Paradoxical angina after nifedipine: angiographic documentation

Calcium antagonists

Calcium antagonists were introduced for the treatment of hypertension in the 1980s. Their use was subsequently expanded to additional disorders, such as angina pectoris, paroxysmal supraventricular tachycardias, hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension, diffuse esophageal spasms, and migraine. Calcium antagonists as a group are heterogeneous and include 3 main classes--phenylalkylamines, benzothiazepines, and dihydropyridines--that differ in their molecular structure, sites and modes of action, and effects on various other cardiovascular functions. Calcium antagonists lower blood pressure mainly through vasodilation and reduction of peripheral resistance. They maintain blood flow to vital organs, and are safe in patients with renal impairment. Unlike diuretics and beta-blockers, calcium antagonists do not impair glucose metabolism or lipid profile and may even attenuate the development of arteriosclerotic lesions. In long-term follow-up, patients treated with calcium antagonists had development of less overt diabetes mellitus than those who were treated with diuretics and beta-blockers. Moreover, calcium antagonists are able to reduce left ventricular mass and are effective in improving anginal pain. Recent prospective randomized studies attested to the beneficial effects of calcium antagonists in hypertensive patients. In comparison with placebo, calcium antagonist-based therapy reduced major cardiovascular events and cardiovascular death significantly in elderly hypertensive patients and in diabetic patients. In several comparative studies in hypertensive patients, treatment with calcium antagonists was equally effective as treatment with diuretics, beta-blockers, or angiotensin-converting enzyme inhibitors. From these studies, it seems that a calcium antagonist-based regimen is superior to other regimens in preventing stroke, equivalent in preventing ischemic heart disease, and inferior in preventing congestive heart failure. Calcium antagonists are also safe and effective as first-line or add-on therapy in diabetic hypertensive patients. Heart rate-lowering calcium antagonists (verapamil, diltiazem) may have an edge over the dihydropyridines in post-myocardial infarction patients and in diabetic nephropathy. Thus, calcium antagonists may be safely used in the management of hypertension and angina pectoris.

Cardiac effects of calcium antagonists in systemic hypertension

The calcium antagonists are a class of heterogeneous drugs, with a wide spectrum of direct and indirect cardiac effects that vary a great deal from one drug to another and depend upon formulation and duration of action. Calcium antagonists act by decreasing total peripheral resistance to lower arterial pressure. As a consequence, reflex tachycardia, increased cardiac output, and increased plasma catecholamine and plasma renin activity are commonly seen, particularly with the initial dose and with short-acting dihydropyridines. The abrupt vasodilation can paradoxically elicit angina and even acute myocardial infarction. These hemodynamic and neuroendocrine changes are less pronounced with the long-acting formulations. Most calcium antagonists diminish automaticity of the sinus node, slow conduction in the atrioventricular node, and have little, if any, effect on the automaticity of the myocytes. The dihydropyridines generally have less effect on automaticity and cardiac conduction than nondihydropyridines. The negative inotropic effect is most profound with nondihydropyridines and is greatly reduced or absent with newer dihydropyridines, such as isradipine, felodipine, amlodipine, and nisoldipine. Long-acting calcium antagonists generally improve myocardial oxygenation by unloading the heart, increasing coronary blood flow, and reducing myocardial oxygen consumption. Thus, calcium antagonists have a variety of beneficial effects in patients with hypertensive heart disease: they reduce left ventricular hypertrophy and its sequelae, such as ventricular dysrhythmias, impaired filling and contractility, and myocardial ischemia. Ongoing studies should provide a more conclusive answer regarding the efficacy and safety of calcium antagonists.

