Effect of lansoprazole on intragastric pH. Comparison between morning and evening dosing.

Lansoprazole is a newly developed proton pump inhibitor. The purpose of this study was to determine whether morning or evening dosage gave better control of 24-hr intragastric pH. In this study, we examined the antisecretory effect of lansoprazole by repeated intragastric pH monitoring on four occasions in eight normal subjects and compared median 24-hr pH values and pH threshold time of pH greater than or equal to 4 between morning and evening dosing, following the administration of lansoprazole 30 mg once daily in either the morning or evening for seven days. Intragastric pH was monitored before and after seven days of treatment. Both morning and evening dosing caused a rise in the intragastric pH. Median pH for 24 hr was 4.3 and 1.6 with and without lansoprazole morning dosing and 4.6 and 2.1 for evening dosing, respectively. The pH threshold curve shifted to the right with lansoprazole treatment in either case. However, no differences were found between morning and evening dosing in terms of median 24-hr pH values or pH threshold time of pH greater than or equal to 4. These results indicate that lansoprazole can be given once daily in either the morning or evening because of its potent and long-lasting antisecretory activity.