Population pharmacokinetics of omeprazole in a random Iranian population

Background: omeprazole is metabolized predominantly by cyp2c19, a polymorphically expressed enzymes that show marked interindividual and interethnic variation. these variations cause a substantial differences that have been reported in the pharmacokinetics of omeprazole. the aim of the present study was to evaluate the pharmacokinetic parameters of omeprazole in a random iranian population.methods: from the 20 subjects, only 17 healthy unrelated individuals of either sex (9 females age range 22-24 years) participated in the study. after an overnight fasting, a sample of blood was collected. the subjects received a single oral dose of 40 mg capsule of omeprazole (losec) and blood samples were taken up to 8 hours. omeprazole was analyzed by the hplc method and population pharmacokinetic analysis was performed using population pharmacokinetic modelling software p-pharm.results: the mean value for apparent plasma clearance (cl/f) was 20.8±6.9 (l.h-1). the corresponding value for apparent volume of distribution (v/f), and t1/2 beta were 21.6±7.5 (l) and 0.8±0.3 (h), respectively. a comparison of the weight normalized v/f and cl/f of omeprazole between males and females revealed that both parameters were significantly higher in females than males (p≤0.03).conclusion: these results show a substantial interindividual variability in omeprazole pharmacokinetics and this might affect the therapeutic effects of omeprazole as reported previously.