THE EFFECTS OF ORAL DOSES OF LANSOPRAZOLE AND OMEPRAZOLE ON GASTRIC PH

We compared gastric pH values after therapeutic doses of lansoprazole and omeprazole in 17 healthy adult men. The pharmacokinetics of the tw o drugs were studied. A three-way crossover design compared the effect s on gastric pH of 15 and 30 mg lansoprazole and 20 mg omeprazole-each given once daily for 5 days. Ambulatory 24-h intragastric pH levels w ere measured before dosing, after the first and fifth doses in each pe riod, and 15 days after each dosing period. A positive relationship be tween the lansoprazole or omeprazole area under the curve (AUCs) and t he 24-h mean pH values was found for each regimen. No differences in m aximum concentration (C-max) and AUC were noted from day 1 to day 5 fo r the two lansoprazole doses. With omeprazole, both C-max and AUC leve ls were greater on day 5 than on day 1. All three regimens increased 2 4-h mean gastric pH, although 30 mg lansoprazole had the most signific ant effect. The percentage of time that gastric pH was >3, >4, and >5 was also significantly higher with 30 mg lansoprazole. All three regim ens were associated with reversible elevations of serum gastrin, which more than doubled at some points. No clinically significant adverse e vents were documented.