1. The antihypertensive effect of 4 weeks' treatment with prizidilol (SKF 92657) (mean dosage 520 mg once or twice daily) was studied in ten essential hypertensive patients.
2. Both systolic and diastolic blood pressure were significantly reduced in all cases. Supine heart rate did not change, and in the erect position heart rate was significantly lowered.
3. Blood pressure reduction was due to peripheral vasodilatation, as the cardiac index increased after 4 weeks of prizidilol treatment.
4. After prizidilol plasma noradrenaline and adrenaline increased significantly, and PRA and plasma aldosterone were reduced. Although plasma volume increased, body weight did not change.
5. Cardiac performance, as evaluated by the PEP/LVET ratio, improved after treatment with prizidilol.