IC50: 3.1±0.4 μM (H ⁺ /K ⁺ -ATPase)

Picoprazole inhibits the H ⁺ /K ⁺ -ATPase activity in a concentration-dependent manner. The IC ₅₀ value is 3.1±0.4 μM. Picoprazole is a specific inhibitor of H ⁺ /K ⁺ -ATPase and binds to 100-kDa polypeptides of the enzyme, dose dependently inhibited opening of the Cl ^- conductance by Cu ²⁺ -o-phenanthroline, indicating that the Cl ^- conductance is part of the function of the H ⁺ /K ⁺ -ATPase. The inhibitory effect of the three benzimidazole derivatives Timoprazole, Picoprazole, and Omeprazole on histamine and dbcAMP stimulated ¹⁴ C-aminopyrine accumulation (H ⁺ secretion) has been studied in isolated and enriched guinea-pig parietal cells. All compounds tested inhibit H ⁺ secretion in a concentration dependent manner with IC ₅₀ values of 8.5±1.9 μM for Timoprazole, 3.9±0.7 μM for Picoprazole, and 0.13±0.03 μM for Omeprazole.