Carvedilol, a novel beta-blocker with a vasodilating action, was given either alone (monotherapy) or with diuretics (combination therapy) to 42 patients with renal hypertension. The hypotensive effect, safety, and optimal dose were investigated. In all, 23 untreated patients (16 men and 7 women; average age, 56.4 +/- 2.5 years) made up the monotherapy group and 19 diuretic-treated patients (11 men and 8 women; average age, 56.4 +/- 2.5 years) comprised the combined therapy group. All subjects had an initial blood pressure (BP) of greater than 160/95 mmHg and were started on 5 mg/day oral carvedilol. The dose was gradually increased to a maximum of 20 mg/day, or until either the BP was reduced to less than 149/89 mmHg or the reduction in mean BP was greater than 13 mmHg compared with baseline levels. The total study period was 8 weeks. With monotherapy, the BP and heart rate decreased significantly from 167/102 to 150/94 mmHg and from 81 to 74 beats/min, respectively. With combined therapy, the BP and heart rate fell significantly from 176/103 to 142/85 mmHg and from 81 to 70 beats/min, respectively. Responders were defined as subjects with a BP of less than or equal to 149/89 mmHg or those showing a fall of greater than or equal to 13 mmHg in mean BP. Responders accounted for 52.2% of the monotherapy group and 73.6% of the combination therapy group. Orthostatic hypotension was not seen in either group. Serum creatinine and blood urea nitrogen (BUN) levels were not altered by administration of carvedilol. Dizziness was noted by 1 of the 23 subjects in the monotherapy group.(ABSTRACT TRUNCATED AT 250 WORDS)