The antihypertensive efficacy of the new dihydro-pyridine derivative nilvadipine given once daily was compared in two randomized, double-blind studies with that of hydrochlorothiazide/triamterene (HCT/T) and of enalapril. In the first study, arterial pressures were compared after 4 weeks of therapy with nilvadipine (16 mg q.d.) or HCT/T (25/50 mg q.d.) in patients with mild-to-moderate hypertension in a parallel-group design. The combination of both treatments was administered after 4 weeks if diastolic arterial pressures were <90 mm Hg. The blood pressure (BP) in the nilvadipine group (n = 125) was 161/102 ± 17/7 (mean ± SD) mm Hg after a 2-week placebo period and decreased after 4 weeks by – 16/– 13 ± 22/12 mm Hg. The BP decreased in the HCT/T group (n = 124) compared to the nilvadipine group to a similar degree (p = 0.91, n.s.) from 160/103 ± 17/8 mm Hg by −17/-13 ± 18/11 mm Hg. A combination therapy was started after 4 weeks in 39 patients in the nilvadipine group and in 34 patients in the HCT/T group. This led independently of the treatment sequence, to a similar decrease in BP in the nilvadipine group (– 17/7 ± 16/10 mm Hg) and in the HCT/T group (-12/9 ± 16/9 mm Hg). In the second study, the antihypertensive effect of nilvadipine (1 x 8 mg) was compared with that of enalapril (1x10 mg) in a randomized, double-blind, crossover design. Sixty-one patients with essential hypertension (WHO I–II) were treated over two 4-week periods following placebo periods of 2 weeks. Nonresponders (BP <90 mm Hg) were subsequently treated for an additional 4 weeks with a combination of both drugs given at the same dosage. The BP decreased to a similar degree after 4 weeks on nilvadipine from 175/108 ± 13/7 mm Hg by −19/-13 mm Hg and from 176/107 ± 13/6 mm Hg by −21/-13 mm Hg after 4 weeks on enalapril to 156/95 + 14/ 9 mm Hg and 155/94 ± 16/10 mm Hg, respectively. Goal diastolic BPs <90 mm Hg were not achieved with monotherapy in 27 patients, but 15 of these 27 patients responded favorably to a combination of nilvadipine and enalapril with diastolic BPs <90 mm Hg. Combination therapy caused a decrease in the diastolic BP of −14/-13 mm Hg. In conclusion, nilvadipine administered once daily was as effective as hydrochlorothiazide or enalapril in lowering the BP. In combination with a diuretic, the sequence of treatments, i.e., diuretic first or nilvadipine first, had no influence on antihypertensive efficacy. The combination of calcium antagonist and diuretic was as effective as that of the calcium antagonist with enalapril.
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