Qudexy XR

Anticonvulsants, Miscellaneous
Other Anti-migraine Agents

For storage information, see specific product information within the How Supplied section.
Hazardous Drugs Classification
NIOSH 2016 List: Group 3
NIOSH (Draft) 2020 List: Table 2
Observe and exercise appropriate precautions for handling, preparation, administration, and disposal of hazardous drugs.
Use gloves to handle. Cutting, crushing, or otherwise manipulating tablets/capsules will increase exposure and require additional protective equipment. Eye/face and respiratory protection may be needed during preparation and administration.

visual impairment / Early / 1.0-3.0
hearing loss / Delayed / 1.0-2.0
seizures / Delayed / 1.0-1.0
thrombosis / Delayed / 0.1-1.0
pulmonary embolism / Delayed / 0.1-1.0
oliguria / Early / 0.1-1.0
bradycardia / Rapid / 0-1.0
AV block / Early / 0.1-1.0
pancytopenia / Delayed / 0-0.1
acute cerebellar syndrome / Early / 1.0
bronchospasm / Rapid / 1.0
suicidal ideation / Delayed / Incidence not known
ocular hypertension / Delayed / Incidence not known
erythema multiforme / Delayed / Incidence not known
toxic epidermal necrolysis / Delayed / Incidence not known
Stevens-Johnson syndrome / Delayed / Incidence not known
pemphigus / Delayed / Incidence not known
pancreatitis / Delayed / Incidence not known

hyperammonemia / Delayed / 0-26.0
memory impairment / Delayed / 0-11.0
nystagmus / Delayed / 10.0-10.0
depression / Delayed / 0-9.0
hyperthyroidism / Delayed / 0-8.0
hypophosphatemia / Delayed / 0-6.0
bleeding / Early / 0.2-4.5
involuntary movements / Delayed / 0-4.0
ataxia / Delayed / 3.0-4.0
confusion / Early / 0-4.0
blurred vision / Early / 2.0-4.0
urinary incontinence / Early / 1.0-4.0
gastritis / Delayed / 0-3.0
anemia / Delayed / 1.0-3.0
dyspnea / Early / 1.0-3.0
cystitis / Delayed / 1.0-3.0
nephrolithiasis / Delayed / 0-3.0
vaginal bleeding / Delayed / 0-3.0
ejaculation dysfunction / Delayed / 0-3.0
hypertonia / Delayed / 0-3.0
aphasia / Delayed / 2.0-2.0
dysarthria / Delayed / 0-2.0
leukopenia / Delayed / 1.0-2.0
secondary malignancy / Delayed / 0-2.0
hematuria / Delayed / 0-2.0
hot flashes / Early / 1.0-2.0
edema / Delayed / 1.0-2.0
hypertension / Early / 0-2.0
dysphonia / Delayed / 0.1-1.0
hyperesthesia / Delayed / 0.1-1.0
EEG changes / Delayed / 0.1-1.0
peripheral neuropathy / Delayed / 0.1-1.0
scotomata / Delayed / 0.1-1.0
delirium / Early / 0.1-1.0
euphoria / Early / 0.1-1.0
esophagitis / Delayed / 0.1-1.0
dysphagia / Delayed / 0-1.0
melena / Delayed / 0.1-1.0
glossitis / Early / 0-1.0
stomatitis / Delayed / 0.1-1.0
fecal incontinence / Early / 0-1.0
gingival hyperplasia / Delayed / 0-1.0
hemorrhoids / Delayed / 0.1-1.0
thrombocytosis / Delayed / 0.1-1.0
eosinophilia / Delayed / 0.1-1.0
thrombocytopenia / Delayed / 0-1.0
hematoma / Early / 0-1.0
lymphadenopathy / Delayed / 0.1-1.0
lymphopenia / Delayed / 0.1-1.0
photophobia / Early / 0.1-1.0
urinary retention / Early / 0.1-1.0
orthostatic hypotension / Delayed / 0.1-1.0
peripheral vasodilation / Rapid / 0.1-1.0
hypotension / Rapid / 0.1-1.0
angina / Early / 0.1-1.0
dyskinesia / Delayed / 0.1-1.0
dystonic reaction / Delayed / 0.1-1.0
hypocalcemia / Delayed / 0.1-1.0
dehydration / Delayed / 0.1-1.0
hypoglycemia / Early / 1.0-1.0
hyperglycemia / Delayed / 0.1-1.0
hyperlipidemia / Delayed / 0.1-1.0
diabetes mellitus / Delayed / 0.1-1.0
phlebitis / Rapid / 0.1-1.0
mania / Early / 0-0.1
lymphocytosis / Delayed / 0-0.1
polycythemia / Delayed / 0-0.1
iritis / Delayed / 0-0.1
hyponatremia / Delayed / 0-0.1
hypernatremia / Delayed / 0-0.1
migraine / Early / 1.0
psychosis / Early / 1.0
hallucinations / Early / 1.0
constipation / Delayed / 1.0
conjunctivitis / Delayed / 1.0
candidiasis / Delayed / 1.0
impotence (erectile dysfunction) / Delayed / 1.0
chest pain (unspecified) / Early / 1.0
encephalopathy / Delayed / Incidence not known
hyperemia / Delayed / Incidence not known
myopia / Delayed / Incidence not known
bullous rash / Early / Incidence not known
hyperthermia / Delayed / Incidence not known

