Therapeutic Classification: antiarrhythmics (group IB), anticonvulsants
Pharmacologic Classification: hydantoins
REMS
Absorption: Absorbed slowly from the GI tract. Bioavailability differs among products; the Dilantin and Phenytek preparations are considered to be "extended" products. Other products are considered to be prompt release.
Distribution: Distributes into CSF and other body tissues and fluids. Enters breast milk; crosses the placenta, achieving similar maternal/fetal levels. Preferentially distributes into fatty tissue.
Protein Binding: Adults 9095%; ↓ protein binding in neonates (up to 20% free fraction available), infants (up to 15% free), and patients with hyperbilirubinemia, hypoalbuminemia, severe renal dysfunction or uremia.
Half-Life: 22 hr (range 742 hr).
(anticonvulsant effect)
ROUTE | ONSET | PEAK | DURATION |
---|---|---|---|
PO | 224 hr (1 wk)* | 1.53 hr | 612 hr |
PO-ER | 224 hr (1 wk) | 412 hr | 1236 hr |
IV | 0.51 hr (1 wk) | rapid | 1224 hr |
*() = time required for onset of action without a loading dose.
Contraindicated in:
Use Cautiously in:
CV: hypotension (↑ with IV phenytoin), bradycardia, CARDIAC ARREST, tachycardia
Derm: hypertrichosis, rash, ACUTE GENERALIZED EXANTHEMATOUS PUSTULOSIS, DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS (DRESS), exfoliative dermatitis, pruritus, purple glove syndrome, STEVENS-JOHNSON SYNDROME (SJS), TOXIC EPIDERMAL NECROLYSIS (TEN)
GI: gingival hyperplasia, nausea, constipation, drug-induced hepatitis, HEPATIC FAILURE, vomiting
Hemat: AGRANULOCYTOSIS, APLASTIC ANEMIA, leukopenia, lymphadenopathy, megaloblastic anemia, pure red cell aplasia, thrombocytopenia
MS: osteomalacia, osteoporosis
Neuro: ataxia, agitation, confusion, dizziness, drowsiness, dysarthria, dyskinesia, extrapyramidal syndrome, headache, insomnia, SUICIDAL THOUGHTS, vertigo, weakness.
Misc: ANGIOEDEMA, fever
Drug-drug:
Drug-Natural Products:
Anticonvulsant
Antiarrhythmic
Lab Test Considerations:
Toxicity and Overdose:
IV Administration:
NDC Code