased plasma concentrations and the potential for ranitidine-related adverse events. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and ranitidine is excreted via this route.
Rifampin: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant rifampin use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and rifampin induces glucuronidation. During concurrent use of lamotrigine with rifampin in 10 volunteers, rifampin (600 mg/day for 5 days) decreased the AUC of lamotrigine (25 mg single dose) by approximately 40%.
Ritonavir: (Major) Adjustments in lamotrigine escalation and maintenance dose regimens are necessary with concomitant lopinavir; ritonavir use. Monitoring lamotrigine plasma concentrations may be indicated, particularly during dosage adjustments. Lamotrigine is metabolized predominantly by glucuronic acid conjugation, and lopinavir; ritonavir induces glucuronidation. During concurrent use of lamotrigine with lopinavir; ritonavir in 18 healthy subjects, induction of glucuronidation by lopinavir (400 mg twice daily); ritonavir (100 mg twice daily) decreased lamotrigine AUC, Cmax, and half-life by approximately 50% to 55.4%.
Rufinamide: (Moderate) Shortening of the QT interval has occurred during treatment with rufinamide. Therefore, caution is advisable during co-administration with other drugs associated with QT-shortening including lamotrigine. In addition, a population pharmacokinetic analysis showed a 7% to 13% decrease in lamotrigine concentrations and no effect on rufinamide concentrations during concurrent use.
Selegiline: (Moderate) MAOIs can cause a variable change in seizure patterns, so careful monitoring of the patient with epilepsy is required. Also, additive CNS depression is possible if MAOIs and anticonvulsants are coadministered.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering trimethoprim, which also inhibits this enzyme.
Thiethylperazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Thioridazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Topiramate: (Moderate) Use caution when coadministering lamotrigine and topiramate. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as lamotrigine, may increase the risk of bleeding. In pediatric patients who underwent craniotomy for epilepsy surgery (n = 84), treatment for confirmed or suspected coagulopathy was required in 5 of 7 patients taking a regimen of topiramate and lamotrigine, approximately one-third of the overall study population requiring blood products. Concurrent use may also result in significant CNS depression. Further, co-administration of topiramate and lamotrigine resulted in a 13% decrease in topiramate concentration; however, the clinical significance of this finding is unknown. Plasma concentrations of lamotrigine do not appear to be affected by the combined use of the drugs.
Tranylcypromine: (Moderate) MAOIs can cause a variable change in seizure patterns, so careful monitoring of the patient with epilepsy is required. Also, additive CNS depression is possible if MAOIs and anticonvulsants are coadministered.
Trazodone: (Moderate) Trazodone can lower the seizure threshold of anticonvulsants, although the overall risk is low at therapeutic doses. Patients may require increased concentrations of anticonvulsants to achieve equivalent effects if trazodone is added.
Tricyclic antidepressants: (Moderate) Tricyclic antidepressants, when used concomitantly with anticonvulsants, can increase CNS depression and may also lower the seizure threshold.
Trifluoperazine: (Moderate) The phenothiazines, when used concomitantly with anticonvulsants, can lower the seizure threshold. Adequate dosages of anticonvulsants should be continued when a phenothiazine is added.
Trimethoprim: (Moderate) Lamotrigine inhibits dihydrofolate reductase. Caution should be exercised when administering trimethoprim, which also inhibits this enzyme.
Valproic Acid, Divalproex Sodium: (Major) Coadministration of valproic acid with lamotrigine can decrease the elimination of lamotrigine. Valproic acid more than doubles the elimination half-life of lamotrigine in both pediatric and adult patients. In a steady-state study involving 10 healthy volunteers, the elimination half-life of lamotrigine increased from 26 to 70 hours with valproate coadministration (a 165% increase). The decrease in apparent clearance of lamotrigine may occur via inhibition of lamotrigine metabolism through competition for liver glucuronidation sites. Serious skin reactions (such as Stevens-Johnson Syndrome and toxic epidermal necrolysis) have been reported with concomitant lamotrigine and valproate administration. In any patient receiving valproic acid, lamotrigine must be initiated at a reduced dosage that is less than half the dose used in patients not receiving valproic acid. In controlled clinical trials, lamotrigine had no appreciable effect on plasma valproic acid concentrations when added to existing valproic acid therapies. If valproic acid therapy is discontinued, lamotrigine doses may need to be adjusted upward. The inhibitory effects of valproic acid on lamotrigine elimination may offset the actions of other anticonvulsants with known hepatic enzyme-inducing properties on lamotrigine clearance.
Varenicline: (Minor) Coadministration of varenicline and lamotrigine may decrease varenicline clearance, resulting in increased plasma concentrations and the potential for adverse events, including nausea, vomiting, and abnormal dreams. Lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins, and varenicline is excreted via this route.

