The
antihypertensive, biochemical and adverse effects of
captopril,
hydralazine,
nifedipine and placebo were compared in 160 patients with BP inadequately controlled by
atenolol 100 mg daily plus
bendrofluazide 5 mg daily. Treatments were given for up to 12 weeks. Beta-blocker and
thiazide were continued unchanged. All three active drugs reduced supine BP relative to placebo; mean BP changes attributable to active treatment (95% confidence intervals):
captopril 13.4/10.3 mmHg (0.6/4.0 to 26.2/16.6),
hydralazine 15.0/10.0 mmHg (1.7/3.4 to 28.3/16.6),
nifedipine 16.8/8.1 mmHg (4.0/1.8 to 29.6/14.4). There were no significant differences between the agents. Results for erect BP were similar. Target BP (< 140/95 mmHg) was achieved more frequently on
captopril (33%),
hydralazine (29%) and
nifedipine (17%) than on placebo (10%). Compared with the other treatments
captopril increased serum
potassium concentration (P = 0.01), and
hydralazine reduced serum
cholesterol concentration (median changes:
captopril -0.2 mmol/l,
hydralazine -0.8 mmol/l,
nifedipine -0.2 mmol/l, and placebo +0.2 mmol/l, P < 0.001). Overall, side-effects did not differ significantly between the groups; withdrawals resulting from adverse reactions:
captopril 15%,
hydralazine 24%,
nifedipine 22%, and placebo 3% (chi 2 = 8.2, P = 0.04).
Captopril,
hydralazine and
nifedipine did not differ significantly in efficacy and tolerability when added to
atenolol and
bendrofluazide. However, there were trends in favour of
captopril, on which
drug the highest proportion of patients had their BP controlled and the lowest proportion were withdrawn because of side-effects. Thus, of the drugs tested,
captopril appears to be the best option as third
drug in
hypertension.