Comparative Pharmacology
Head-to-head clinical analysis: CEREBYX versus DEPAKOTE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CEREBYX versus DEPAKOTE.
CEREBYX vs DEPAKOTE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Fosphenytoin is a prodrug of phenytoin, which stabilizes neuronal membranes by blocking voltage-gated sodium channels, thereby inhibiting repetitive firing of action potentials.
Increases GABA levels by inhibiting GABA transaminase and succinic semialdehyde dehydrogenase; also blocks voltage-gated sodium channels and T-type calcium channels.
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.
Initial dose 750 mg/day PO in divided doses; increase by 250-500 mg/day every 3-7 days; maintenance dose 1000-2000 mg/day PO divided BID or TID; maximum 60 mg/kg/day.
None Documented
None Documented
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.
Terminal: 9-16 hours (mean 12 h); extended with hepatic dysfunction, co-administered enzyme inhibitors, or in elderly.
Renal excretion of unchanged drug and metabolites accounts for approximately 80% of the dose; about 20% is eliminated in feces via biliary excretion.
Renal: <3% as unchanged drug; >95% as metabolites (glucuronide conjugates, oxidation products). Biliary/fecal: minor, <5%.
Category C
Category C
Anticonvulsant
Anticonvulsant