Background: Lansoprazole and omeprazole are proton pump inhibitors which both strongly inhibit acid secretion, resulting in a significant increase in serum gastrin levels. However, no direct comparison of recommended doses (20 mg for omeprazole and 30 mg for lansoprazole) has been reported so far. Our aims were to compare the effects of omeprazole 20 mg/day and lansoprazole 30 mg/day on intragastric acidity and serum gastrin concentration in 12 healthy volunteers.

Methods: The study was double-blind, randomized and placebo-controlled with a cross-over design. On the seventh day of each period, 24-hour intragastric pH was measured using a combined glass electrode placed in the proximal stomach. The last morning dose of each regimen was taken at the end of 24-hour pH monitoring; acid output and serum gastrin concentrations were then studied in the fasting state and after stimulation with pentagastrin (maximal acid output) and a meal (post-prandial gastrin response).

Results: Compared to placebo, both drug regimens induced a sustained increase of 24-hour intragastric pH and significantly decreased basal and pentagastrin-stimulated acid secretion. Lansoprazole 30 mg was slightly more effective than omeprazole 20 mg in terms of time spent above pH 3 (P < 0.05). Accordingly post-prandial gastrin concentrations rose slightly more after lansoprazole than after omeprazole. All other differences were insignificant.

Conclusions: Both lansoprazole 30 mg and omeprazole 20 mg induce potent and long-lasting acid inhibition, with few minor differences when the two proton pump inhibitors are used at standard doses.