Comparative Pharmacology
Head-to-head clinical analysis: DEPAKOTE CP versus PHENYTOIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DEPAKOTE CP versus PHENYTOIN.
DEPAKOTE CP vs PHENYTOIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Valproate increases GABA concentration in the brain by inhibiting GABA transaminase and succinic semialdehyde dehydrogenase. It also blocks voltage-gated sodium channels and T-type calcium channels.
Phenytoin is a hydantoin anticonvulsant that stabilizes neuronal membranes and decreases seizure activity by increasing efflux or decreasing influx of sodium ions across cell membranes in the motor cortex during generation of nerve impulses. It use-dependently blocks voltage-gated sodium channels, prolonging their inactivation phase and reducing high-frequency repetitive firing of action potentials.
250-500 mg orally twice daily, titrated by 250 mg/day every 3-7 days; maximum 60 mg/kg/day. Target trough serum concentration: 50-100 mcg/mL.
Oral: 300-400 mg/day in 3-4 divided doses; IV: 15-20 mg/kg loading dose, then 300 mg/day maintenance.
None Documented
None Documented
Clinical Note
moderatePhenytoin + Digoxin
"The metabolism of Digoxin can be increased when combined with Phenytoin."
Clinical Note
moderateFosphenytoin + Digoxin
"The metabolism of Digoxin can be increased when combined with Fosphenytoin."
Clinical Note
moderatePhenytoin + Digitoxin
"The metabolism of Digitoxin can be increased when combined with Phenytoin."
Clinical Note
moderateFosphenytoin + Digitoxin
"The metabolism of Digitoxin can be increased when combined with Fosphenytoin."
Terminal elimination half-life is 9-16 hours (mean ~12 hours) in adults; prolonged in hepatic impairment, elderly, and neonates.
Average terminal half-life 22 hours (range 7–42 hours) in adults; dose-dependent due to saturation of metabolism at therapeutic concentrations (10–20 mg/L). Half-life increases with higher doses.
Renal: 30-50% as glucuronide conjugates, 3% as unchanged drug; fecal: minimal; less than 3% excreted in bile.
Primarily hepatic metabolism (>95%); less than 5% excreted unchanged in urine. Renal excretion of metabolites (glucuronides) accounts for ~80% of elimination; biliary/fecal excretion of metabolites ~20%.
Category C
Category D/X
Anticonvulsant
Anticonvulsant