Dose-response relationship of prizidilol hydrochloride (SK&F 92657): a comparison between acute and chronic effects in patients with essential hypertension.

Three different doses (50, 100 and 200 mg) of prizidilol hydrochloride (SK&F 92657), a novel antihypertensive agent with vasodilating and beta-adrenoreceptor blocking properties, were given to three (n = 5) groups of essential hypertensive patients in order to evaluate hypotensive dose-response relationship of the drug and its beta-adrenoreceptor blocking properties. Irrespective of the dose given, acute administration of prizidilol did not effectively decrease blood pressure; however after one-week of treatment prizidilol was effective in reducing blood pressure at both the 100 and the 200 mg b.i.d. schedules. At these doses the drug decreased resting heart rate and plasma renin activity for the first 4-6 h after both acute and steady-state dosing. Similarly postdynamic exercise tachycardia was reduced to a significant extent by the drug; after acute administration this effect lasted 2 h with the lowest dose and 4 h with the highest one. After chronic administration this effect lasted up to 10 h for both the 100 and 200 mg doses. These data indicate that: chronic prizidilol treatment can achieve a satisfactory control of blood pressure in patients with mild-moderate essential hypertension; when prizidilol is administered chronically in hypertensive patients, an equally effective control of blood pressure can be obtained with either a 200 mg b.i.d. or a 100 mg b.i.d. schedule; prizidilol possesses beta-adrenoceptor blocking properties in man which can contribute to its pharmacodynamic activity.