Monotherapy of stable angina with nicardipine hydrochloride: double-blind, placebo-controlled, randomized study

A randomized, double-blind comparison of lercanidipine 10 and 20 mg in patients with stable effort angina: clinical evaluation of cardiac function by ambulatory ventricular scintigraphic monitoring

We evaluated the antiischemic action and the effects on left ventricular response to exercise of lercanidipine, a long-acting dihydropyridine calcium antagonist, in 23 patients with stable effort angina in a randomized, double-blind, parallel trial. Left ventricular function was assessed during upright bicycle exercise using an ambulatory radionuclide detector for continuous noninvasive monitoring of cardiac function. Exercise was performed under control conditions before (run-in placebo period) and after 2-week treatment with lercanidipine 10 or 20 mg once daily. During the placebo run-in period and at the study end, patients underwent clinical examination, ECG, exercise tests, ambulatory ventricular scintigraphic monitoring (VEST). Results showed that both drug doses increased time to onset of ST segment depression >/=1 mm and peak ST segment depression, with improvement of total exercise duration. Heart rate, blood pressure, and the rate-pressure product did not significantly change with respect to pretreatment value. The left ventricular ejection fraction, indicating contractility state of myocardium, was unchanged at rest and during exercise after both lercanidipine doses. In conclusion, lercanidipine is safe and effective in reducing ischemia in patients with stable effort angina without any deterioration of cardiac function.

Vanidipinedilol: a vanilloid-based beta-adrenoceptor blocker displaying calcium entry blocking and vasorelaxant activities

Calcium channel and beta-adrenoceptor blockade have proved highly useful in antihypertensive therapy. Studies of the mechanisms of action of vanidipinedilol that combine these effects within a single molecule are described here. Intravenous injection of vanidipinedilol (0.1, 0.25, 0.5, 1.0, and 2.0 mg/kg) produced dose-dependent hypotensive and bradycardic responses, significantly different from nifedipine-induced (0.5 mg/kg, i.v.) hypotensive and reflex tachycardic effects in pentobarbital-anesthetized Wistar rats. A single oral administration of vanidipinedilol at doses of 10, 25, and 50 mg/kg dose-dependently reduced blood pressure with a decrease in heart rate in conscious spontaneously hypertensive rats (SHRs). In the isolated Wistar rat atrium, vanidipinedilol (10(-7), 10(-6), and 10(-5) M) competitively antagonized the (-)isoproterenol-induced positive chronotropic and inotropic effects and inhibited the increase in heart rate induced by Ca2+ (3.0-9.0 mM) in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)isoproterenol and CaCl2 suggested that vanidipinedilol possessed beta-adrenoceptor-blocking and calcium entry-blocking activities. On tracheal strips of reserpinized guinea pig, cumulative doses of vanidipinedilol (10(-10) to 3x10(-6) M) produced dose-dependent relaxant responses. Preincubating the preparation with ICI 118,551 (10(-10), 10(-9), 10(-8) M), a beta2-adrenoceptor antagonist, shifted the vanidipinedilol concentration-relaxation curve significantly to a region of higher concentrations. These results implied that vanidipinedilol had a partial beta2-agonist activity. In the isolated thoracic aorta of rat, vanidipinedilol had a potent effect inhibiting high-K+-induced contractions. KCI-induced intracellular calcium changes of blood vessel smooth muscle cell (A7r5 cell lines) determined by laser cytometry also was decreased after administration of vanidipinedilol (10(-8), 10(-7), 10(-6) M). Furthermore, the binding characteristics of vanidipinedilol and various antagonists were evaluated in [3H]CGP-12177 binding to ventricle and lung and [3H]nitrendipine binding to cerebral cortex membranes in rats. The order of potency of beta1- and beta2-adrenoceptor antagonist activity against [3H]CGP-12177 binding was (-)propranolol (pKi, 8.59 for beta1 and 8.09 for beta2) > vanidipinedilol (pKi, 7.09 for beta1 and 6.64 for beta2) > atenolol (pKi, 6.58 for beta1 and 5.12 for beta2). The order of potency of calcium channel antagonist activity against [3H]nitrendipine binding was nifedipine (pKi, 9.36) > vanidipinedilol (pKi, 8.07). The ratio of beta1-adrenergic-blocking/calcium entry-blocking selectivity is 0.1 and indicated that vanidipinedilol revealed more in calcium entry-blocking than in beta-adrenergic-blocking activities. It has been suggested that vanidipinedilol-induced smooth muscle relaxation may involve decreased entry of Ca2+ and partial beta2-agonist activities. In conclusion, vanidipinedilol is a nonselective beta-adrenoceptor antagonist with calcium channel blocking and partial beta2-agonist associated vasorelaxant and tracheal relaxant activities. Particularly, the vasodilator effects of vanidipinedilol are attributed to a synergism of its calcium entry blocking and partial beta2-agonist activities in the blood vessel. A sustained bradycardic effect results from beta-adrenoceptor blocking and calcium entry blocking, which blunts the sympathetic activation-associated reflex tachycardia in the heart.

