Synthesis and anti-inflammatory activity of 5-(1,4-dihydropyridyl)-tetrazol-2-acetic acids, esters and amides.

Thirteen 5-[3-(1,4-dihydropyridyl)]-2H-tetrazol-2-acetic acids (18-30), seventeen esters (4-17, 32, 35, 41) and eight amides (31, 32-34, 36-40) were synthesized in order to investigate the effect of alpha-substituents (R1 = H, Me) and 1,4-dihydropyridyl substituents (R2 = aryl, alkyl; R3 = phenoxy, methoxy or amino) on anti-inflammatory activity. The effects of the R1, R2 or R3-substituents were variable but highly interdependent. The relative order of anti-inflammatory potency was generally acid greater than amide and ester. Methyl 2-methyl-2-(5-[3-(4-phenyl-1-carbamoyl-1,4-dihydropyridyl)]-2H- tetrazol-2-yl) acetate (35) was the most effective anti-inflammatory agent in the group, reducing inflammation 96% at 5 hr after a 50 mg/kg po dose, relative to ibuprofen's 52% inhibition at 5 hr after a 100 mg/kg po dose.