PHARMACOKINETICS AND ABSOLUTE BIOAVAILABILITY OF LANSOPRAZOLE

Objective: In a crossover study 12, healthy volunteers received lansop razole 15 mg or 30 mg orally, or 15 mg intravenously in randomized ord er as a single dose. Blood samples were taken and plasma levels of lan soprazole were determined using an HPLC method. The volunteers were ph enotyped for the debrisoquine/sparteine and mephenytoin polymorphisms. Results: The total clearance was 517 ml . min(-1), and the absolute b ioavailability was 91% for the 30-mg and 81% for the 15-mg enteric-coa ted formulation. The elimination half-life was about 1 h. No correlati on of the plasma levels to the sparteine metabolic ratio was found, an d no correlation to the mephenytoin type could be established, since a ll volunteers of the mephenytoin type were extensive metabolizers. Alt hough considerable variation, inter- and intraindividually, was observ ed, the increase in c(max) and AUC did not deviate from dose proportio nality. The present galenic formulation ensures a high bioavailability after a single dose.