Studies on nonpeptide angiotensin II receptor antagonists. I. Synthesis and biological evaluation of pyrazolo[1,5-b][1,2,4]triazole derivatives with alkyl substituents.

Alkyl-substituted pyrazolo[1,5-b][1,2,4]triazole derivatives were synthesized and evaluated for activity as angiotensin II receptor antagonists. Molecules with the (methylbiphenylyl)tetrazole moiety and N-5 were the preferred compounds. Ethyl substitutions at both C-2 and C-7 resulted in the optimal compound, 2,7-diethyl-5-[[2"-(1H -tetrazol-5-yl)biphenyl-4-yl]methyl]-5H-pyrazolo[1,5-b][1,2,4]tria zole (5n), with a pA2 value of 8.774 in rabbit aorta. In the in vivo tests, 5n inhibited the angiotensin II-induced pressor response in rats after oral administration. This compound also produced a dose-dependent decrease in blood pressure when administered orally to conscious furosemide-treated dogs, having a longer duration of action as compared to DuP753. These data suggest that 5a may be a useful agent for the treatment of angiotensin II-dependent disease, such as hypertension.