WY-26769

WY‐26,769 (2‐3‐dihydro‐2‐(2‐pyridinyl) thiazolo‐[3,2‐a]benzimidazole) is a gastric antisecretory agent that acts by inhibiting the parietal cell proton pump. In vitro, WY‐26,769 was active against dbcAMP‐stimulated aminopyrine uptake in isolated parietal cells. Preincubating the drug with liver microsomal enzymes increased its potency 50 times, to an IC50 of 6.8 μM. Wy‐26,769 and its oxidative metabolite Wy‐26,876 each inhibited the H+/K+ ATPase (IC50 = 42 μM and 18 μM, respectively). In whole animal studies, Wy‐26,769 inhibited histaminestimulated gastric acid secretion (ID50 = 3 mg/kg) irrespective of whether Wy‐26,769 was administered orally or intravenously. Wy‐26,769 was not degraded in acid and also inhibited gastric acid secretion in the pylorus‐ligated rat. Wy‐26,769 was equiactive after oral or intravenous administration demonstrating that it is an acid stable proton pump inhibitor.