Comparative Pharmacology
Head-to-head clinical analysis: PHENYTOIN SODIUM versus TEGRETOL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PHENYTOIN SODIUM versus TEGRETOL.
PHENYTOIN SODIUM vs TEGRETOL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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. Prolongs inactivation of voltage-gated sodium channels, reducing repetitive firing of action potentials.
Voltage-gated sodium channel blocker; stabilizes neuronal membranes and inhibits repetitive firing. Also inhibits glutamate release and enhances GABA activity.
Loading dose: 15-20 mg/kg IV (not to exceed 50 mg/min) or oral (1000-1500 mg total in divided doses). Maintenance: 300-400 mg/day PO in 1-2 divided doses or IV (100 mg every 6-8 hours).
Initial: 200 mg orally twice daily; increase by 200 mg/day at weekly intervals. Maintenance: 800-1200 mg/day in 2-4 divided doses. Maximum dose: 1600 mg/day. Extended-release: 200-400 mg twice daily.
None Documented
None Documented
Mean terminal half-life 22 ± 9 hours (range 7–42 hours), dose-dependent and saturable due to Michaelis-Menten kinetics; half-life increases with higher serum concentrations. Steady state achieved after 7–10 days.
Single dose: 25–65 hours (mean ~35 h); chronic therapy: 12–17 hours due to autoinduction; clinical context: requires 3–4 weeks to reach steady-state after dose adjustment.
Primarily hepatic metabolism (CYP2C9, CYP2C19); <5% excreted unchanged in urine. Metabolites (majority p-HPPA) are excreted renally as glucuronide conjugates. Fecal elimination negligible (<2%).
Primarily hepatic metabolism; ~72% excreted in urine (as metabolites, <2% unchanged), ~28% excreted in feces via bile.
Category D/X
Category C
Anticonvulsant
Anticonvulsant