Effect of repeated injection and continuous infusion of omeprazole and ranitidine on intragastric pH over 72 hours

Abstract

Objective: In healthy subjects and patients with bleeding peptic ulcers, ranitidine and omeprazole, given parenterally, achieve high intragastric pH values on the first day of therapy. However, data on the antisecretory effect beyond the first 24 h is scanty. In addition, the superiority of either infusion or injection of omeprazole remains unproven. Thus, we have compared the antisecretory effect of high dose omeprazole and ranitidine infusion and injection over the critical first 72 h. Methods: A total of 34 healthy volunteers were randomized into a double-blind crossover 72 h intragastric pH-metry study (data compared: median pH, percentage of time with pH >4 and pH >6). Omeprazole-infusion: initial bolus of 80 mg + 8 mg/h; omeprazole-injection: initial bolus of 80 mg + 40 mg/6 h; Ranitidine-infusion: initial bolus of 50 mg + 0.25 mg/kg/h; ranitidine-injection: 100 mg/6 h. Results: Omeprazole-infusion versus ranitidine-infusion: on day 1: median pH 6.1 vs 5.1 ( p = 0.01) and 95% vs 70% was pH >4 ( p < 0.01); on day 2: median pH 6.2 vs 3.2 ( p < 0.01); and 100% vs 38% was pH >4 ( p < 0.01); on day 3: median pH 6.3 vs 2.7 ( p < 0.01); 100% vs 26% was pH >4 ( p < 0.01). Injections of both drugs were significantly less effective than the infusions on day 1. Thereafter, omeprazole injection was almost as effective as omeprazole infusion, whereas ranitidine injection and infusion were equally effective. Conclusion: Our study shows, for the first time, that omeprazole infusion was significantly superior to all other regimens by having a high median pH >6 on each day. The tolerance effect of ranitidine, however, led to a rapid loss of antisecretory activity on days 2 and 3, rendering it inappropriate for situations in which high intragastric pH-levels appear to be essential.