Amidines and related compounds. 6. Studies on structure-activity relationships of antihypertensive and antisecretory agents related to clonidine.

Correlations of antihypertensive and antisecretory activities with various structural modifications of the antihypertensive agent clonidine (2-(2,6-dichlorophenylimino)imidazolidine) are described. Eleven chemical classes of compounds containing an "amidine" moiety were prepared in this study. The antihypertensive activity of these compounds was evaluated in metacorticoid hypertensive rats and unanesthetized neurogenic hypertensive dogs following oral administration. Antisecretory activity was evaluated in fistula rats by measuring pH and volume of gastric secretion. Two compounds, 2-(2,6-dimethylphenylimino)imidazolidine and 2-(2,6-dichlorophenylimino)pyrrolidine, are particularly effective antisecretory agents with minimal antihypertensive activity.