SK&F 92657, a novel antihypertensive acting by precapillary vasodilatation and beta-adrenoreceptor blockade.

1. The properties of a new antihypertensive agent, SK&F 92657, DL-3-[2-(3-t-butylamino-2-hydroxypropoxy)phenyl]-6-hydrazinopyridazine, have been studied. 2. The compound caused a sustained fall in blood pressure in several species as a result of precapillary vasodilatation, particularly in the renal and coronary vasculatures. 3. The beta-adrenoreceptor-blocking actions of SK&F 92657 prevent reflex cadiac stimulation.