PREGNANCY AND LACTATION

According to the manufacturer, lamotrigine is distributed into human breast milk and caution is recommended if lamotrigine is continued during breast-feeding. Patients who intend to breastfeed should be informed that the drug is present in breast milk and that they should monitor their child for potential adverse effects of this drug; the health care provider should discuss the individual benefits and risks with the patient. Because there is the potential for therapeutic serum concentrations in the nursing infant, the American Academy of Pediatrics (AAP) classifies lamotrigine as a drug for which the potential effects on a nursing infant are unknown but may be of concern. Various small studies have demonstrated that lamotrigine plasma concentrations in nursing infants may be as high as 50% of maternal serum concentrations. In one study, the median milk/maternal plasma concentration ratio was 0.61 (range, 0.47—0.77) two to three weeks after delivery. The median lamotrigine plasma concentration in the neonates was approximately 30% (range, 23—50%) of the mother's plasma concentrations. Nursing neonates and young infants are at risk for high serum concentrations, as mothers who had lamotrigine dose increases during pregnancy without subsequent dose decreases following delivery may have elevated serum and milk concentrations. Immaturity of infant glucuronidation capacity necessary for lamotrigine clearance may also lead to greater drug exposure. Apnea, drowsiness, and poor sucking have been reported in nursing infants of mothers using lamotrigine; drug causality is not established. Closely monitor nursing infants for adverse events and perform infant serum concentration measurements if toxicity concerns develop. Discontinue breast-feeding in any infant that develops lamotrigine toxicity. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.

MECHANISM OF ACTION

Mechanism of Action: The exact mechanism of anticonvulsant activity is not known, but studies suggest lamotrigine may stabilize neuronal membranes by acting at voltage-sensitive sodium channels. The blocking of sodium channels can decrease the presynaptic release of glutamate and aspartate, resulting in decreased seizure frequency. This mechanism is similar to that of carbamazepine and phenytoin. Lamotrigine appears to have little or no effect on the release of GABA, dopamine, acetylcholine, or norepinephrine. Lamotrigine is also a weak dihydrofolate reductase inhibitor in vitro and in animal studies. In clinical studies, however, no effect of lamotrigine on folate concentrations has been noted, although it is possible that folate concentrations may decrease during gestation.

PHARMACOKINETICS

Lamotrigine is administered orally as conventional tablets, chewable tablets, orally disintegrating tablets (ODT), and extended-release tablets. The volume of distribution is independent of dose and duration of therapy. Distribution into the CNS is not known. Extensive placental transfer appears to occur. In 9 women, the maternal plasma concentrations immediately after delivery were similar to concentrations found in the umbilical cords. Further, lamotrigine is distributed into breast milk. Two to three weeks after delivery, the median milk:maternal plasma concentration ratio was 0.61 (range, 0.47—0.77); the median plasma concentration in the neonates was approximately 30% (range, 23—50%) of the mother's plasma concentrations. Protein binding is 55% at plasma concentrations up to 10 mcg/ml.
 
Lamotrigine has a negligible first pass effect, and undergoes glucuronidation in the liver. Carbamazepine, phenytoin, phenobarbital, and primidone can decrease lamotrigine half-life, presumably through induction of the hepatic enzyme uridine diphosphate glucuronyltransferase (UGT). Valproic acid decreases lamotrigine clearance and more than doubles elimination half-life, whether given with or without the other antiepileptic drugs. After multiple dosing in normal adult volunteers receiving no other medications, lamotrigine may induce its own metabolism which may decrease the half-life by 25% and increase plasma clearance by 37%. The mean plasma half-life in adults is approximately 24 hours (range 14—59 hours). Overall, 70% of a dose is excreted by the kidneys, 75—90% as metabolites. Less than 10% of a dose is eliminated unchanged by the kidney.
 
Affected cytochrome P450 isoenzymes and drug transporters: UGT and OCT2
Lamotrigine is predominately metabolized by glucuronic acid conjugation; hence, drugs that are known to inhibit or induce glucuronidation may alter its' clearance. Carbamazepine, phenytoin, phenobarbital, and primidone can decrease lamotrigine half-life, presumably through induction of the hepatic enzyme uridine diphosphate glucuronyltransferase (UGT). In addition, lamotrigine is an inhibitor of renal tubular secretion via organic cationic transporter 2 (OCT2) proteins at potentially clinically relevant concentrations, and may increase plasma concentrations of agents substantially excreted by this route.