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Dilantin Infatabs (Parke-Davis), Dilantin-125 (Parke-Davis)
(Cap, Extended-Release [CER], Tab, Chewable [CTB]) Control of generalized tonic-clonic (grand mal) and complex partial (psychomotor, temporal lobe) seizures. Prevention and treatment of seizures during or following neurosurgery. (Sus) Control of tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures.
Adults: Individualize dose. Do not change dose at intervals <7-10 days. (CER) Divided Daily Dosage: Initial: 100mg tid. Maint: 100mg tid-qid. Titrate: May increase up to 200mg tid, if necessary. QD Dosing: May give 300mg qd if seizure is controlled on divided doses of three 100mg cap daily. LD (Clinic/Hospital): 1g in 3 divided doses (400mg, 300mg, 300mg) given 2 hrs apart. Start maint dose 24 hrs after LD. (CTB) Initial: 100mg tid. Maint: 300-400mg/day. Titrate: May increase to 600mg/day, if necessary. May chew or swallow tab whole. Not for qd dosing. (Sus) Initial: 125mg tid. Titrate: May increase to 5 tsp (625mg) daily, if necessary. Determine serum level for optimal dosage adjustment. Elderly: Decrease dose or frequency of dosing.
Pediatrics: Individualize dose. Initial: 5mg/kg/day in two or three equally divided doses. Maint: 4-8mg/kg/day. Max: 300mg/day. >6 Yrs: May require the minimum adult dose (300mg/day).
CER: (sodium) 30mg, 100mg; Sus: 125mg/5mL; CTB [Infatabs]: 50mg* *scored
(Sus) Coadministration with delavirdine.
Caution in switching patient from a product formulated with the free acid (eg, Sus, CTB) to a product formulated with the Na+ salt (eg, CER) and vice versa. CTB/Sus yield higher plasma levels than CER; dose adjustments and serum level monitoring may be necessary. Avoid abrupt withdrawal; may precipitate status epilepticus. May increase risk of suicidal thoughts/behavior; monitor for worsening of depression and any unusual changes in mood or behavior. Caution with porphyria, hepatic dysfunction, elderly, and gravely ill patients. Bleeding disorder in newborns may occur; give vitamin K to mother before delivery and to neonate after birth. May cause serious skin adverse events (eg, Stevens-Johnson syndrome [SJS], toxic epidermal necrolysis [TEN]); d/c if rash occurs. Chronic use has been associated with decreased bone mineral density (eg, osteoporosis, osteomalacia) and bone fractures. May produce confusional states (eg, delirium, psychosis, encephalopathy, or cerebral dysfunction) at levels above optimal range; reduce dose or d/c if symptoms persist. Avoid use for seizures due to hypoglycemia or other metabolic causes. Not effective for absence (petit mal) seizures. Caution in the interpretation of total phenytoin plasma concentrations with renal/hepatic disease. Avoid use as an alternative therapy in patients positive for HLA-B*1502. Caution with history of hypersensitivity to structurally similar drugs (eg, barbiturates, succinimides, oxazolidinediones). Hyperglycemia, hematopoietic complications (eg, thrombocytopenia, leukopenia, granulocytopenia, agranulocytosis, pancytopenia with or without bone marrow suppression), and lymphadenopathy (eg, lymph node hyperplasia, pseudolymphoma, lymphoma, Hodgkin's disease) reported. (Sus) Drug reaction with eosinophilia and systemic symptoms (DRESS)/multiorgan hypersensitivity reported; evaluate immediately if signs and symptoms (eg, rash, fever, lymphadenopathy) are present and d/c if alternative etiology cannot be established. Hepatic injury, including cases of acute hepatic failure, reported; d/c with acute hepatotoxicity. (CTB, CER) Anticonvulsant hypersensitivity syndrome (AHS) (eg, arthralgias, eosinophilia, fever, liver dysfunction, lymphadenopathy, rash) reported.
