No

Anticonvulsant, Hydantoin

Treatment of tonic-clonic and partial seizures in patients who are uncontrolled with less toxic anticonvulsants; usually used in combination with other anticonvulsants

C

Hypersensitivity to mephenytoin, other hydantoins, or any component

>10%:

Central nervous system: Psychiatric changes, slurred speech, trembling, dizziness, drowsiness

Gastrointestinal: Constipation, nausea, vomiting

1% to 10%:

Central nervous system: Headache, insomnia

Dermatologic: Skin rash

Gastrointestinal: Anorexia, weight loss

Hematologic: Leukopenia

Hepatic: Hepatitis

Renal: Increase in serum creatinine

CYP2C19 enzyme substrate

Increased effect/toxicity with alcohol, sulfonamides, chloramphenicol, cimetidine, isoniazid, disulfiram, phenothiazines, benzodiazepines

Stabilizes neuronal membranes and decreases seizure activity by increasing efflux or decreasing influx of sodium ions across cell membranes in the motor cortex during generation of nerve impulses; prolongs effective refractory period and suppresses ventricular pacemaker automaticity, shortens action potential in the heart

Oral:

Adults: Initial dose: 50-100 mg/day given daily; increase by 50-100 mg at weekly intervals; usual maintenance dose: 200-600 mg/day in 3 divided doses; maximum: 800 mg/day

Alcohol: Additive CNS depression; has been reported with hydantoins; avoid or limit alcohol

Food:

Fresh fruits containing Vitamin C: Displaces drug from binding sites, resulting in increased urinary excretion of hydantoin; education patients regarding the potential for decreased anticonvulsant effect of hydantoins with consumption of foods high in Vitamin C

Glucose: Hyperglycemia and glycosuria may occur in patients receiving high-dose therapy; monitor blood glucose concentration, especially in patients with impaired renal function

Drowsiness and dizziness are common; may cause insomnia; may rarely cause confusion

May cause leukopenia; use caution with clozapine or carbamazepine; may induce hepatic enzymes; caution with concurrent psychotropics; monitor for altered response

No information available to require special precautions

Mephenytoin, like phenytoin, causes gingival hyperplasia. Usually starts during the first 6 months of dental treatment as gingivitis. The incidence is higher in patients under 20 years of age. To minimize severity and growth rate of gingival tissue begin a program of professional cleaning and patient plaque control within 10 days of starting anticonvulsant therapy. GH induced by mephenytoin disappears with cessation of drug therapy.

Take with food, avoid alcoholic beverages; may cause dizziness, drowsiness, and impair coordination or judgment

Monitor CBC and platelet

Tablet: 100 mg