Comparison of efficacy of nisoldipine, metoprolol, and isosorbide dinitrate in patients with stable exertional angina: a randomized, cross-over, placebo-controlled study

We evaluated the acute antianginal effect of oral nisoldipine (10 mg), metoprolol (40 mg), and long-acting isosorbide dinitrate (20 mg) in 15 patients with stable exertional angina. The patients performed symptom-limited treadmill exercise at 2 h after the administration of placebo (Placebo stages 1 and 2) and each of the active drugs. After Placebo stage 1, the patients were randomized for cross-over evaluation of the acute effect of a single oral dose of placebo (Placebo stage 2), nisoldipine, metoprolol, or long-acting isosorbide dinitrate. All 15 patients developed angina during all of exercise tests and their exercise tests were terminated at the onset of angina. The time until development of 0.1 mV ST segment depression was increased by all three drugs compared to placebo, and it was significantly longer with metoprolol than with isosorbide dinitrate. Similarly, the time to ceasing exercise because of angina was also prolonged by all three drugs. The exercise time was longer with nisoldipine and metoprolol compared to isosorbide dinitrate, but there was no significant difference between nisoldipine and metoprolol. In conclusion, metoprolol and nisoldipine more effectively prolonged exercise compared to long-acting isosorbide dinitrate in patients with stable exertional angina.

Paradoxical effect of long-term treatment of nifedipine on total ischemic load in patients with stable angina pectoris

In 50 patients with stable effort angina the effect of three drugs, metoprolol, nifedipine, and diltiazem was assessed by analyzing exercise stress test response and ambulatory ECG recordings. Both metoprolol and diltiazem caused a significant increase in time to ischemic threshold during exercise and a significant decrease of maximum ST-segment depression (during exercise and ambulatory ECG monitoring) and in the average number of daily ischemic episodes. Only metoprolol significantly reduced heart rate and rate-pressure product at the ischemic threshold during exercise. In the group of patients treated with nifedipine no significant improvement was observed in exercise tolerance or in number of ischemic episodes/24 h. Moreover, the subset of nonresponders in the two methods was larger than in the other two groups. In some of these patients a clearcut worsening of total ischemic load was observed, despite the control of symptoms. This adverse effect might be attributed to the different consequences of the vasodilatory effect of nifedipine on blood flow through stenosed vessels.

Sustained release nifedipine formulations. An appraisal of their current uses and prospective roles in the treatment of hypertension, ischaemic heart disease and peripheral vascular disorders

Nifedipine antagonises influx of calcium through cell membrane slow channels, and sustained release formulations of the calcium channel blocker have been shown to be effective in the treatment of mild to moderate hypertension and both stable and variant angina pectoris. Preliminary findings also indicate that these formulations are effective in the treatment of Raynaud's phenomenon and hypertension in pregnancy, and that they reduce the frequency of ischaemic episodes in some patients with silent myocardial ischaemia. The exact mechanism of action of nifedipine in all of these disorders has not been defined. However, its potent peripheral and coronary arterial dilator properties, together with improvements in oxygen supply/demand, are of particular importance. A major goal of sustained release therapy is to permit reductions in the frequency of nifedipine administration, preferably to once daily, and thus improve patient compliance. Two new once-daily formulations--the nifedipine gastrointestinal therapeutic system (GITS) and a fixed combination capsule comprising sustained release nifedipine 20 mg and atenolol 50 mg--have exhibited marked antihypertensive efficacy. The GITS preparation has also been used effectively in the treatment of stable angina pectoris, and both formulations appear to be well tolerated. Sustained release nifedipine formulations are generally better tolerated than their conventionally formulated counterparts, particularly with regard to reflex tachycardia. Adverse effects seem to be dose related, are mainly associated with the drug's potent vasodilatory action, and include headache, flushing and dizziness. Generally, these effects are mild to moderate in severity and transient, usually diminishing with continued treatment. Thus, sustained release nifedipine formulations are useful and established cardiovascular therapeutic agents which have demonstrable efficacy in various forms of angina, mild to moderate hypertension and Raynaud's phenomenon. Further, promising results shown by the nifedipine GITS formulation, with its advantage of once daily administration suggest that it is likely to become one of the preferred nifedipine formulations for the treatment of hypertension and the various forms of angina.

