Double-blind, dose-response, placebo-controlled multicenter study of nisoldipine. A new second-generation calcium channel blocker in angina pectoris

BACKGROUND

Nisoldipine is a potent 1:4 dihydropyridine calcium channel antagonist, and doses of 5 or 10 mg administered either once or twice daily have been claimed to exert antianginal effects. There is, however, little information regarding the dose-response relation and whether the drug exerts any consistent effects throughout the dosing interval. In this placebo-controlled, parallel-design study, the dose-response relation of monotherapy with nisoldipine administered twice daily was studied in patients with stable angina pectoris.

METHODS AND RESULTS

Two hundred thirty-one patients received single-blind placebo for 2 weeks; of these, 185 patients who reproducibly stopped treadmill exercise because of angina of moderate severity and had greater than or equal to 1 mm ST segment depression during exercise and experienced an average of three episodes of anginal attacks per week were randomized in a double-blind manner to one of the four treatment groups: placebo (n = 48), nisoldipine 2.5 mg (n = 47), nisoldipine 5 mg (n = 44), or nisoldipine 10 mg (n = 46). Nisoldipine or placebo was administered twice daily for 4 weeks and symptom-limited exercise tests were repeated at 2 and 10-14 hours after the double-blind medication. One hundred sixty-eight patients completed the study and 181 patients were valid for efficacy analysis. Compared with double-blind placebo, there were marginally significant trends toward increases for time to onset of angina for the 10-mg-b.i.d. group (83 versus 108 seconds, p = 0.08), time to 1 mm ST segment depression for the 5-mg-b.i.d. group (54 versus 83 seconds, p = 0.08), and total exercise time for the 5- (30 versus 50 seconds, p = 0.10) and 10-mg-b.i.d. (30 versus 58 seconds, p = 0.06) groups at 2 hours after the dose (peak effect) after 4 weeks of therapy. At 10-14 hours after the dose (trough effect), no differences between placebo and any of the nisoldipine doses on any of the exercise parameters were found after 4 weeks of therapy. A subset analysis of patients who stopped exercise within 10 minutes because of angina of moderate severity during single-blind placebo therapy (n = 123) revealed significant increase in total exercise duration and time to 1 mm ST segment depression at 2 hours after the dose in the 5- and 10-mg-b.i.d. dose groups compared with double-blind placebo (p less than 0.04). No significant trough effects, however, were observed even in this subgroup after any of the doses of nisoldipine. The frequency of anginal attacks decreased by 44%, 41%, 30%, and 41% after twice-daily therapy with 2.5 mg, 5 mg, 10 mg nisoldipine, and placebo groups, respectively (p = NS, nisoldipine versus placebo). The incidence of adverse events (minor and major) was 43.8% in the placebo group and 42.6%, 45.5%, and 56.5% in the nisoldipine 2.5-, 5-, and 10-mg-b.i.d. groups, respectively (p = NS compared with placebo). However, four patients developed unstable angina while on nisoldipine therapy (two in the 2.5-mg, one in the 5-mg, and one in the 10-mg-b.i.d. group) and two patients died suddenly in the nisoldipine 10-mg-b.i.d. group.

CONCLUSIONS

Monotherapy with 2.5, 5, and 10 mg nisoldipine twice a day was not superior to placebo therapy in treating patients with angina pectoris, and the 10-mg-b.i.d. therapy resulted in a statistically insignificant but clinically important increase in the incidence of serious adverse events.

Influence of calcium antagonists on renal function and secondary hyperparathyroidism in acute renal failure in rats

Glycerol-induced acute renal failure (ARF) is characterized by an increase in serum creatinine, urea, and phosphate concentration, and severe impairment of creatinine clearance. Secondary hyperparathyroidism develops rapidly during ARF. The calcium antagonist nisoldipine clearly improves renal function, which becomes evident by an improvement of creatinine clearance and attenuation of the increase of serum creatinine, urea, and phosphate concentrations. Further secondary hyperparathyroidism is ameliorated by nisoldipine treatment. In spite of normalization of the hypocalcemia in ARF by nisoldipine, weak hyperparathyroidism persists, suggesting that hypocalcemia is not exclusively responsible for elevated parathyroid hormone serum levels in ARF.

[Calcium antagonists in heart failure?]

Although beneficial acute hemodynamic effects of calcium antagonists in heart failure have been reported, their use in this setting is still controversial because of the negative inotropic effects produced by these agents. The direct actions of calcium antagonists, that is direct depression of myocardial contractility and coronary and peripheral vasodilation, are modulated by systemic hypotension-induced baroreceptor activation of autonomic reflexes. Thus, at clinically relevant dosages, the baroreceptor-mediated cardiac stimulatory effects may counterbalance or override the direct negative-inotropic effects, as usually observed with nifedipine or diltiazem. By contrast, with verapamil significant depression of contractility may occur. Newer calcium antagonists with higher vasoselectivity such as nisoldipine or felodipine may be particularly interesting in the setting of congestive heart failure because of pronounced arterial vasodilatation and their additional effects on coronary blood flow, LV-regional wall motion and diastolic function and peripheral blood flow distribution with negligible myocardial effects. Due to their marked vasodilatating properties, newer derivatives may be advantageous in the treatment of heart failure due to coronary artery disease and hypertension. Although limited data concerning long-term efficacy are available, preliminary studies suggest long-term benefit in selected patients. It appears that verapamil should not be used for vasodilator therapy of severe heart failure, since deterioration of LV function may occur.