Comparative Pharmacology
Head-to-head clinical analysis: PHENYTOIN versus VIGAFYDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PHENYTOIN versus VIGAFYDE.
PHENYTOIN vs VIGAFYDE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
Irreversible inhibitor of GABA transaminase, increasing brain GABA levels.
Oral: 300-400 mg/day in 3-4 divided doses; IV: 15-20 mg/kg loading dose, then 300 mg/day maintenance.
Adults: 50 mg/kg/day orally divided twice daily; maximum dose 3 g/day.
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."
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.
Terminal elimination half-life is 6-8 hours in adults; in neonates, it is prolonged to 16-20 hours due to immature renal function.
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%.
Renal excretion of unchanged drug accounts for approximately 65-70% of elimination; biliary/fecal excretion is minimal (<5%).
Category D/X
Category C
Anticonvulsant
Anticonvulsant