paresthesias / Delayed / 2.0-51.0
fatigue / Early / 7.0-19.0
weight loss / Delayed / 6.0-17.0
drowsiness / Early / 2.0-15.0
dysgeusia / Early / 2.0-15.0
abdominal pain / Early / 6.0-15.0
anorexia / Delayed / 4.0-15.0
infection / Delayed / 1.0-15.0
dizziness / Early / 0-14.0
nausea / Early / 0-14.0
fever / Early / 1.0-12.0
diplopia / Early / 10.0-10.0
sinusitis / Delayed / 1.0-10.0
insomnia / Early / 0-9.0
diarrhea / Early / 2.0-9.0
hypoesthesia / Delayed / 4.0-8.0
anxiety / Delayed / 0-8.0
psychomotor impairment / Early / 0-8.0
emotional lability / Early / 0-8.0
purpura / Delayed / 0-8.0
epistaxis / Delayed / 0-8.0
laryngitis / Delayed / 0-8.0
cough / Delayed / 2.0-7.0
hypersalivation / Early / 0-6.0
pharyngitis / Delayed / 2.0-6.0
asthenia / Delayed / 0-6.0
hyperkinesis / Delayed / 5.0-5.0
dyspepsia / Early / 3.0-5.0
xerostomia / Early / 1.0-5.0
rhinitis / Early / 1.0-5.0
flushing / Rapid / 0-5.0
rash / Early / 1.0-4.0
alopecia / Delayed / 1.0-4.0
pruritus / Rapid / 1.0-4.0
vertigo / Early / 0-3.0
libido decrease / Delayed / 0-3.0
vomiting / Early / 0-3.0
increased urinary frequency / Early / 0-3.0
acne vulgaris / Delayed / 2.0-3.0
hyporeflexia / Delayed / 0-2.0
irritability / Delayed / 2.0-2.0
agitation / Early / 1.0-2.0
hypertrichosis / Delayed / 2.0-2.0
menorrhagia / Delayed / 1.0-2.0
amenorrhea / Delayed / 2.0-2.0
leukorrhea / Delayed / 2.0-2.0
polydipsia / Early / 1.0-2.0
tinnitus / Delayed / 0-2.0
ptosis / Delayed / 0.1-1.0
paranoia / Early / 0.1-1.0
appetite stimulation / Delayed / 0-1.0
weight gain / Delayed / 0-1.0
flatulence / Early / 0-1.0
gingivitis / Delayed / 0-1.0
xerophthalmia / Early / 0.1-1.0
lacrimation / Early / 1.0-1.0
pallor / Early / 0-1.0
polyuria / Early / 0.1-1.0
nocturia / Early / 0-1.0
seborrhea / Delayed / 1.0-1.0
skin discoloration / Delayed / 1.0-1.0
hyperhidrosis / Delayed / 0-1.0
drug-induced body odor / Delayed / 0-1.0
breast discharge / Delayed / 0.1-1.0
parosmia / Delayed / 0.1-1.0
libido increase / Delayed / 0-0.1
mydriasis / Early / 0-0.1
tremor / Early / 1.0
headache / Early / 1.0
gastroesophageal reflux / Delayed / 1.0
ocular pain / Early / 1.0
menstrual irregularity / Delayed / 1.0
syncope / Early / 1.0
hypothermia / Delayed / Incidence not known
ecchymosis / Delayed / Incidence not known
oligohidrosis / Delayed / Incidence not known

EPRONTIA, Qudexy XR, Topamax, Topamax Sprinkle, Topiragen, Trokendi XR

Rx

Oral anticonvulsant; weak carbonic anhydrase inhibitor
Used for partial and generalized seizures, Lennox-Gastaut, refractory seizures, and migraine prophylaxis; off-label uses include binge-eating disorder and alcohol or cocaine use disorder
Close monitoring for emerging or worsening suicidal thoughts/behavior or depression recommended

†Indicates off-label use

Specific guidelines for dosage adjustments in hepatic impairment are not available; however, clearance may be reduced.

Patients with renal impairment may require a longer time than patients with normal renal function to reach steady-state with each topiramate dosage adjustment.
CrCl 70 mL/minute or more: No dosage adjustment needed.
CrCl less than 70 mL/minute: In adults, reduce the topiramate dose to one-half of the usual dose.
In pediatric patients, adjustment to the usual mg/kg dosage may be required, but should be individualized since clearance rates are higher in the pediatric population than in adults. Some experts recommend administering one-half of the usual dose for pediatric patients with a GFR 10 to 50 mL/minute/1.73 m2 and one-quarter of the usual dose for pediatric patients with a GFR less than 10 mL/minute/1.73 m2.
 
Intermittent hemodialysis
During the hemodialysis session, adult patients clear topiramate at a rate that is 4 to 6 times greater than an adult person with normal renal function. A supplemental dose of topiramate may be required during or post-hemodialysis in some patients. Dosage adjustments should be based on duration of dialysis period, clearance rate of the dialysis system being used, and the effective renal clearance of topiramate in the patient to be dialyzed.

