Reversible Inhibitors of the Gastric (H+/K+)-ATPase. 5. Substituted 2,4-Diaminoquinazolines and Thienopyrimidines

Article abstract of DOI:10.1021/jm00014a027

Quinazolines bearing a secondary 4-(arylamino) substituent demonstrate an SAR for inhibition of the gastric (H⁺/K⁺)-ATPase different from the previously described 3-acylquinolines, suggesting that, although these compounds are also K⁺-competitive, they probably bind to the enzyme in a different orientation.Compounds bearing a tertiary 4-(arylamino)substituent, however, in particular 4-(N-methylarylamino), appear to possess an SAR quite similar to the 3-acylquinolines.We show that this arises from the effect of the N-methylation, which is to orientate the 4-(arylamino) substituent syn to C5, analogous to the 3-acylquinolines.Compounds possessing both a 4-(N-methylarylamino) substituent and a 2-(arylamino) substituent proved to be very potent, K⁺-competitive inhibitors of K⁺-stimulated ATPase activity with K_i values down to 12 nM.Some compounds also proved to be effective inhibitors of stimulated acid secretion in both the rat and dog when dosed intravenously.However, although a number of these demonstrated activity after oral administration in the dog, the level and variability precluded further evaluation.