Clinical implications of the World Health Organization-International Society of Hypertension statement on calcium antagonists

The controversy over the efficacy and safety of calcium antagonists is over 2 years old. Since millions of patients worldwide are currently using calcium antagonists for the treatment of high blood pressure and angina, a systematic review of their potential risks and benefits is much needed. In response to this need, the World Health Organization (WHO) and the International Society of Hypertension (ISH) recently convened an ad-hoc subcommittee to review the available evidence (J Hypertens 1997, 15:105-115). Importantly, the WHO-ISH statement does take a strong stand in favor of large long-term trials that compare antihypertensive agents, and we all agree that these comparative trials are urgently needed. However, the WHO-ISH statement is marred in part by errors of omission, by the selective use of evidence and epidemiologic principles, and by a narrow application of the viewpoint of those who believe that evidence can come only from the results of megatrials. As a result, practicing clinicians will find more useful information in existing hypertension and postmyocardial infarction guidelines (Arch Intern Med 1993, 153:154-183 and JAm Coll Cardiol 1996, 28:1328-1428).

Cardiovascular effects of elgodipine and nifedipine compared in anaesthetized rats

The cardiovascular effects of elgodipine were studied and compared with those of nifedipine in the presence or absence of ganglion blockade. A bolus of elgodipine (5-25 microg/kg) or nifedipine (60-120 microg/kg) was given and sequential cardiovascular effects in rats were recorded. Both dihydropyridines induced a dose-dependent decrease in mean arterial pressure but, whereas nifedipine induced reflex tachycardia, elgodipine induced a dose-dependent bradycardia. Both substances induced decreases in left ventricular d P/dt(max) without significant changes in central venous pressure. Good linear correlation was observed between the elgodipine-induced decrease in mean arterial pressure and those of heart rate and left ventricular dP/dt(max). The profile of the decrease in mean arterial pressure in animals pretreated with hexametonium chloride (20 mg/kg) was the same but the nifedipine-induced tachycardia was abolished without changes in elgodipine-induced bradycardia. These characteristics of elgodipine makes this dihydropyridine a potentially beneficial therapeutic agent in the case of severe hypertension accompanied by obstructive coronopathy.

Calcium antagonists in the elderly. A risk-benefit analysis

Calcium antagonists are effective in lowering blood pressure, relieving anginal symptoms and improving exercise tolerance in older and younger patients with coronary artery disease. Verapamil and diltiazem are effective in slowing ventricular response rates to supraventricular arrhythmias in both older and younger patients. Although they belong to at least 3 distinct chemical classes, a moderate decrease in the clearance of all calcium antagonists occurs with aging. Most clinical trials of these drugs have used the same dosages in older and younger patients, confounding analyses of sensitivity in older compared with younger patients. Greater reductions in blood pressure usually occur in older compared with younger patients receiving the same dosages of calcium antagonists; similarly, the dosage required to reduce blood pressure to a certain level is usually lower in older compared with younger patients. Drug acquisition costs are generally higher for calcium antagonists than for beta-blockers or diuretics. Compared with younger patients, greater heart rate suppression may be seen in older patients treated with verapamil and diltiazem; conversely, heart rate increases are usually seen with dihydropyridines. Calcium antagonists have not been shown to provide long-term benefits or decreased morbidity or mortality in elderly patients with hypertension. Verapamil, but not dihydropyridines, decreases mortality after myocardial infarction in patients without congestive heart failure. Calcium antagonists have not been shown to be beneficial in the treatment of acute stroke. Adverse effects, such as a postural hypotension, may be more frequent in elderly compared with younger patients. In addition, the elderly are at greater risk for drug interactions with calcium antagonists due to the higher likelihood that they are receiving other drugs.