Abacavir; Dolutegravir; Lamivudine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Concomitant use of dihydrocodeine with topiramate can decrease dihydrocodeine levels, resulting in less metabolism by CYP2D6 and decreased dihydromorphine concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. If coadministration is necessary, monitor for reduced efficacy of dihydrocodeine and signs of opioid withdrawal; consider increasing the dose of dihydrocodeine as needed. If topiramate is discontinued, consider a dose reduction of dihydrocodeine and frequently monitor for signs or respiratory depression and sedation. Topiramate is a weak inducer of CYP3A4, an isoenzyme partially responsible for the metabolism of dihydrocodeine.
Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Acetaminophen; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetaminophen; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Acetazolamide: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Alogliptin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Alogliptin; Pioglitazone: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Alprazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Amitriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression.
Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Atorvastatin: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Benazepril: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Celecoxib: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Olmesartan: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Valsartan: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide. (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Amobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Amphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Amphetamine; Dextroamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Amphetamines: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Anticholinergics: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Anxiolytics; Sedatives; and Hypnotics: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Apixaban: (Moderate) Concurrent use of topiramate and anticoagulants, such as apixaban, may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (2-3%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation.
Aprepitant, Fosaprepitant: (Moderate) Use caution if topiramate and aprepitant, fosaprepitant are used concurrently and monitor for a possible decrease in the efficacy of aprepitant for several days after administration of a multi-day aprepitant regimen. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer; aprepitant is a CYP3A4 substrate. When a single dose of aprepitant (375 mg, or 3 times the maximum recommended dose) was administered on day 9 of a 14-day rifampin regimen (a strong CYP3A4 inducer), the AUC of aprepitant decreased approximately 11-fold and the mean terminal half-life decreased by 3-fold. The manufacturer of aprepitant recommends avoidance of administration with strong CYP3A4 inducers, but does not provide guidance for weak-to-moderate inducers. After administration, fosaprepitant is rapidly converted to aprepitant and shares the same drug interactions.
Aripiprazole: (Moderate) Monitor for unusal drowsiness and excessive sedation during concomitant aripiprazole and topiramate use due to the risk for additive CNS depression.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Aspirin, ASA; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Atazanavir: (Moderate) Caution is warranted when atazanavir is administered with topiramate as there is a potential for decreased concentrations of atazanavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Atazanavir is a substrate of CYP3A4.
Atazanavir; Cobicistat: (Moderate) Caution is warranted when atazanavir is administered with topiramate as there is a potential for decreased concentrations of atazanavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Atazanavir is a substrate of CYP3A4. (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
Atogepant: (Major) Avoid use of atogepant and topiramate when atogepant is used for chronic migraine. Use an atogepant dose of 30 or 60 mg PO once daily for episodic migraine if coadministered with topiramate. Concurrent use may decrease atogepant exposure and reduce efficacy. Atogepant is a CYP3A substrate and topiramate is a weak CYP3A inducer. Coadministration resulted in a 25% reduction in atogepant overall exposure and a 24% reduction in atogepant peak concentration.
Atovaquone; Proguanil: (Minor) Proguanil is metabolized to cycloguanil by CYP2C19. Potential interactions between proguanil or cycloguanil and other drugs that are CYP2C19 inhibitors are unknown. Use caution when combining atovaquone; proguanil with CYP2C19 inhibitors, such as topiramate.
Atropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Atropine; Difenoxin: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Barbiturates: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Belladonna; Opium: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Belzutifan: (Moderate) Monitor for anemia and hypoxia if concomitant use of topiramate with belzutifan is necessary due to increased plasma exposure of belzutifan which may increase the incidence and severity of adverse reactions. Reduce the dose of belzutifan as recommended if anemia or hypoxia occur. Belzutifan is a CYP2C19 substrate and topiramate is a CYP2C19 inhibitor.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Benzodiazepines: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Benzphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Benztropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Brexpiprazole: (Moderate) Because brexpiprazole is partially metabolized by CYP3A4, concurrent use of CYP3A4 inducers such as topiramate may result in decreased plasma concentrations of brexpiprazole. If these agents are used in combination, the patient should be carefully monitored for a decrease in brexpiprazole efficacy. An increase in brexpiprazole dosage may be clinically warranted in some patients. Similar precautions apply to combination products containing topiramate such as phentermine; topiramate.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Bumetanide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Bupivacaine; Lidocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Butalbital; Acetaminophen: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Acetaminophen; Caffeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Cabotegravir; Rilpivirine: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Canagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Carbamazepine: (Moderate) A topiramate dosage adjustment may be needed during concomitant carbamazepine use. Concomitant administration of topiramate with carbamazepine resulted in a clinically significant decrease (40%) in plasma topiramate concentrations.
Carbonic anhydrase inhibitors: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Cariprazine: (Major) Cariprazine and its active metabolites are extensively metabolized by CYP3A4. Concurrent use of cariprazine with CYP3A4 inducers, such as topiramate, has not been evaluated and is not recommended because the net effect on active drug and metabolites is unclear.
Celecoxib; Tramadol: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Chlordiazepoxide: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlordiazepoxide; Amitriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression. (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlordiazepoxide; Clidinium: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia. (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Chlorothiazide: (Moderate) Topiramate is a carbonic anhydrase inhibitor. Concurrent use of topiramate with non-potassium sparing diuretics (e.g., thiazide diuretics) may potentiate the potassium-wasting action of these diuretics. Monitor baseline and periodic potassium concentrations during coadministration.
Chlorpheniramine; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Chlorpromazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Cilostazol: (Moderate) Concurrent use of topiramate and drugs that affect platelet function such as cilostazol may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (2-3%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation. In addition, cilostazol is metabolized by the cytochrome P450 CYP2C19 hepatic isoenzyme and may interact with medications that are inhibitors of CYP2C19, including topiramate.
Citalopram: (Moderate) Limit the dose of citalopram to 20 mg/day if coadministered with topiramate. Concurrent use may increase citalopram exposure increasing the risk of QT prolongation. Citalopram is a sensitive CYP2C19 substrate; topiramate is a weak inhibitor of CYP2C19.
Clomipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant clomipramine and topiramate use due to the risk for additive CNS depression.
Clonazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Clorazepate: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4.
Cobimetinib: (Moderate) If concurrent use of cobimetinib and topiramate is necessary, use caution and monitor for decreased efficacy of cobimetinib. Cobimetinib is a CYP3A substrate in vitro, and topiramate is a weak inducer of CYP3A. The manufacturer of cobimetinib recommends avoiding coadministration of cobimetinib with moderate or strong CYP3A inducers based on simulations demonstrating that cobimetinib exposure would decrease by 73% or 83% when coadministered with a moderate or strong CYP3A inducer, respectively. Guidance is not available regarding concomitant use of cobimetinib with weak CYP3A inducers.
Codeine; Phenylephrine; Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Codeine; Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Conjugated Estrogens: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Conjugated Estrogens; Bazedoxifene: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Conjugated Estrogens; Medroxyprogesterone: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Dapagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Dapsone: (Minor) The metabolism of dapsone may be accelerated when administered concurrently with topiramate, a known inducer of CYP3A4. Coadministration is expected to decrease the plasma concentration of dapsone and increase the formation of dapsone hydroxylamine (a metabolite associated with hemolysis). If these drugs must be administered together, closely monitor for a reduction in dapsone efficacy and signs of hemolytic anemia.
