Pharmacokinetics of antipyrine in epileptic patients

The pharmacokinetics of antipyrine were examined after oral and intravenous administration to 20 epileptic subjects receiving antiepileptic drug therapy. Bioavailability was essentially complete (mean bioavailability 101.2% +/- 14.4 (s.d.] indicating that even in enzyme induced subjects, antipyrine behaves as a restrictively eliminated compound with negligible presystemic elimination in the gut or liver. Of the generally used measures of enzyme induction (oral clearance, oral half-life and intravenous half-life) oral clearance was the most closely related to the intravenous clearance of antipyrine (r = 0.919, P less than 0.001). Oral antipyrine administration is an alternative to intravenous administration in epileptic subjects who are enzyme-induced.