1. Prizidilol (SKF 92 657), a new antihypertensive drug with combined precapillary vasodilator and non-selective β-adrenoceptor-blocking actions, was given to 24 patients with essential hypertension in a placebo-controlled, dose-titration study, Incremental doses from 200 to 800 mg were given once daily. Supine and standing blood pressure measured 24–27 h after drug intake was reduced during treatment with prizidilol (400–800 mg/day). Slight but significant decreases in heart rate were seen after moderate doses (mean: 447 mg once daily) of prizidilol. A more pronounced blood pressure reduction was noticed 2–7 h after drug administration.
2. Maximal blood pressure reduction coincided with peak plasma concentration of prizidilol, which was measured by a newly developed assay.
3. Plasma renin activity and 24 h urinary excretion of aldosterone and methoxycatecholamines were reduced after the highest doses (mean: 700 mg once daily) of prizidilol.
4. Prizidilol was well tolerated, although dizziness and tiredness were reported by four patients and oedema by two.