Pildralazine is a hydralazinelike antihypertensive vasodilator containing a free hydrazine group. Potency of the compound was shown to be from 6 to 10 times greater than that of hydralazine although, from a qualitative point of view, the two drugs act similarly. Pildralazine was shown to be inactive on nictitating membrane contractions induced by sympathetic stimulation or by adrenaline injection into the lingual artery. However, it antagonized the vascular effects of adrenaline, angiotensin and vasopressin in pithed rats and spinal cats. Pildralazine significantly inhibited the onset of severe hypertension in rats; the combination of pildralazine with moderately effective doses of propranolol or dihydrochlorothiazide completely prevented the blood pressure increase. Whereas a lack of carcinogenic activity has been reported for pildralazine in 1983, a report published in Germany in 1985 states the drug to be mutagenic with auxotrophic mutants of S.Typhimurium and E.coli.