The combination of chlorthalidone with nifedipine does not exert an additive antihypertensive effect in essential hypertensives: a crossover multicenter study.

To evaluate whether the combination of nifedipine with chlorthalidone exerts an additive antihypertensive effect when compared to single-drug treatment, 66 uncomplicated essential hypertensives, whose diastolic blood pressure was greater than 100 and less than 115 mm Hg at the end of a 1-month washout placebo period, received, according to a randomized, double-blind, crossover design, nifedipine (20 mg b.i.d.), chlorthalidone (25 mg o.d.), the two drugs combined at the same doses, and the corresponding placebo. When compared to the randomized placebo the three active treatments significantly (p less than 0.001) reduced blood pressure without changing heart rate and body weight. However, blood pressure values were similarly reduced under nifedipine and the combination and were significantly lower (p less than 0.05) than those under chlorthalidone. Moreover, the percentage of responders and normalized patients under nifedipine and the two drugs combined were similar and significantly (normalized, p less than 0.0001; responders, p less than 0.02) greater than those under chlorthalidone. Under chlorthalidone and its combination with nifedipine, plasma potassium tended to decrease and blood glucose and serum uric acid were significantly (p less than 0.05) increased. These data show that the combination of nifedipine with chlorthalidone does not exert any additive antihypertensive effect when compared to nifedipine alone and that this combination increases both blood glucose and serum uric acid. Taken together these findings indicate that the combination of a dihydropyridine calcium antagonist with a thiazide diuretic is devoid of any clinical significance in the treatment of uncomplicated essential hypertensives.

Chlorthalidone does not increase the hypotensive effect of nifedipine in essential hypertensives: a crossover multicentre study.

To determine whether the combination of nifedipine + chlorthalidone exerts an additive antihypertensive effect when compared with single-drug treatment, we studied 66 uncomplicated essential hypertensives, with diastolic blood pressure of greater than 100 and less than 115 mmHg. At the end of a 1-month washout placebo period, using a double-blind crossover design, the patients were randomly allocated to nifedipine (20 mg twice a day), chlorthalidone (25 mg once a day), the two drugs combined at the same doses and the corresponding placebo. Compared with the randomly allocated placebo, the three active treatments significantly reduced blood pressure without changing the heart rate or body weight. Both the absolute and percentage decreases in mean blood pressure induced by nifedipine and the combination compared with placebo were similar and significantly greater than those induced by chlorthalidone. Taken together, these data show that the combination of nifedipine + chlorthalidone does not exert any additive antihypertensive effect compared with nifedipine alone. This finding indicates that the combination of a dihydropyridine calcium antagonist + a thiazide diuretic is probably devoid of any particular clinical significance in the treatment of uncomplicated essential hypertensives.