Darunavir: (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Darunavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when darunavir is administered with topiramate as there is a potential for decreased concentrations of darunavir. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Darunavir is a substrate of CYP3A4.
Delavirdine: (Moderate) Delavirdine is a potent inhibitor of cytochrome P450 2C9 and might decrease topiramate metabolism leading to increased topiramate serum concentrations and a risk of adverse reactions.
Desipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant desipramine and topiramate use due to the risk for additive CNS depression.
Desogestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Dextroamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Dichlorphenamide: (Moderate) Use dichlorphenamide and topiramate, another carbonic anhydrase inhibitor, together with caution as both drugs can cause metabolic acidosis. Concurrent use may increase the severity of metabolic acidosis. Measure sodium bicarbonate concentrations at baseline and periodically during dichlorphenamide treatment. If metabolic acidosis occurs or persists, consider reducing the dose or discontinuing dichlorphenamide therapy.
Dicyclomine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Dienogest; Estradiol valerate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Digoxin: (Moderate) Serum digoxin AUC was decreased by 12% when coadministered with topiramate. Although the clinical relevance has not been determined, the clinician should be aware that serum digoxin concentrations may be affected when digoxin and topiramate are used concomitantly.
Diltiazem: (Moderate) Monitor for loss of diltiazem efficacy and an increase in topiramate-related adverse events during coadministration. Concomitant use of diltiazem (240 mg) with topiramate (150 mg/day) resulted in a 10% decrease in Cmax and a 25% decrease in diltiazem AUC, a 27% decrease in Cmax and an 18% decrease in desacetyl diltiazem AUC, and no effect on N-desmethyl diltiazem. Co-administration of topiramate with diltiazem resulted in a 16% increase in Cmax and a 19% increase in AUC of topiramate.
Diphenhydramine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Ibuprofen: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Naproxen: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenhydramine; Phenylephrine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with diphenhydramine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Diphenoxylate; Atropine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Dolutegravir: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Dolutegravir; Lamivudine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme.
Dolutegravir; Rilpivirine: (Moderate) Caution is warranted when dolutegravir is administered with topiramate as there is a potential for decreased dolutegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Dolutegravir is partially metabolized by this isoenzyme. (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Doravirine: (Minor) Concurrent administration of doravirine and topiramate may result in decreased doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Doravirine; Lamivudine; Tenofovir disoproxil fumarate: (Minor) Concurrent administration of doravirine and topiramate may result in decreased doravirine exposure, resulting in potential loss of virologic control. Doravirine is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Doxepin: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant doxepin and topiramate use due to the risk for additive CNS depression.
Doxorubicin Liposomal: (Major) Topiramate is a mild CYP3A4 inducer; doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of topiramate and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Doxorubicin: (Major) Topiramate is a mild CYP3A4 inducer; doxorubicin is a major substrate of CYP3A4. Inducers of CYP3A4 may decrease the concentration of doxorubicin and compromise the efficacy of chemotherapy. Avoid coadministration of topiramate and doxorubicin if possible. If not possible, monitor doxorubicin closely for efficacy.
Doxylamine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Doxylamine; Pyridoxine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with doxylamine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Dronabinol: (Moderate) Use caution if coadministration of dronabinol with topiramate is necessary, and monitor for a decrease in the efficacy of dronabinol. Dronabinol is a CYP2C9 and 3A4 substrate; topiramate is a weak inducer of CYP3A4. Concomitant use may result in decreased plasma concentrations of dronabinol.
Dronedarone: (Major) The concomitant use of dronedarone and CYP3A4 inducers should be avoided. Dronedarone is metabolized by CYP3A. Topiramate induces CYP3A4. Coadministration of CYP3A4 inducers, such as topiramate, with dronedarone may result in reduced plasma concentration and subsequent reduced effectiveness of dronedarone therapy.
Droperidol: (Major) Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Drospirenone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Estetrol: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Elagolix; Estradiol; Norethindrone acetate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Elbasvir; Grazoprevir: (Moderate) Caution is advised when administering elbasvir with topiramate. Topiramate is a mild CYP3A inducer, while elbasvir is a substrate of CYP3A. Use of these drugs together may decrease the plasma concentrations of elbasvir and could result in decreased virologic response. (Moderate) Caution is advised when administering elbasvir; grazoprevir with topiramate. Topiramate is a mild CYP3A inducer, while grazoprevir is a substrate of CYP3A. Use of these drugs together may decrease the plasma concentrations of grazoprevir and could result in decreased virologic response.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Caution is warranted when cobicistat is administered with topiramate as there is a potential for decreased concentrations of cobicistat. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Cobicistat is a substrate of CYP3A4. (Moderate) Caution is warranted when elvitegravir is administered with topiramate as there is a potential for decreased elvitegravir concentrations. Decreased antiretroviral concentrations may lead to a reduction of antiretroviral efficacy and the potential development of viral resistance. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Elvitegravir is a CYP3A4 substrate.
Empagliflozin; Linagliptin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended.
Empagliflozin; Linagliptin; Metformin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Empagliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Emtricitabine; Rilpivirine; Tenofovir Disoproxil Fumarate: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Ertugliflozin; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Estazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Esterified Estrogens: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Esterified Estrogens; Methyltestosterone: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Estradiol; Levonorgestrel: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Norethindrone: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Norgestimate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estradiol; Progesterone: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Estrogens affected by CYP3A inducers: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Estropipate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination.
Eszopiclone: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Ethacrynic Acid: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking topiramate. Topiramate is a CNS depressant. Concomitant administration of topiramate with alcohol can result in significant CNS depression. Trokendi XR is contraindicated with recent alcohol use (i.e., within 6 hours before and 6 hours after use). In the presence of alcohol, the pattern of topiramate release from Trokendi XR is significantly altered. As a result, plasma concentrations of topiramate may be markedly higher soon after dosing and subtherapeutic later in the day. (Major) Avoid alcohol with topiramate. Topiramate is a CNS depressant. Concomitant administration of topiramate with alcohol can result in significant CNS depression. Trokendi XR is contraindicated with recent alcohol use (i.e., within 6 hours before and 6 hours after use). In the presence of alcohol, the pattern of topiramate release from Trokendi XR is significantly altered. As a result, plasma concentrations of topiramate may be markedly higher soon after dosing and subtherapeutic later in the day.
Ethinyl Estradiol; Norelgestromin: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethinyl Estradiol; Norethindrone Acetate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethinyl Estradiol; Norgestrel: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Ethotoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Ethynodiol Diacetate; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Etonogestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Etonogestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Fentanyl: (Moderate) Consider an increased dose of fentanyl and monitor for evidence of opioid withdrawal if concurrent use of topiramate is necessary. If topiramate is discontinued, consider reducing the fentanyl dosage and monitor for evidence of respiratory depression. Coadministration of a CYP3A4 inducer like topiramate with fentanyl, a CYP3A4 substrate, may decrease exposure to fentanyl resulting in decreased efficacy or onset of withdrawal symptoms in a patient who has developed physical dependence to fentanyl. Fentanyl plasma concentrations will increase once the inducer is stopped, which may increase or prolong the therapeutic and adverse effects, including serious respiratory depression.
