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 (approximately 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 AUCs. Differences in the pharmacokinetics might be due to differences in the genetic make-up of subjects.