Nystagmus, ataxia, slurred speech, decreased coordination, confusion, dizziness, insomnia, transient nervousness, motor twitching, headaches, N/V, constipation, rash, hypersensitivity reactions.
See Contraindications. Increased levels with acute alcohol intake, amiodarone, antiepileptics (eg, felbamate, topiramate, oxcarbazepine), azoles (eg, fluconazole, ketoconazole, itraconazole, voriconazole), chloramphenicol, chlordiazepoxide, cimetidine, diazepam, disulfiram, estrogens, ethosuximide, fluorouracil, fluoxetine, fluvoxamine, H2-antagonists, halothane, isoniazid, methylphenidate, omeprazole, phenothiazines, salicylates, sertraline, succinimides, sulfonamides, ticlopidine, tolbutamide, trazodone, and warfarin. Decreased levels with chronic alcohol abuse, carbamazepine, reserpine, sucralfate. Decreases effects of azoles, corticosteroids, doxycycline, estrogens, furosemide, irinotecan, oral contraceptives, paclitaxel, paroxetine, quinidine, rifampin, sertraline, teniposide, theophylline, vitamin D, and warfarin. Phenobarbital, sodium valproate, valproic acid may increase or decrease levels. May decrease levels of HIV antivirals (eg, amprenavir, efavirenz, Kaletra, indinavir, nelfinavir, ritonavir, saquinavir), and antiepileptics. May increase or decrease levels of phenobarbital, sodium valproate, valproic acid. Calcium antacids decrease absorption; space dosing. Avoid with enteral feeding preparations and/or nutritional supplements. (CTB, CER) Increased levels with phenylbutazone and dicumarol. Decreased effects of coumarin anticoagulants and digitoxin. Moban brand molindone contains Ca2+ ions that interfere with absorption. TCAs may precipitate seizures. (Sus) Decreased levels with ritonavir, nelfinavir.
Category D, not for use in nursing.
Hydantoin; inhibits seizure activity by promoting Na efflux from neurons, stabilizing threshold against hyperexcitability caused by excessive stimulation of environmental changes capable of reducing membrane Na+ gradient. Reduces the maximal activity of the brain stem centers responsible for the tonic phase of the tonic-clonic (grand mal) seizures.
Absorption: (CTB, Sus) Tmax=1.5-3 hrs; (CER) Tmax=4-12 hrs. Distribution: Highly protein bound; found in breast milk. Metabolism: Liver (hydroxylation). Elimination: Bile (inactive metabolite), urine; T1/2=22 hrs, (CTB) T1/2=14 hrs.
Assess the etiology of seizure. Assess for previous hypersensitivity, family history of AHS, immunosuppression, presence of grave illness, impaired hepatic function, porphyria, pregnancy/nursing status, and possible drug interactions.
Monitor for signs/symptoms of skin rash (eg, SJS, TEN), lymphadenopathy, and hyperglycemia in diabetic patients. Monitor for occurrence of confused states (eg, delirium, psychosis, encephalopathy), osteomalacia, and serum levels in pregnant women. Monitor for emergence/worsening of depression, suicidal thoughts, and/or any unusual changes in mood/behavior.
Inform of the importance of strictly adhering to prescribed dosage regimen. Caution on use of other drugs or alcoholic beverages without consulting physician. Counsel about the early signs and symptoms of potential hematologic, dermatologic, hypersensitivity, or hepatic reactions and instruct to immediately contact physician if these develop. Instruct to maintain proper dental hygiene while on medication to minimize risk of gingival hyperplasia. Instruct to notify physician if suicidal thoughts or mood/behavior changes emerge. Advise females about dangers of using medication during pregnancy and apprise of the potential harm to fetus. Advise that Infatabs can either be chewed thoroughly before swallowing or swallowed whole. Encourage pregnant patients to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry.
Administration: Oral route. Storage: 20-25°C (68-77°F). Protect from moisture. (CER) Preserve in tight, light-resistant containers. (Sus) Protect from freezing and light.