Flavoxate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Flibanserin: (Major) The concomitant use of flibanserin with CYP3A4 inducers significantly decreases flibanserin exposure compared to the use of flibanserin alone. Therefore, concurrent use of flibanserin and CYP3A4 inducers, such as topiramate is not recommended.
Fluphenazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Flurazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Fosphenytoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Furosemide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Gefitinib: (Moderate) Monitor for clinical response of gefitinib if used concomitantly with topiramate. Gefitinib is metabolized significantly by CYP3A4 and topiramate is a weak CYP3A4 inducer; coadministration may increase gefitinib metabolism and decrease gefitinib concentrations. This also applies to combination products containing topiramate, such as phentermine; topiramate. While the manufacturer has provided no guidance regarding the use of gefitinib with mild or moderate CYP3A4 inducers, administration of a single 500 mg gefitinib dose with a concurrent strong CYP3A4 inducer (rifampin) resulted in reduced mean AUC of gefitinib by 83%.
Glipizide; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Glyburide: (Minor) Coadministration of glyburide with topiramate may decrease systemic exposure to glyburide. A pharmacokinetic drug interaction study evaluated the combination of topiramate and glyburide. Reductions in AUC and Cmax were noted for glyburide and the active metabolites.
Glyburide; Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known. (Minor) Coadministration of glyburide with topiramate may decrease systemic exposure to glyburide. A pharmacokinetic drug interaction study evaluated the combination of topiramate and glyburide. Reductions in AUC and Cmax were noted for glyburide and the active metabolites.
Glycopyrrolate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Glycopyrrolate; Formoterol: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Guaifenesin; Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Homatropine; Hydrocodone: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia. (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydantoins: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Hydrocodone: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydrocodone; Ibuprofen: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydrocodone; Pseudoephedrine: (Moderate) Monitor for reduced efficacy of hydrocodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of hydrocodone as needed. If topiramate is discontinued, consider a dose reduction of hydrocodone and frequently monitor for signs or respiratory depression and sedation. Hydrocodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease hydrocodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Hydroxychloroquine: (Moderate) Monitor persons with epilepsy for seizure activity during concomitant topiramate and hydroxychloroquine use. Hydroxychloroquine can lower the seizure threshold; therefore, the activity of antiepileptic drugs may be impaired with concomitant use.
Hydroxyzine: (Moderate) Monitor for increased CNS effects if topiramate is coadministered with hydroxyzine. Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression, such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Hyoscyamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Ibuprofen; Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Imatinib: (Moderate) Imatinib is a potent inhibitors of cytochrome P450 2C9 and might decrease topiramate metabolism leading to increased topiramate serum concentrations and a risk of adverse reactions.
Imipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant imipramine and topiramate use due to the risk for additive CNS depression.
Indacaterol; Glycopyrrolate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Isavuconazonium: (Moderate) Caution and close monitoring are warranted when isavuconazonium is administered with topiramate as there is a potential for decreased concentrations of isavuconazonium. Decreased isavuconazonium concentrations may lead to a reduction of antifungal efficacy and the potential for treatment failure. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Isavuconazole, the active moiety of isavuconazonium, is a sensitive substrate of this enzyme.
Lacosamide: (Moderate) Use lacosamide with caution in patients taking concomitant medications that affect cardiac conduction including those that prolong PR interval, such as sodium channel blocking anticonvulsants (e.g., topiramate), because of the risk of AV block, bradycardia, or ventricular tachyarrhythmia. If use together is necessary, obtain an ECG prior to lacosamide initiation and after treatment has been titrated to steady-state. In addition, monitor patients receiving lacosamide via the intravenous route closely.
Lamotrigine: (Moderate) Monitor for loss of topiramate efficacy and/or an increase in topiramate-related adverse events during coadministration. Coadministration has resulted in both a 13% decrease and 15% increase in topiramate concentrations.
Leuprolide; Norethindrone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levamlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Levonorgestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Lidocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Lidocaine; Epinephrine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Lidocaine; Prilocaine: (Moderate) Concomitant use of systemic lidocaine and topiramate may decrease lidocaine plasma concentrations. Higher lidocaine doses may be required; titrate to effect. Lidocaine is a CYP3A4 and CYP1A2 substrate; topiramate induces CYP3A4.
Linagliptin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended.
Linagliptin; Metformin: (Major) Inducers of CYP3A4 (e.g., topiramate) can decrease exposure to linagliptin to subtherapeutic and likely ineffective concentrations. For patients requiring use of such drugs, an alternative to linagliptin is strongly recommended. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Lisdexamfetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Lithium: (Moderate) Monitor serum lithium concentrations during concomitant high-dose topiramate use. Lithium concentrations were unaffected during treatment with topiramate 200 mg/day; however, there was an observed increase in systemic exposure of lithium (26%) after topiramate doses up to 600 mg/day.
Loop diuretics: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Lopinavir; Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Lorazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Lumateperone: (Major) Avoid coadministration of lumateperone and topiramate as concurrent use may decrease lumateperone exposure which may reduce efficacy. Lumateperone is a CYP3A4 substrate; topiramate is a weak CYP3A4 inducer.
Lurasidone: (Moderate) Because lurasidone is primarily metabolized by CYP3A4, decreased plasma concentrations of lurasidone may theoretically occur when the drug is co-administered with inducers of CYP3A4 such as topiramate.
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.
Maraviroc: (Minor) Use caution if coadministration of maraviroc with topiramate is necessary, due to a possible decrease in maraviroc exposure. Maraviroc is a CYP3A substrate and topiramate is a CYP3A4 inducer. Monitor for a decrease in maraviroc efficacy with concomitant use.
Medroxyprogesterone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Mefloquine: (Moderate) Topiramate induces CYP3A4 and may increase the metabolism of mefloquine if coadministered. Use may reduce the clinical efficacy of mefloquine, increasing the risk of Plasmodium falciparum resistance during treatment of malaria. Coadministration of mefloquine and anticonvulsants may also result in lower than expected anticonvulsant concentrations and loss of seizure control. Monitoring of drug concentrations (if therapeutic monitoring is advised for the anticonvulsant) is recommended. When topiramate is used for other conditions, monitor for clinical efficacy. Mefloquine may additionally cause CNS side effects that may cause seizures or alter moods or behaviors.
Meprobamate: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Metformin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Repaglinide: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Saxagliptin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Metformin; Sitagliptin: (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Methamphetamine: (Moderate) Monitor for amphetamine-related adverse events if coadministered with topiramate. Concurrent use may increase amphetamine concentrations, resulting in potentiation of the action of amphetamines.
Methazolamide: (Major) Avoid concurrent use of acetazolamide or methazolamide with topiramate. Topiramate is a weak carbonic anhydrase inhibitor. Concomitant use of topiramate with acetazolamide or methazolamide may create a physiological environment that increases the risk of renal stone formation associated with topiramate use. Additionally, through an additive effect, the use of topiramate with agents that may increase the risk for heat-related disorders (acetazolamide and methazolamide), may lead to oligohidrosis, hyperthermia and heat stroke.
Methenamine: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Methenamine; Sodium Salicylate: (Moderate) Carbonic anhydrase inhibiting drugs, such as topiramate (a weak carbonic anhydrase inhibitor) can alkalinize the urine, thereby decreasing the effectiveness of methenamine by inhibiting the conversion of methenamine to formaldehyde.
Methohexital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Methscopolamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Midazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
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.
