Comparative Pharmacology
Head-to-head clinical analysis: EQUETRO versus PHENYTOIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: EQUETRO versus PHENYTOIN.
EQUETRO vs PHENYTOIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Equetro (carbamazepine extended-release) is an anticonvulsant and mood stabilizer. It stabilizes the inactivated state of voltage-gated sodium channels, thereby inhibiting repetitive neuronal firing and reducing synaptic transmission. It also potentiates GABA receptors and inhibits glutamate release.
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: 50 mg orally twice daily; increase by 50-100 mg/day every 2-4 weeks. Usual maintenance: 100-200 mg orally twice daily. Maximum: 200 mg orally twice daily.
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."
Carbamazepine: 25-65 hours (initial single dose), 12-17 hours (chronic dosing due to autoinduction); carbamazepine-10,11-epoxide: 5-8 hours.
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: 2% excreted unchanged (carbamazepine) in urine; 15% as carbamazepine-10,11-epoxide; 30% as other metabolites; biliary/fecal: 50-60% as metabolites.
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