The present invention is directed to new 4,7-dihydro-pyrazolo[3,4-b]pyridines. The compounds possess Ca.sup.2+ -antagonist, antihypertensive, vasodilating and antiangina activity. A process for producing them as well as pharmaceutical compositions containing them are also described.
A series of 4-aryl-4, 7-dihydropyrazolo [3, 4-b] pyridine-5-carboxylate derivatives (72-149) was prepared and the compounds were tested for Ca-blocking activity in isolated guinea pig portal vein, antihypertensive activity in spontaneously hypertensive rats, and coronary vasodilating effect in isolated guinea pig heart. A number of derivatives had potent antihypertensive and coronary vasodilating activities. The structure-activity relationships of the series indicated that a 3-cyclopentyl or 3-cyclohexyl substituent and a hydrophobic 5-ester moiety with moderate bulkiness were effective for increasing the pharmacological potencies.