Cardiovascular characterization of SD-3211, a novel benzothiazine calcium channel blocker, in isolated rabbit hearts

The cardiovascular effects of SD-3211, a novel benzothiazine Ca++ channel blocker, were compared with those of diltiazem and nicardipine in Langendorff-perfused rabbit hearts. SD-3211 was more potent in increasing coronary artery flow than in depressing cardiac function (i.e., contractile force, heart rate and conduction time). The relative specificity of SD-3211 for coronary vasodilation to cardiodepression was clearly greater than that of diltiazem, but less than that of nicardipine. Thus, the present study demonstrates that SD-3211, despite a non-dihydropyridine type of Ca++ channel blocker, can be characterized as a potent coronary vasodilator with a little effect on cardiac function.

Hemodynamic and antianginal effects during rest and exercise of intravenous isradipine, a new dihydropyridine calcium antagonist

In an open randomized study, hemodynamic and antianginal effects of nifedipine and the new dihydropyridine derivative isradipine were compared in patients with stable, angiographically confirmed coronary heart disease. Right heart hemodynamics, systemic arterial blood pressure, ECG, and drug plasma concentrations were measured before medication at rest and exercise, after infusions of increasing doses at rest, and again after treatment at rest and exercise. A linear relationship between serum concentrations and cumulated dosages was obtained for both drugs. At rest, both drugs significantly increased cardiac output and heart rate. The reduction of arterial blood pressure was significantly greater after isradipine (systolic from 148 +/- 3 to 104 +/- 3 mmHg; diastolic from 90 +/- 4 to 58 +/- 2 mmHg) than after nifedipine (systolic 149 +/- 6 to 125 +/- 4 mmHg; diastolic 92 +/- 4 to 76 +/- 3 mmHg). The minimal effective plasma level of isradipine regarding blood pressure reduction was estimated at 5 ng/ml (nifedipine: 10-25 ng/ml). During exercise both medications significantly reduced mean pulmonary artery pressure (isradipine: 40 +/- 3 to 20 +/- 1 mmHg, nifedipine: 37 +/- 4 to 22 +/- 1 mmHg), pulmonary artery wedge pressure (isradipine: 23 +/- 3 to 10 +/- 1 mmHg, nifedipine 24 +/- 3 to 14 +/- 1 mmHg), and diastolic arterial pressure (isradipine: 103 +/- 3 to 73 +/- 4 mmHg, nifedipine: 99 +/- 3 to 91 +/- 2 mmHg), whereas systolic pressure was reduced by only isradipine (189 +/- 4 to 147 +/- 5 mmHg). Neither medication significantly changed electrocardiographic ST depression during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Increase in number of myocardial ischemic episodes following nifedipine administration in two patients. Detection of silent episodes by Holter monitoring and role of heart rate

Out of 34 consecutive patients with angina and treated with nifedipine, two subjects (5.8 percent) showed a significant increase of transient myocardial ischemic episodes during the period of treatment, as assessed by continuous Holter ECG monitoring. In both these patients, a large proportion of ischemic episodes happened to be asymptomatic. A relationship between nifedipine intake, heart rate increase, and number of ischemic episodes was observed. This occasional aggravation of myocardial ischemia could be related to an increase in myocardial oxygen demand medicated through a drug-induced reflex tachycardia.

