Fosphenytoin

DEA Class;  Rx

Common Brand Names; Cerebyx, Sesquient

Hypersensitivity to or its inactive ingredients, or to phenytoin or other hydantoins

Sinus bradycardia, sinoatrial block, 2nd or 3rd degree AV block, Adams-Stokes syndrome

Prior history of acute hepatotoxicity attributable to fosphenytoin or phenytoin

Coadministration with delavirdine

Adults and children

• Body as a whole: Fever, injection-site reaction, infection, chills, face edema, injection-site pain
• Cardiovascular: Hypertension
• Digestive: Constipation
• Metabolic and nutritional: Hypokalemia
• Musculoskeletal: Myasthenia; Infrequent: myopathy, leg cramps, arthralgia, myalgia
• Nervous: Reflexes increased, speech disorder, dysarthria, intracranial hypertension, thinking abnormal, nervousness
• Respiratory: Pneumonia
• Skin and appendages: Rash

IV, adults

• Pruritus (49%)
• Nystagmus (44%)
• Dizziness (31%)
• Somnolence (20%)
• Ataxia (11%)

IV, children and adolescents

• Vomiting (21%)
• Nystagmus (18%)

IM

• Nystagmus (15%)

Do NOT give IM for status epilepticus initial dose

Renal, hepatic or other hypoalbuminemic disease: monitor unbound phenytoin concentration

Do not abruptly discontinue antiepileptic drugs because of the possibility of increased seizure frequency, including status epilepticus; in the event of an allergic or hypersensitivity reaction, rapid substitution of alternative therapy may be necessary

Associated with exacerbation of porphyria; exercise caution when fosphenytoin is used in patients with this disease

Hyperglycemia, resulting from phenytoin’s inhibitory effect on insulin release, reported; phenytoin may also raise serum glucose concentrations in diabetic patients

Do not discontinue antiepileptic drugs abruptly because of possibility of increased seizure frequency, including status epilepticus; reduce dose gradually when necessary; in the event of allergic or hypersensitivity reaction, rapid substitution of alternative therapy, not belonging to hydantoin chemical class is necessary

Cases of acute hepatotoxicity, including infrequent cases of acute hepatic failure, reported with phenytoin; discontinue and do not readminister if acute hepatotoxicity occurs

Consider phosphate load (0.0037 mmol phosphate/mg PE fosphenytoin) when treating patients who require phosphate restriction, such as those with severe renal impairment

Exposure of phenytoin may increase the risks for congenital malformations and other adverse developmental outcomes

Prenatal phenytoin exposure is associated with an increased incidence of major malformations, including orofacial clefts and cardiac defects

It is not known whether fosphenytoin is secreted in human milk

Following administration of phenytoin, phenytoin is secreted in human milk