Comparison of the effects of single and repeated oral doses of lansoprazole and rabeprazole on ambulatory 24-hour intragastric pH in healthy volunteers.

Background: As the comparative pharmacokinetics and pharmacodynamics of lansoprazole and rabeprazole have not previously been studied, we set out in this study to compare the pharmacokinetics and pharmacodynamics of single and repeated daily doses of lansoprazole 15 mg and 30 mg with those of rabeprazole 10 mg and 20 mg.

Methods: This was an open-label, randomised, crossover, two-centre study in 72 healthy volunteers. Each subject received each of the four treatments for 5 days, with 2-week washout periods. Continuous 24-hour intragastric pH and pharmacokinetics were studied on days 1 and 5.

Results: Mean 24-hour pH and percentage time for pH > 4 were not significantly different between lansoprazole 30 mg and rabeprazole 20 mg. Mean 24-hour pH and percentage time for pH > 4 were significantly greater after lansoprazole 30 mg and rabeprazole 20 mg than after lansoprazole 15 mg and rabeprazole 10 mg, respectively. Lansoprazole resulted in greater acid suppression during hours 0-5 on days 1 and 5, whereas rabeprazole had greater suppression during hours 11-24 on day 5. Time to maximum plasma concentration was significantly shorter for lansoprazole on both days.

Conclusion: Lansoprazole had a consistently faster onset of action, whereas rabeprazole had a greater effect during the evening hours after 5 days of administration.