Seizure disorders:

Indications for CEREBYX:

Control of generalized tonic-clonic status epilepticus. Seizure prophylaxis and treatment in neurosurgery. Short-term substitution for oral phenytoin. Use only when oral phenytoin administration is not possible.

Adult:

Must prescribe and dispense fosphenytoin sodium inj doses, infusion rates and concentration in dosing solutions expressed as phenytoin sodium equivalents (PE); see full labeling. Max infusion rate: 150mg PE/min. ≥17yrs: status epilepticus: loading dose: 15–20mg PE/kg IV administered at 100–150mg PE/min; nonemergent loading dose: 10–20mg PE/kg IV or IM inj; maintenance dose: initially 4–6mg PE/kg/day. Substitution for oral phenytoin: give same total daily dose by IM or IV.

Children:

Must prescribe and dispense fosphenytoin sodium inj doses, infusion rates and concentration in dosing solutions expressed as phenytoin sodium equivalents (PE); see full labeling. Max infusion rate: 2mg PE/kg/min (or 150mg PE/min, whichever is slower). Birth to <17yrs: status epilepticus: loading dose: 15–20mg PE/kg IV administered at 2mg PE/kg/min (or 150mg PE/min, whichever is slower); nonemergent loading dose: 10–15mg PE/kg IV inj at 1–2mg PE/kg/min (or 150mg PE/min, whichever is slower); maintenance dose: 2–4mg PE/kg IV inj every 12hrs at 1–2mg PE/kg/min (or 100mg PE/min, whichever is slower). Substitution for oral phenytoin: give same total daily dose by IV. IM route should ordinarily not be used.

Contraindications:

Sinus bradycardia, sinoatrial block, or 2nd and 3rd degree A-V block. Adams-Stokes syndrome. Concomitant delavirdine. Prior history of acute hepatotoxicity attributable to Cerebyx or phenytoin.

Boxed Warning:

Cardiovascular risk associated with rapid infusion rates.

Warnings/Precautions:

Risk of dosing errors. Do not make adjustments in recommended doses when substituting fosphenytoin sodium injection for phenytoin sodium or vice versa. Increased risk of cardiac and local toxicity with rapid infusion; monitor during and after therapy; rate reduction or discontinuation may be needed; switch to oral phenytoin when possible. Hypotension. Severe myocardial insufficiency. Monitor ECG, BP, respiratory function, phenytoin levels. Risk of serious dermatologic reactions; discontinue and evaluate at 1st sign of a rash. Increased risk of SJS/TEN if HLA-B*1502 positive (esp. in Asians); avoid as an alternative for carbamazepine. Adjust dose gradually. Avoid abrupt cessation. Phosphate restricted. Renal and/or hepatic impairment. Hypoalbuminemia. Porphyria. Diabetes. Alcoholics. Slow metabolizers. Elderly. Debilitated. Pregnancy: avoid. Nursing mothers: not recommended.

Pharmacologic Class:

Hydantoin.

Interactions:

Potentiated by acute alcohol intake, amiodarone, antidepressants (eg, fluoxetine, fluvoxamine, sertraline), antiepileptics (eg, ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate), azoles, capecitabine, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluorouracil, fluvastatin, H2-antagonists, isoniazid, methylphenidate, omeprazole, phenothiazines, salicylates, sulfonamides, ticlopidine, tolbutamide, trazodone. Antagonized by antineoplastics (eg, bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate), antivirals (eg, fosamprenavir, nelfinavir, ritonavir), antiepileptics (eg, carbamazepine, vigabatrin), diazepam, diazoxide, folic acid, reserpine, rifampin, St. John’s wort, theophylline. Variable effects with phenobarbital, valproic acid, and valproate sodium. Antagonizes azoles, antineoplastics (eg, irinotecan, paclitaxel, teniposide), corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, vitamin D, HIV antivirals (eg, efavirenz, lopinavir/ritonavir, indinavir, nelfinavir, ritonavir, saquinavir), antiepileptics, atorvastatin, simvastatin, calcium channel blockers, others. Concomitant neuromuscular blockers (eg, pancuronium, vecuronium, rocuronium, cisatracurium); may need higher infusion rate. Variable PT/INR responses with concomitant warfarin. Concomitant fosamprenavir/ritonavir may potentiate amprenavir. Caution with drugs that are highly bound to serum albumin. May decrease T4 serum concentrations, or produce low results in dexamethasone or metyrapone tests. May increase serum concentrations of glucose, alkaline phosphatase and gamma glutamyl transpeptidase.

Adverse Reactions:

Adults: pruritus, nystagmus, dizziness, somnolence, ataxia; children: vomiting, nystagmus, ataxia; cardiovascular reactions (esp. after high doses or rapid IV), severe cutaneous adverse reactions (eg, SJS, TEN, AGEP, DRESS), multiorgan hypersensitivity, angioedema (discontinue if occurs), hypersensitivity reactions, hepatotoxicity (discontinue immediately; do not readminister), lymphadenopathy, sensory disturbances, local toxicity (eg, purple glove syndrome), hyperglycemia.

Generic Availability:

YES

How Supplied:

Vials 100mg PE/2mL—25; 500mg PE/10mL—10