Comparative Pharmacology
Head-to-head clinical analysis: PARADIONE versus PHENYTOIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PARADIONE versus PHENYTOIN.
PARADIONE vs PHENYTOIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Paradione (paramethadione) is an oxazolidinedione anticonvulsant that suppresses neuronal activity in the motor cortex by increasing the threshold for repetitive neuronal firing and reducing synaptic transmission. Its exact mechanism is unclear but involves modulation of T-type calcium channels and enhancement of GABAergic inhibition.
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.
100 mg orally three times daily; maximum 600 mg/day.
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."
12-24 hours (terminal); prolonged in renal impairment
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: 70% unchanged; biliary/fecal: 25%; metabolic: 5%
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