Variable omeprazole kinetics in healthy Jordanian adults

Objectives . The objective of this study was to examine the pharmacokinetics of orally administered omeprazole in healthy adult Jordanian men. Method . Plasma concentrations of omeprazole were measured over a 12 h period after administration of a single oral dose of 40 mg omeprazole (Losec ® , AstraZeneca, UK). Subjects were healthy adult Jordanian men age 18–38 (24±4, mean±SD). The pharmacokinetic parameters were derived from the plasma concentration‐time profiles for AUC 0‐t , AUC 0‐inf , C max , t max , t 1/2e and K e . Results . The pharmacokinetic of omeprazole were scattered over a wide range. The median AUC 0‐inf was 784.86±1182.88 (ng·h/ml), and the median C max was 521±354 (ng/ml) (median±SD). In general, most subjects showed normal distribution (∼90%). Some subjects (10%) did show very high AUC and C max compared with the reported AUC and C max levels. These subjects had higher half‐lives and lower rates of elimination. Conclusion . Significant difference in the pharmacokinetics of omeprazole after a single dose administration was noted. Approximately 10% of the study group showed very high omeprazole plasma levels and AUC s. Differences in the pharmacokinetics might be due to differences in the genetic make‐up of subjects. Copyright © 2005 John Wiley & Sons, Ltd.