EFFICACY OF CAPTOPRIL AND NIFEDIPINE IN BLACK-AND-WHITE PATIENTS WITHHYPERTENSIVE CRISIS

We examined the antihypertensive efficacy of: (1) sublingual-oral sing le doses of captopril (25 mg) and nifedipine-capsules (10 mg) in 9 + 9 white patients and in 9 + 8 black patients with hypertensive crisis; and (2) a single oral dose of the slow-acting preparation of nifedipin e-retard (20 mg) in another 10 black patients. Blood pressure (BP) was assessed at 10 min intervals for 6 h after administration. After 6 h, the BP falls induced by these drugs were still significantly lower th an the baseline placebo values. Hypotensive effect of nifedipine-capsu les was established more rapidly than that of captopril in both white and black patients, and of nifedipine-retard in black patients. Consid ering the area under the curve of BP values during the 6-h treatment, the overall hypotensive effect of nifedipine-capsules was similar to c aptopril in white patients, but significantly more pronounced than cap topril and nifedipine-retard in black patients. In white patients simi lar maximal drops of BP (mean +/- s.e.m.) were obtained with nifedipin e-capsules (71 +/- 4/52 +/- 4 mm Hg) and with captopril (69 +/- 4/50 /- 3 mm Hg). In black patients the maximal drop of BP of nifedipine-ca psules (70 +/- 4/52 +/- 4 mm Hg) was greater (P < 0.02) than that of c aptopril (48 +/- 4/32 +/- 3 mm Hg) but similar to that of nifedipine-r etard (71 +/- 4/49 +/- 4 mmHg). However, in contrast to nifedipine-cap sules and captopril, nifedipine-retard produced a slower drop in BP. T he time of peak drop in BP of both nifedipine-capsules and captopril o ccurred within the first 2h whereas with nifedipine-retard it occurred only between 4 and 6 h after administration. Fewer patients reported side effects with nifedipine-retard as compared with the other two pre parations. We conclude that single doses of captopril and nifedipine r educes BP for at least 6 h in both white and black patients with hyper tensive crisis, but nifedipine is more potent than captopril in black patients. The slow release form of nifedipine-retard effectively and s afely lowers BP while achieving a rapid enough effect without the crit ical rapid falls in BP that occur with nifedipine-capsules.