Nanoparticle Albumin-Bound Sirolimus: (Moderate) Monitor for reduced sirolimus efficacy if sirolimus is coadministered with topiramate. Concomitant use may decrease sirolimus exposure. Sirolimus is a CYP3A substrate and topiramate is a weak CYP3A inducer.
Neostigmine; Glycopyrrolate: (Moderate) Mo nitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Nirmatrelvir; Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Nisoldipine: (Major) Avoid coadministration of nisoldipine with topiramate due to decreased plasma concentrations of nisoldipine. Alternative antihypertensive therapy should be considered. Nisoldipine is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Coadministration with a strong CYP3A4 inducer lowered nisoldipine plasma concentrations to undetectable levels.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norgestimate; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Norgestrel: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Nortriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant nortriptyline and topiramate use due to the risk for additive CNS depression.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide. (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Oxazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Oxybutynin: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Oxycodone: (Moderate) Monitor for reduced efficacy of oxycodone and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of oxycodone as needed. If topiramate is discontinued, consider a dose reduction of oxycodone and frequently monitor for signs of respiratory depression and sedation. Oxycodone is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease oxycodone levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Pazopanib: (Moderate) Coadministration of pazopanib and topiramate may cause a decrease in systemic concentrations of pazopanib. Use caution when administering these drugs concomitantly. Pazopanib is a substrate for CYP3A4. Topiramate in a weak CYP3A4 inducer.
Pentobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Perampanel: (Moderate) During clinical trials, co-administration of topiramate and perampanel to patients led to a 20% decrease in the AUC of perampanel compared to patients not taking enzyme-inducing antiepileptic drugs. Topiramate is an inducer of CYP3A4, while perampanel is a substrate of this enzyme. Patients taking topiramate who begin treatment with perampanel should be closely monitored for adverse effects and receive a higher initial dose of perampanel. Addition or withdrawal of enzyme-inducing antiepileptic drugs may require a perampanel dose adjustment.
Perindopril; Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Perphenazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Perphenazine; Amitriptyline: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression. (Moderate) Monitor for unusual drowsiness or excess sedation and for increased amitriptyline-related adverse events during concomitant topiramate use. Concomitant use resulted in an increase in amitriptyline exposure by 12% and may increase the risk for additive CNS depression.
Phenobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately. (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Phenothiazines: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Phenytoin: (Moderate) A dosage adjustment may be needed during coadministration of topiramate and hydantoins, closely monitor patients appropriately for increased adverse effects or altered clinical response to therapy. Serum phenytoin concentration may be needed for optimal dosage adjustments. Hydantoins have been shown to reduce topiramate serum concentrations. Topiramate may increase phenytoin concentrations through its inhibitory effects on CYP2C19. In some patients receiving phenytoin concurrently with topiramate, plasma concentrations of phenytoin were increased by 25% and topiramate plasma concentrations were decreased by 48%. These patients were generally receiving dosage regimens of phenytoin twice-daily. Other patients experienced a change of less than 10% in phenytoin plasma concentrations. A similar reaction would be expected with fosphenytoin.
Pioglitazone: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Pioglitazone; Glimepiride: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control.
Pioglitazone; Metformin: (Moderate) A decrease in the exposures of pioglitazone and its active metabolites were observed in a clinical trial during concurrent use of topiramate. The clinical significance is unknown; however, results of routine blood glucose monitoring should be carefully followed during coadministration of pioglitazone and topiramate to ensure adequate glucose control. (Moderate) Consider more frequent monitoring of patients receiving metformin and concomitant topiramate due to increased risk for lactic acidosis. Carbonic anhydrase inhibitors, such as topiramate, frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. In healthy volunteers, metformin Cmax and AUC increased by 17% and 25%, respectively, when topiramate was added, and oral plasma clearance of topiramate appears to be reduced when administered with metformin. The clinical significance of the effect on the pharmacokinetics of metformin or topiramate are not known.
Pregabalin: (Moderate) Monitor for respiratory depression and sedation during concomitant topiramate and pregabalin use; consider starting pregabalin at a low dose. Concomitant use increases the risk for additive CNS depression.
Primidone: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Probenecid: (Minor) Probenecid may increase the renal clearance of topiramate resulting in lower topiramate concentrations. Although not evaluated in humans, animal studies using probenecid along with topiramate showed a significant increase in renal clearance of topiramate. This suggests that topiramate may undergo renal tubular reabsorption. Probenecid may block renal tubular reabsorption of topiramate, thus increasing the renal clearance of the drug.
Probenecid; Colchicine: (Minor) Probenecid may increase the renal clearance of topiramate resulting in lower topiramate concentrations. Although not evaluated in humans, animal studies using probenecid along with topiramate showed a significant increase in renal clearance of topiramate. This suggests that topiramate may undergo renal tubular reabsorption. Probenecid may block renal tubular reabsorption of topiramate, thus increasing the renal clearance of the drug.
Prochlorperazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Progesterone: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Progestins: (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Promethazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Promethazine; Dextromethorphan: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Promethazine; Phenylephrine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Propantheline: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Protriptyline: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant protriptyline and topiramate use due to the risk for additive CNS depression.
Quazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Ramelteon: (Major) Although not specifically studied, coadministration of CNS depressant drugs with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Relugolix; Estradiol; Norethindrone acetate: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Remimazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Rilpivirine: (Moderate) Close clinical monitoring is advised when administering topiramate with rilpivirine due to the potential for rilpivirine treatment failure. Although this interaction has not been studied, predictions can be made based on metabolic pathways. Topiramate is an inducer of the hepatic isoenzyme CYP3A4; rilpivirine is metabolized by this isoenzyme. Coadministration may result in decreased rilpivirine serum concentrations and impaired virologic response.
Ritonavir: (Moderate) Concurrent administration of topiramate with ritonavir may result in decreased concentrations of ritonavir. Topiramate is not extensively metabolized, but is a mild CYP3A4 inducer. Ritonavir is metabolized by this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Romidepsin: (Moderate) Romidepsin is a substrate for CYP3A4. Coadministration of a CYP3A4 inducer, like topiramate, may decrease systemic concentrations of romidepsin. Use caution when concomitant administration of these agents is necessary.
Scopolamine: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Secobarbital: (Moderate) Although topiramate is not extensively metabolized (70% renally eliminated), an interaction with barbiturates via hepatic isoenzyme activity is possible. In patients receiving either phenobarbital or primidone in combination with topiramate, there was a < 10% change in phenobarbital or primidone plasma concentrations; the effects on topiramate plasma concentrations were not evaluated. Barbiturates may cause additive sedation or other CNS depressive effects when used concurrently with topiramate. When topiramate is combined with phentermine for the treatment of obesity, a greater risk of CNS depression exists. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as the barbiturates, may also increase the risk of bleeding; monitor patients appropriately.
Segesterone Acetate; Ethinyl Estradiol: (Major) Women taking both estrogens and topiramate should report breakthrough bleeding to their prescribers. If used for contraception, an alternate or additional form of contraception should be considered in patients prescribed topiramate, especially for patients receiving topiramate doses greater than 200 mg per day. Higher-dose hormonal regimens may be indicated where acceptable or applicable. The alternative or additional contraceptive agent may need to be continued for 1 month after discontinuation of topiramate. Patients taking these hormones for other indications may need to be monitored for reduced clinical effect while on topiramate, with dose adjustments made based on clinical efficacy. Concurrent administration may increase estrogen elimination. (Moderate) Patients taking progestin hormones for contraception may consider an alternate or additional form of contraception, such as nonhormonal and/or barrier methods, during and for 1 month following discontinuation of topiramate. Higher-dose hormonal regimens may also be considered. Monitor patients taking these hormones for other indications for reduced clinical effect while on topiramate; adjust drug dosage as appropriate based on clinical response. Progestins are CYP3A substrates and topiramate is a CYP3A inducer. Pharmacokinetic drug interaction studies have generally shown minimal impact on progestin concentrations especially at topiramate doses of 200 mg/day or less.
