Phenytoin Injection

  • Seizure disorders

Phenytoin Injection Generic Name & Formulations

General Description

Phenytoin 50mg/mL; contains alcohol, propylene glycol.

Pharmacological Class


How Supplied

Contact supplier.

Phenytoin Injection Indications


Status epilepticus (tonic-clonic). Seizure prophylaxis and treatment in neurosurgery.

Phenytoin Injection Dosage and Administration


Status epilepticus: IV not to exceed 50mg/min. Loading dose: 10–15mg/kg followed by maintenance doses of 100mg orally or IV every 6–8 hrs. Do not dilute solution in IV fluids. Neurosurgical procedures: see full labeling.


Status epilepticus: IV not to exceed 1–3mg/kg/min. Loading dose: 15–20mg/kg. Neurosurgical procedures: see full labeling.

Phenytoin Injection Contraindications


History of prior acute hepatotoxicity due to phenytoin. Heart block and sinus bradycardia. Adams-Stokes syndrome. Concomitant delavirdine.

Phenytoin Injection Boxed Warnings

Not Applicable

Phenytoin Injection Warnings/Precautions


Increased cardiovascular risk associated with rapid infusion; monitor during and after therapy; rate reduction or discontinuation may be needed. Hypotension. Severe myocardial insufficiency. Monitor ECG, BP, respiration, phenytoin levels. Diabetes. Change dose gradually. Monitor for signs/symptoms of serious dermatological reactions; discontinue if rash develops. Maintain proper dental hygiene. Oral contraception. Porphyria. Renal and/or hepatic impairment. Hypoalbuminemia. Elderly. Debilitated. Pregnancy (see full labeling). Nursing mothers.

Phenytoin Injection Pharmacokinetics

See Literature

Phenytoin Injection Interactions


See Contraindications. Potentiated by acute alcohol ingestion, amiodarone, benzodiazepines (eg, chlordiazepoxide, diazepam), chloramphenicol, dicumarol, disulfiram, estrogens, fluoxetine, halothane, H2 blockers (eg, cimetidine), isoniazid, methylphenidate, phenothiazines, phenylbutazone, salicylates, succinamides (eg, ethosuximide), sulfonamides, tolbutamide, trazodone, others. Antagonized by chronic alcohol ingestion, carbamazepine, reserpine, others. Antagonizes tricyclic antidepressants, oral anticoagulants, oral contraceptives, estrogens, corticosteroids, doxycycline, digitoxin, furosemide, theophylline, rifampin, quinidine, vitamins D and K, others. Variable effects with phenobarbital, valproic acid, divalproex, others. Absorption decreased by calcium.

Phenytoin Injection Adverse Reactions

Adverse Reactions

Nystagmus, drowsiness, dizziness, insomnia, dyskinesias, ataxia, GI disturbances, gingival hyperplasia, osteomalacia, blood dyscrasias, atrial and ventricular conduction depression, slurred speech, lymphadenopathy, hepatic disease, rash, hyperglycemia, SLE, hypertrichosis, immunoglobulin abnormalities; DRESS, multiorgan hypersensitivity (may be fatal), local toxicity (eg, purple glove syndrome).

Phenytoin Injection Clinical Trials

See Literature

Phenytoin Injection Note

Not Applicable

Phenytoin Injection Patient Counseling

See Literature