Nifedipine. Dose-related increase in mortality in patients with coronary heart disease

BACKGROUND

The purpose of this study was to assess the effect of the dose of nifedipine, a dihydropyridine calcium antagonist, on the increased risk of mortality seen in the randomized secondary-prevention trials and to review the mechanisms by which this adverse effect might occur.

METHODS AND RESULTS

We restricted the dose-response meta-analysis to the 16 randomized secondary-prevention trials of nifedipine for which mortality data were available. Recent trials of any calcium antagonist and formulation were also reviewed for information about the possible mechanisms of action that might increase mortality. Overall, the use of nifedipine was associated with a significant adverse effect on total mortality (risk ratio, 1.16, with a 95% CI of 1.01 to 1.33). This summary estimate fails to draw attention to an important dose-response relationship. For daily doses of 30 to 50, 60, and 80 mg, the risk ratios for total mortality were 1.06 (95% CI, 0.89 to 1.27), 1.18 (95% CI, 0.93 to 1.50), and 2.83 (95% CI, 1.35 to 5.93), respectively. In a formal test of dose response, the high doses of nifedipine were significantly associated with increased mortality (P = .01). While the mechanism of this adverse effect is not known, there are several plausible explanations, including the established proischemic effect, negative inotropic effects, marked hypotension, recently reported prohemorrhagic effects attributed to antiplatelet and vasodilatory actions of calcium antagonists, and possibly proarrhythmic effects.

CONCLUSIONS

In patients with coronary disease, the use of short-acting nifedipine in moderate to high doses causes an increase in total mortality. Other calcium antagonists may have similar adverse effects, in particular those of the dihydropyridine type. Long-term safety data are lacking for most calcium antagonists.

Comparison of the haemodynamic profiles of elgodipine and nicardipine in the anaesthetized dog

1. The haemodynamic profile of elgodipine (1-30 micrograms kg-1, i.v.), a new dihydropyridine calcium antagonist, has been compared directly with that of nicardipine (1-30 micrograms kg-1, i.v.) in chloralose-anaesthetized dogs. 2. Nicardipine produced dose-related systemic, pulmonary and coronary vasodilatation accompanied by reflex tachycardia, inotropy and increases in cardiac output and myocardial oxygen consumption (MVO2). Elgodipine had similar vasodilator and hypotensive properties to nicardipine but produced less reflex inotropy, little or no reflex tachycardia and did not increase MVO2. 3. Both calcium antagonists were retested in a separate group of anaesthetized dogs pretreated with propranolol (1 mg kg-1, i.v.) and atropine (0.3 mg kg-1, i.v.) to abolish reflex autonomic tone to the heart and thus reveal the direct cardiac effects of each compound. Under these conditions both elgodipine and nicardipine decreased heart rate and cardiac contractility and slowed atrio-ventricular conduction. Elgodipine was approximately ten times more potent than nicardipine as a decelerator agent and slightly more potent in depressing cardiac contractility and increasing PR interval duration. Elgodipine, unlike nicardipine, slightly reduced the QTc interval of the electrocardiogram. Therefore, the potent decelerator effect of elgodipine, which was present throughout the dose-range, appears to be largely responsible for the suppression of reflex tachycardia observed when the baroreflex is functional. 4. Elgodipine is a potent systemic and coronary vasodilator with more marked direct cardiac effects than nicardipine, particularly with respect to slowing of heart rate. The ability of elgodipine to increase coronary blood flow without significant reflex tachycardia or increases in MVO2 suggests that this compound will have a more favourable effect on myocardial oxygen supply/demand balance than nicardipine. The haemodynamic profile of elgodipine may be suitable for the treatment of angina.

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.