Effects of pumaprazole (BY841), a novel reversible proton pump antagonist, and of omeprazole, on intragastric acidity before and after cure of Helicobacter pylori infection

Abstract

Omeprazole produces a higher intragastric pH in the presence of Helicobacter pylori infection than after cure. To investigate whether this effect also occurs with pumaprazole (BY841), a reversible proton pump antagonist which, in contrast to omeprazole, does not require activation in the acid compartment of the parietal cell. In a randomized, crossover, double-blind study, 24-h intragastric pH was measured in 13 H. pylori-positive subjects before and after a 1-week course of omeprazole (20 mg o.d.) or of pumaprazole (100 mg b.d.). The studies were repeated after the infection was cured. In the absence of drug administration, the median 24-h pH values before cure (median 2.0, 90% CI: 1.2–3.2) did not differ from those after cure (median 1.5, 90% CI: 1.3–2.2; P = 0.115). The 24-h pH values were higher before cure of the infection than after during both pumaprazole (6.0, 4.8–6.7 vs. 4.3, 2.6–5.7; P = 0.002) and omeprazole (5.8, 4.0–6.2 vs. 3.6, 2.8–5; P = 0.004). Both before and after cure, there were no significant differences between the two drugs with respect to acid inhibition over the 24-h period. The median decrease in acid inhibition after cure of the infection (calculated as the difference in H⁺ activity in mmol/L) during pumaprazole (median 0.05, 90% CI: 6 × 10^–4– 2.3) was no different from that during omeprazole (median 0.2, 90% CI: 3 × 10^–3–1.5; P = 0.6). Both before and after cure of H. pylori infection, pumaprazole raised the intragastric pH over a 24-h period to a similar degree as omeprazole. H. pylori infection similarly augments the pH-increasing effect of both drugs. This effect is related to H. pylori infection and not to an increased activation of acid inhibitory agents in the parietal cell compartment.