1. The antihypertensive effect of the new drug, SKF 92 657, a hydrazinopyridazine derivative, possessing both β-adrenoreceptor-blocking and vasodilating properties, was investigated in essential hypertension.
2. Single oral doses of 1.0 or 2.0 mg/kg did not produce any consistent decrease in blood pressure; 4.0 mg/kg was the threshold dose for a mild but not significant blood pressure reduction, whereas 8.0 mg/kg caused a significant and marked blood pressure decrease without clinically relevant changes in heart rate.
3. Continued administration of the drug for 7 days induced a significant and uniform reduction in blood pressure without tachycardia. The increase in systolic blood pressure and in heart rate caused by dynamic exercise was left unaffected by the drug.