Determining the optimal dose of lansoprazole injection by 24-hour intragastric pH monitoring

Two studies were performed on healthy adult males using 24-h intragastric pH monitoring to investigate the acid secretion inhibitory effects of the proton pump inhibitor lansoprazole in its injectable form (lansoprazole injection). In the first study (study 1), eight subjects received 30 mg once daily and 30 mg twice daily of lansoprazole injection by the crossover method. In the second study (study 2), 12 subjects received 15 and 30 mg twice daily of lansoprazole injection and 20 mg twice daily of a histamine H2-receptor antagonist using the crossover method. The results of study 1 showed that 30 mg once daily of lansoprazole injection was not able to achieve sufficient suppression of acid secretion, and the results of study 2 suggested that the effectiveness of the three treatment regimens studied in suppressing gastric acid secretion can be ranked as follows: lansoprazole 30 mg twice daily > lansoprazole 15 mg twice daily > H2-receptor antagonist 20 mg twice daily.