Abstract: AIM: To compare the effects between different doses of rabeprazole(RAB) sodium for injection and 40 mg of omeprazole(OME) sodium for injection on 24-hour intragastric pH in healthy subjects. METHODS: In this open, paralleled, multi-center study, 84 healthy volunteers were divided into 4 groups. They were administered with intravenous dripping of 10 mg(Group A),20 mg(Group B) and 40 mg(Group C) per day of RAB and 40 mg(Group D) per day of OME respectively for 5 days. The values of intragastric pH of each subject were monitored for 24 h on the first day and the last day. RESULTS: The median 24 h intragastric pH values: the pH values on day 5 were significantly increased compared with those on day 1 (P<0.05). The mean percentage of the gastric pH>4 and pH>6 on day 5 were significantly increased compared with those on day 1 (P<0.05). The mean percentage of the gastric pH>4 in Group C were higher than those in Group A on day 1(P<0.05); and the mean percentage of the gastric pH>6 in Group D was higher than those in Groups A and B on day 5(P<0.05). CONCLUSION: Both RAB and OME sodium for injection have great inhibitory effect on gastric acid secretion. Continuous administration can more significantly inhibit the gastric acid than that of single-dose. The efficacy and drug potency of RAB 20 mg in gastric acid inhibition are similar to those of RAB 40 mg. The acid suppression is similar with single dose of RAB 10 mg, 20 mg, 40 mg and OME 40 mg. The roles of acid suppression are similar with continuous administration of three different doses of RAB. Besides, gender does not affect the pharmacodynamic action of the drugs.

Key words: Rabeprazole sodium for injection, Omeprazole sodium for injection, 24 h intragastric pH