Pharmacokinetics and pharmacodynamics of esomeprazole, the S‐isomer of omeprazole

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Abstract
Background: Esomeprazole, the S‐isomer of omeprazole, is the first proton pump inhibitor developed as a single isomer for the treatment of acid‐related diseases.Aim: To examine the pharmacokinetics and pharmacodynamics of esomeprazole.Methods: In a crossover study, 12 healthy males received 5, 10 or 20 mg of esomeprazole, or 20 mg of omeprazole, once daily over 5 days. The pharmacokinetics and effects on pentagastrin‐stimulated peak acid output of esomeprazole and omeprazole were studied on days 1 and 5.Results: The area under the curve (AUC) of both esomeprazole and omeprazole increased from day 1 to day 5. The correlation between acid inhibition and AUC for esomeprazole could be well described with a sigmoid Emax model. The mean inhibition values of the pentagastrin‐stimulated peak acid output on day 1 for 5, 10 and 20 mg of esomeprazole were 15%, 29% and 46%, respectively; the corresponding day 5 values were 28%, 62% and 90%. The mean inhibition values of the pentagastrin‐stimulated peak acid output for omeprazole were 35% (day 1) to 79% (day 5).Conclusions: The pharmacokinetics of esomeprazole are time and dose dependent. There was a good correlation between AUC and effect for esomeprazole. These data suggest an increased acid inhibitory effect of esomeprazole compared to omeprazole.