Contraindicated in:
Use Cautiously in:
Exercise Extreme Caution in:
CV: hypotension (with rapid IV administration), tachycardia.
Derm: pruritus, ACUTE GENERALIZED EXANTHEMATOUS PUSTULOSIS, DRUG REACTION WITH EOSINOPHILIA AND SYSTEMIC SYMPTOMS (DRESS), purple glove syndrome, rash, STEVENS-JOHNSON SYNDROME, TOXIC EPIDERMAL NECROLYSIS.
EENT: amblyopia, deafness, diplopia, tinnitus.
GI: dry mouth, nausea, taste perversion, tongue disorder, vomiting.
Hemat: lymphadenopathy, megaloblastic anemia, pure red cell aplasia.
MS: back pain.
Neuro: ataxia, dizziness, drowsiness, nystagmus, agitation, brain edema, dysarthria, extrapyramidal syndrome, headache, hypoesthesia, incoordination, paresthesia, stupor, tremor, vertigo.
Misc: ANGIOEDEMA, pelvic pain.
Drug-Drug:
Drug-Natural Products:
Status Epilepticus
Nonemergent and Maintenance Dosing
Absorption: Rapidly converted to phenytoin after IV administration and completely absorbed after IM administration.
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: Fosphenytoin: 95–99%; phenytoin: 90–95%.
Metabolism/Excretion: Mostly metabolized by the liver via the CYP2C9 isoenzyme, and to a lesser extent by the CYP2C19 isoenzyme; the CYP2C9 isoenzyme exhibits genetic polymorphism (intermediate or poor metabolizers may have significantly ↑ fosphenytoin concentrations and an ↑ risk of adverse reactions).; minimal amounts excreted in the urine.
Half-life: Fosphenytoin: 15 min; phenytoin: 22 hr (range 7–42 hr).
(anticonvulsant effect)
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| IM | unknown | 30 min | up to 24 hr |
| IV | 15–45 min | 15–60 min | up to 24 hr |
NDC Code*
