Comparative Pharmacology
Head-to-head clinical analysis: PROMPT PHENYTOIN SODIUM versus ZONISADE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMPT PHENYTOIN SODIUM versus ZONISADE.
PROMPT PHENYTOIN SODIUM vs ZONISADE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Phenytoin stabilizes neuronal membranes by promoting sodium channel inactivation, thereby reducing repetitive firing of action potentials and inhibiting the spread of seizure activity.
Zonisamide is a sulfonamide anticonvulsant. Its precise mechanism of action is unknown, but it is believed to inhibit voltage-sensitive sodium channels and reduce T-type calcium currents, thereby stabilizing neuronal membranes and suppressing neuronal hypersynchronization. It may also modulate GABA and glutamate neurotransmission.
Loading dose: 15-20 mg/kg (max 1500 mg) IV at a rate not exceeding 50 mg/min. Maintenance dose: 300-600 mg/day IV or orally in 3 divided doses. Adjust per therapeutic drug monitoring (target total phenytoin 10-20 mcg/mL).
100-200 mg orally every 8 hours; maximum 600 mg/day.
None Documented
None Documented
30-100 hours (average 40 hours) following IV administration; prolonged in hepatic impairment, neonates, and with enzyme inhibitors; shorter in children and with enzyme inducers.
Terminal elimination half-life: 63-69 hours in adults; allows once-daily dosing; steady-state achieved in 14-21 days
Primarily hepatic metabolism (CYP2C9) to inactive p-HPPH. Renal excretion as p-HPPH glucuronide (~60-70%) and unchanged drug (5%), with ~30% biliary/fecal elimination.
Renal: approximately 62% (35% unchanged, 27% as glucuronide conjugate); fecal: 3%; biliary: negligible
Category D/X
Category C
Anticonvulsant
Anticonvulsant