Abstract
Pharmacokinetics of phenytoin were studied in healthy subjects. In a crossover study
five volunteers received either a single oral dose (300 mg) of phenytoin alone or
in combination with multiple doses of piperine (20 mg × 7 days) followed by an oral
dose of phenytoin. Blood samples were collected at 0.5, 1,2,3,4,8,12,24, and 48 h
after drug administration and analysed for phenytoin by the enzyme multiplied immunoassay
technique (EMIT). The results obtained revealed that a single daily dose of piperine
for 7 days decreased the absorption halflife (P < 0.05), prolonged the elimination
halflife (P < 0.01), and produced a higher area under the drug concentration curve
(P < 0.05) in comparison to phenytoin alone. It is therefore concluded that piperine
on multiple dose administration alters the pharmacokinetic parameters of the antiepileptic.
