Comparative Pharmacology
Head-to-head clinical analysis: DILANTIN versus GABITRIL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DILANTIN versus GABITRIL.
DILANTIN vs GABITRIL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Phenytoin 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 acts by blocking voltage-dependent sodium channels, thereby inhibiting the spread of seizure activity.
Tiagabine inhibits gamma-aminobutyric acid (GABA) reuptake into presynaptic neurons, thereby increasing synaptic GABA levels and enhancing inhibitory neurotransmission.
300–400 mg/day orally in 2–3 divided doses; IV loading dose 15–20 mg/kg at max 50 mg/min, then 300 mg/day IV divided 2–3 times daily.
Initial dose: 4 mg orally twice daily. Titrate by 4-8 mg/day every 2 weeks. Maximum dose: 56 mg/day in 2-4 divided doses.
None Documented
None Documented
Average 22 hours (range 7-42 hours) in adults. Dose-dependent; increases with higher concentrations due to saturable metabolism. In neonates: 10-15 hours. In chronic use, half-life may increase.
Terminal elimination half-life is 7–9 hours in healthy adults. In patients with hepatic impairment, half-life is prolonged (up to 12–24 hours) due to reduced clearance. No significant effect of renal impairment.
Primarily hepatic metabolism to inactive metabolites (p-hydroxyphenyltoin and glucuronide conjugate). Less than 5% excreted unchanged in urine. Fecal excretion minimal (<2%).
Approximately 70% of an oral dose is excreted in feces, 25% in urine, and 5% in bile. Renal elimination of unchanged drug is minimal (<2%); most is eliminated as metabolites.
Category C
Category C
Anticonvulsant
Anticonvulsant