Sirolimus: (Moderate) Monitor sirolimus concentrations and adjust sirolimus dosage as appropriate during concomitant use of topiramate. Concomitant use may decrease sirolimus exposure and efficacy. Sirolimus is a CYP3A substrate and topiramate is a weak CYP3A inducer.
Sofosbuvir; Velpatasvir: (Major) Use caution when administering velpatasvir with topiramate. Taking these drugs together may decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate; topiramate is a weak inducer of CYP3A4.
Sofosbuvir; Velpatasvir; Voxilaprevir: (Major) Use caution when administering velpatasvir with topiramate. Taking these drugs together may decrease velpatasvir plasma concentrations, potentially resulting in loss of antiviral efficacy. Velpatasvir is a CYP3A4 substrate; topiramate is a weak inducer of CYP3A4.
Solifenacin: (Moderate) Through an additive effect, the use of topiramate with agents that may increase the risk for heat related disorders, such as solifenacin, may lead to oligohidrosis, hyperthermia, and/or heat stroke.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Sufentanil: (Moderate) Because the dose of the sufentanil sublingual tablets cannot be titrated, consider an alternate opiate if topiramate must be administered. Monitor for reduced efficacy of sufentanil injection and signs of opioid withdrawal if coadministration with topiramate is necessary; consider increasing the dose of sufentanil injection as needed. If topiramate is discontinued, consider a dose reduction of sufentanil injection and frequently monitor for signs or respiratory depression and sedation. Sufentanil is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease sufentanil concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
Telmisartan; Amlodipine: (Minor) Coadministration of CYP3A4 inducers with amlodipine can theoretically increase the hepatic metabolism of amlodipine (a CYP3A4 substrate). Caution should be used when CYP3A4 inducers, such as topiramate, are coadministered with amlodipine. Monitor therapeutic response; the dosage requirements of amlodipine may be increased.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Temazepam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Terbinafine: (Moderate) Caution is advised when administering terbinafine with topiramate. Although this interaction has not been studied by the manufacturer, and published literature suggests the potential for interactions to be low, taking these drugs together may alter the systemic exposure of terbinafine. Predictions about the interaction can be made based on the metabolic pathways of both drugs. Terbinafine is metabolized by at least 7 CYP isoenyzmes, with major contributions coming from CYP2C19 and CYP3A4; topiramate is an inducer of CYP3A4 and an inhibitor of CYP2C19. Monitor patients for adverse reactions and breakthrough fungal infections if these drugs are coadministered.
Thioridazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Tolterodine: (Moderate) Through an additive effect, the use of topiramate (a weak carbonic anhydrase inhibitor) with agents that may increase the risk for heat-related disorders, such as antimuscarinics, may lead to oligohidrosis, hyperthermia and/or heat stroke.
Torsemide: (Moderate) Monitor potassium concentration before and during concomitant topiramate and loop diuretic use due to risk for additive hypokalemia. Topiramate can increase the risk of hypokalemia through its inhibition of carbonic anhydrase activity and concomitant use with loop diuretics may further potentiate potassium-wasting.
Tramadol: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Tramadol; Acetaminophen: (Moderate) Reserve concomitant prescribing of opioids and other CNS depressants, such as topiramate, for use in patients in whom alternate treatment options are inadequate. Limit dosages and durations to the minimum required and monitor patients closely for respiratory depression and sedation. If concomitant use is necessary, consider prescribing naloxone for the emergency treatment of opioid overdose. Concomitant use can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Triazolam: (Moderate) Topiramate has the potential to cause CNS depression as well as other cognitive and/or neuropsychiatric adverse reactions. The CNS depressant effects of topiramate can be potentiated pharmacodynamically by concurrent use of CNS depressant agents such as the benzodiazepines.
Trifluoperazine: (Moderate) Monitor for unusual drowsiness and excess sedation during coadministration of phenothiazines and topiramate due to the risk for additive CNS depression.
Trihexyphenidyl: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Trimipramine: (Moderate) Monitor for unusual drowsiness or excess sedation during concomitant trimipramine and topiramate use due to the risk for additive CNS depression.
Trospium: (Moderate) Oligohidrosis and hyperthermia have been reported in post-marketing experience with topiramate. Use caution when topiramate is prescribed with agents known to predispose patients to similar heat-related disorders such as trospium.
Ulipristal: (Major) Avoid administration of ulipristal with drugs that induce CYP3A4. Ulipristal is a substrate of CYP3A4 and topiramate is a mild CYP3A4 inducer. Concomitant use may decrease the plasma concentration and effectiveness of ulipristal.
Valproic Acid, Divalproex Sodium: (Moderate) Concomitant administration of topiramate and valproic acid has been associated with hyperammonemia with or without encephalopathy in patients who have tolerated either drug alone. In addition, concomitant administration of topiramate and valproic acid has been associated with hypothermia with or without hyperammonemia in patients who have tolerated either drug alone. Assessment of blood ammonia levels may be advisable in patients presenting with symptoms of hypothermia. Concurrent use of topiramate and drugs that cause thrombocytopenia, such as valproic acid, may also increase the risk of bleeding; monitor patients appropriately. In several case reports, children with localized epilepsy have presented with somnolence, seizure exacerbation, behavioral alteration, decline in speech and cognitive abilities, and ataxia while being treated with a combination of valproate and topiramate. Previously, the children tolerated valproic acid with other antiepileptic drugs. Children presented with elevated serum ammonia, normal or elevated LFTs, and generalized slowing of EEG background activity during encephalopathy, which promptly reverted to normal along with clinical improvement following withdrawal of valproate. The possible mechanism is topiramate-induced aggravation of all the known complications of valproic acid monotherapy; it is not due to a pharmacokinetic interaction. This condition is reversible with cessation of either valproic acid or topiramate.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor serum potassium concentrations and for increased topiramate-related adverse effects during concomitant hydrochlorothiazide use. Concomitant use has been shown to increase topiramate exposure by 29% and may potentiate the potassium-wasting action of hydrochlorothiazide.
Vemurafenib: (Major) Concomitant use of vemurafenib and topiramate may result in decreased concentrations of vemurafenib. Vemurafenib is a CYP3A4 substrate and topiramate is a weak CYP3A4 inducer. Use caution and monitor patients for therapeutic effects.
Vorapaxar: (Moderate) Use caution during concurrent use of vorapaxar and topiramate. Decreased serum concentrations of vorapaxar and thus decreased efficacy are possible when vorapaxar, a CYP3A4 substrate, is coadministered with topiramate, a mild inducer of CYP3A4 in vitro. In addition, concurrent use of topiramate and drugs that affect platelet function such as platelet inhibitors may increase the risk of bleeding. In a pooled analysis of placebo-controlled trials, bleeding was more frequently reported in patients receiving topiramate (4.5%) compared to placebo (23%). In those with severe bleeding events, patients were often taking drugs that cause thrombocytopenia or affect platelet function or coagulation.
Warfarin: (Moderate) Closely monitor the INR if coadministration of warfarin with topiramate is necessary as concurrent use may decrease the exposure of warfarin leading to reduced efficacy; increased bleeding is also possible with the combination. Topiramate is a weak CYP3A4 inducer and the R-enantiomer of warfarin is a CYP3A4 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.
Zaleplon: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Zolpidem: (Moderate) Although not specifically studied, coadministration of CNS depressant drugs (e.g., anxiolytics, sedatives, and hypnotics) with topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents. Monitor for increased CNS effects if coadministering.
Zonisamide: (Moderate) Monitor for the appearance or worsening of metabolic acidosis if zonisamide is given concomitantly with topiramate. Concomitant use of zonisamide with another carbonic anhydrase inhibitor, like topiramate, may increase the severity of metabolic acidosis and may also increase the risks of hyperammonemia, encephalopathy, and kidney stone formation. Monitor serum ammonia concentrations if signs or symptoms of encephalopathy occur. Hyperammonemia resulting from zonisamide resolves when zonisamide is discontinued and may resolve or decrease in severity with a decrease of the daily dose.

