Comparative Pharmacology
Head-to-head clinical analysis: CARBATROL versus PHENYTOIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CARBATROL versus PHENYTOIN.
CARBATROL vs PHENYTOIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Stabilizes neuronal membranes by blocking voltage-gated sodium channels, inhibiting repetitive firing of action potentials. Also enhances GABAergic activity.
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.
Initial dose 200 mg orally twice daily, increase by 200 mg/day at weekly intervals; maintenance 800-1200 mg/day in 2 divided doses extended-release capsules.
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 25-65 hours initially, then 12-17 hours after autoinduction; clinical context: requires dose adjustment after 3-5 weeks.
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: 70% as metabolites (including carbamazepine-10,11-epoxide) and 2-3% as unchanged drug; biliary/fecal: 30%.
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