Comparative Pharmacology
Head-to-head clinical analysis: CELONTIN versus CEREBYX.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CELONTIN versus CEREBYX.
CELONTIN vs CEREBYX
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Increases levels of gamma-aminobutyric acid (GABA) in the central nervous system, possibly by inhibiting GABA transaminase or enhancing GABA release; also reduces calcium influx into neurons, stabilizing neuronal membranes.
Fosphenytoin is a prodrug of phenytoin, which stabilizes neuronal membranes by blocking voltage-gated sodium channels, thereby inhibiting repetitive firing of action potentials.
300 mg orally three times daily, increased by 300 mg every 3-4 days as tolerated; usual maintenance dose 900-2400 mg/day in divided doses.
Loading dose: 15-20 mg PE/kg IV/IM (max 1500 mg PE); maintenance: 4-6 mg PE/kg/day IV/IM divided q12h or q8h. Switch to oral phenytoin at equivalent dose.
None Documented
None Documented
Terminal elimination half-life: 40-60 hours in adults, 30-45 hours in children; prolonged liver disease or renal impairment may increase half-life.
The terminal elimination half-life of fosphenytoin (converted to phenytoin) is approximately 15 hours (range 10-20 hours) in adults with normal hepatic function; after conversion, phenytoin half-life is dose-dependent and averages 22 hours (range 7-42 hours) at therapeutic concentrations.
Renal: approximately 40-60% as unchanged drug; hepatic metabolism accounts for the remainder, with metabolites excreted renally.
Renal excretion of unchanged drug and metabolites accounts for approximately 80% of the dose; about 20% is eliminated in feces via biliary excretion.
Category C
Category C
Anticonvulsant
Anticonvulsant