EPRONTIA Oral Sol: 1mL, 25mg
Qudexy XR/Topiramate/Trokendi XR Oral Cap ER: 25mg, 50mg, 100mg, 150mg, 200mg
Topamax Sprinkle/Topiramate Oral Cap Coated Pellets: 15mg, 25mg
Topamax/Topiragen/Topiramate Oral Tab: 25mg, 50mg, 100mg, 200mg

400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.

400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.

17 years: 400 mg/day PO for epilepsy; 100 mg/day PO for migraine prophylaxis.
13 to 16 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy; 100 mg/day PO for migraine prophylaxis.

12 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy; 100 mg/day PO for migraine prophylaxis.
10 to 11 years: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing more than 38 kg: 400 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 23 to 38 kg: 350 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 12 to 22 kg: 300 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
2 to 9 years weighing 11 kg or less: 250 mg/day PO (monotherapy) or 9 mg/kg/day PO (adjunct therapy) for epilepsy.
Younger than 2 years: Safety and efficacy have not been established.

Safety and efficacy have not been established.

Safety and efficacy have not been established.

The exact mechanism of topiramate's anticonvulsant and migraine prophylaxis effects is unknown. It appears that topiramate may block the spread of seizures rather than raise the seizure threshold like other antiepileptic drugs (AEDs). The drug appears to have several mechanisms of action. First, topiramate reduces the duration of abnormal discharges and the number of action potentials within each discharge. This is probably secondary to its ability to block voltage-sensitive sodium channels. Second, topiramate enhances the activity of the inhibitory neurotransmitter gamma-aminobutyrate (GABA) at GABA-A receptors by increasing the frequency at which GABA activates GABA-A receptors. Third, topiramate inhibits excitatory transmission by antagonizing some types of glutamate receptors. Specifically, topiramate antagonizes the ability of kainate to activate the kainate/AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid; non-NMDA) subtype of excitatory amino acid (glutamate) receptor. There is no apparent effect on the activity of N-methyl-D-aspartate (NMDA) at the NMDA receptor subtype. Topiramate is also a weak carbonic anhydrase inhibitor (isozymes II and IV); however, while this action can cause a risk for metabolic acidosis, this mechanism does not appear to be involved in the anticonvulsant action of the drug.
 
In addition to its efficacy in epilepsy and migraine prophylaxis, topiramate has also demonstrated neuroprotective effects against hypoxic-ischemic brain damage in both in vitro and animal models. The cerebral damage of hypoxic-ischemic encephalopathy occurs in part due to an increased release of excitatory neurotransmitters, including glutamate. Glutamate activates AMPA receptors, depolarizes the cell, and promotes the removal of the voltage-sensitive magnesium block on NMDA receptors. This, in turn, promotes the entry of calcium into the cell, stimulating a series of reactions that lead to cell necrosis and apoptosis. The neuroprotective properties of topiramate appear to be primarily related to its inhibition of the kainate/AMPA subtype of glutamate receptors. In addition, blockade of sodium channels, high-voltage calcium currents, carbonic anhydrase isoenzymes, and mitochondrial permeability transition pore (MPTP) may also contribute to its neuroprotective effects.

Topiramate is administered orally. Protein binding ranges from 15% to 41% to over the concentration range of 0.5 to 250 mcg/mL. It is not metabolized to a great extent. Six metabolites have been identified and are formed via hydroxylation, hydrolysis, and glucuronidation. None of these metabolites constitutes more than 5% of an administered dose. About 70% of an administered dose is eliminated unchanged in the urine. Topiramate undergoes renal tubular reabsorption. Oral plasma clearance (CL/F) is approximately 20 to 30 mL/minute in adults after oral administration. Steady-state concentrations are reached in 4 and 5 days with immediate-release formulations and extended-release capsules (Qudexy XR), respectively, in adult patients with normal renal function. The mean plasma elimination half-life is 21 hours after single or multiple doses of immediate-release tablets or capsules. The mean effective half-life of extended-release capsules (Qudexy XR) is about 56 hours. The mean elimination half-life of topiramate was approximately 31 hours after repeat administration of extended-release capsules (Trokendi XR).
 
Affected cytochrome P450 isoenzymes and drug transporters: CYP2C19, CYP3A4
In vitro studies indicate that topiramate may induce CYP3A4 (weak inducer) and inhibit CYP2C19 (weak inhibitor). Topiramate does not inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, CYP3A4/5 isozymes. Some hepatic enzyme-inducing antiepileptic drugs (i.e., phenytoin, carbamazepine) have been shown to reduce topiramate serum concentrations by 40% to 48%.

Topiramate can cause fetal harm when administered to a pregnant woman. Consider the benefits and risks of topiramate in women of childbearing potential, particularly when it is being considered for conditions not usually associated with permanent injury or death. Counsel women of childbearing potential regarding the potential risk to the fetus from topiramate exposure, and consider alternative therapeutic options in women who are planning a pregnancy. Data from pregnancy registries indicate infants exposed to topiramate during pregnancy have an increased risk for cleft lip and/or cleft palate. The prevalence of oral clefts among topiramate-exposed infants was 1.4% compared to 0.3% in infants exposed to another antiepileptic drug (AED), and 0.11% in infants with mothers without epilepsy or AED exposure. The relative risk of oral clefts in topiramate-exposed pregnancies was 12.5 (95% CI 5.9 to 26.37) compared to untreated women.[28378] [55675] Oral clefts develop in the first trimester before many women know that they are pregnant.[43569] Data from pregnancy registries indicate infants exposed to topiramate during pregnancy have an increased risk for being small for gestational age (SGA), defined as a birth weight below the tenth percentile. SGA has been seen at all doses and appears to be dose-dependent. SGA occurs more frequently in infants of women who received higher topiramate doses or continued topiramate use until later in pregnancy (i.e., third trimester). According to registry data, the prevalence of SGA was 19.7% to 25% in topiramate-exposed infants compared to 7.9% in infants exposed to a reference AED, and 5.4% to 9% in infants with mothers without epilepsy or AED exposure. Excluding oral clefts, no other specific patterns of major congential malformations were observed based on data from pregnancy registries. The prevalence of major congenital malformations among topiramate-exposed infants was 4.1% compared to 1.8% in infants exposed to another AED, and 1.1% in infants with mothers without epilepsy or AED exposure. Registry data and findings from other studies suggest that combination therapy with AEDs may increase the risk of teratogenic effects compared to monotherapy with an AED. Structural malformations such as craniofacial defects and reduced fetal weight occurred in the offspring of multiple animal species during studies of topiramate. Topiramate can cause metabolic acidosis which, when occurring during pregnancy, has been associated with decreased fetal growth, decreased fetal oxygenation, fetal death, and may impact the ability of the fetus to tolerate labor. Monitor women taking topiramate during pregnancy for metabolic acidosis and treat as in the nonpregnant state. Monitor newborns of mothers treated with topiramate for metabolic acidosis after birth. Limited data indicate topiramate may be associated with pre-term labor and premature delivery. There is a pregnancy exposure registry that monitors outcomes in pregnant patients exposed to topiramate; information about the registry can be obtained at www.aedpregnancyregistry.org or by calling 1-888-233-2334.[28378] [55675]