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phenytoin sodium (diphenylhydantoin sodium)
Dilantin Kapseals, Diphenylan (CA) Epanutin (UK), Phenytek (CA)
Pharmacologic class: Hydantoin derivative
Therapeutic class: Anticonvulsant
Pregnancy risk category D
Thought to limit seizure activity by promoting sodium efflux from neurons in motor cortex and reducing activity in brainstem centers responsible for tonic phase of tonic-clonic seizures
Capsules (prompt-release): 30 mg, 100 mg
Capsules (extended-release): 30 mg, 100 mg
Injection: 50 mg/ml in 2- and 5-ml ampules
Oral suspension: 30 mg/5 ml, 125 mg/5 ml
Tablets (chewable): 50 mg
⊘Indications and dosages
➣ Status epilepticus
Adults: Loading dose of 10 to 15 mg/kg by slow I.V., then a maintenance dosage of 100 mg P.O. or I.V. q 6 to 8 hours
Neonates and children: Loading dose of 15 to 20 mg/kg I.V. in divided doses of 5 to 10 mg/kg
➣ Generalized tonic-clonic (grand mal) and complex partial (psychomotor, temporal lobe) seizures
Adults: Loading dose of 1 g P.O. (extended-release) in three divided doses (400 mg, 300 mg, and 300 mg) at 2-hour intervals in hospitalized patients requiring rapid steady-state serum levels (when I.V. route isn't desired). Maintenance dosing usually starts 24 hours after loading dose. Patients who haven't had previous treatment usually start at 100 mg (125 mg suspension) P.O. t.i.d., adjusted as needed to a maximum of 600 mg (625 mg suspension) P.O. daily. Alternatively, if divided doses control seizures, one daily dose of 300 mg P.O. (extended-release phenytoin sodium).
Children: Initially, 5 mg/kg/day P.O. in two or three equally divided doses; maintenance dosage individualized and given in two to three divided doses (not to exceed 300 mg/day).
➣ To prevent seizures during neuro-surgery
Adults: 100 to 200 mg I.M. at 4-hour intervals