Different vasomotor action of nifedipine on dynamic coronary obstructions and therapeutic response in effort and prinzmetal angina

Variations induced by nifedipine (10 mg sublingually) in the residual lumen diameter of significant (greater than 50%) coronary lesions were assessed angiographically in 58 patients with effort angina (group 1) and in 19 patients with Prinzmetal angina (group 2). A relationship was sought between these acute variations of the stenotic lumen and the clinical response to treatment with the same drug (20 mg four times daily). Treatment efficacy was evaluated with exercise testing in group 1 and Holter monitoring in group 2. In group 1 the residual segment of stenotic diameter showed an increase, decrease, or no change with the calcium antagonist. Nifedipine failed to improve 40% of the cases (21% unchanged and 19% worsened) in group 1. In the same group of patients, the responses to exercise tests were dissociated from the acute vasomotor pattern. Changes in the pressure-rate product also did not explain the clinical results. In group 2 the majority of lesions had compliant portions, which invariably reacted to nifedipine with dilatation. All patients with the Prinzmetal form had relief of the anginal episodes with treatment. These data suggest that the therapeutic efficacy of nifedipine in classic effort angina probably is the net result of influences on the myocardial oxygen consumption and supply, and the acute coronary vasomotor pattern does not allow to predict the clinical response. Stenotic lesions in the Prinzmetal form possess a distinct sensitivity to the relaxant action of calcium channel blockade, which reasonably explains the highly positive response to treatment.

Comparison of haemodynamic effects of nifedipine and molsidomine in patients with coronary artery disease

The haemodynamic effects of oral nifedipine 20 mg and molsidomine 4 mg were compared in 24 patients with coronary artery disease. Molsidomine unlike nifedipine caused a significant fall in mean pulmonary artery pressure and left ventricular end-diastolic pressure. Both drugs caused a significant and comparable reduction in systolic and diastolic blood pressure. Although only nifedipine significantly reduced systemic vascular resistance the difference between the drugs was not significant. The heart rate was significantly increased by nifedipine but not by molsidomine. The ejection phase indices were all increased by molsidomine and the increment in the mean normalized systolic ejection rate was significantly greater than that due to nifedipine. The left ventricular end-systolic volume index decreased significantly after molsidomine but not nifedipine. Neither drug significantly affected left ventricular end diastolic volume index, stroke volume index, maximal rate of rise of left ventricular pressure or left ventricular stroke work index.

Unstable angina with tachycardia: clinical and therapeutic implications

We prospectively evaluated 19 patients with prolonged chest pain not evolving to myocardial infarction and accompanied with reversible ST-T changes and tachycardia (heart rate greater than 100 beats/min) in order to correlate heart rate reduction with ischemic electrocardiographic (ECG) changes. Fourteen patients (74%) received previous long-term combined treatment with nifedipine and nitrates. Continuous ECG monitoring was carried out until heart rate reduction and at least one of the following occurred: (1) relief of pain or (2) resolution of ischemic ECG changes. the study protocol consisted of carotid massage in three patients (16%), intravenous propranolol in seven patients (37%), slow intravenous amiodarone infusion in two patients (10%), and intravenous verapamil in four patients (21%) with atrial fibrillation. In three patients (16%) we observed a spontaneous heart rate reduction on admission. Patients responded with heart rate reduction from a mean of 125 +/- 10.4 beats/min to 84 +/- 7.5 beats/min (p less than 0.005) and an ST segment shift of 4.3 +/- 2.13 mm to 0.89 +/- 0.74 mm (p less than 0.005) within a mean interval of 13.2 +/- 12.7 minutes. Fifteen (79%) had complete response and the other four (21%) had partial relief of pain. A significant direct correlation was observed for heart rate reduction and ST segment deviation (depression or elevation) (r = 0.7527 and 0.8739, respectively). These patients represent a unique subgroup of unstable angina, in which the mechanism responsible for ischemia is excessive increase in heart rate. Conventional vasodilator therapy may be deleterious, and heart rate reduction in mandatory.

Coronary vasomotor and clinical effects of nifedipine in effort, mixed and Prinzmental angina

Changes induced by nifedipine (10 mg s.l.) in the residual lumen diameter of significant (greater than 50%) coronary lesions were assessed angiographically in 69 patients with effort angina (Group 1), in 22 patients with mixed angina (Group 2), and in 14 patients with Prinzmental angina (Group 3). These changes were related to the clinical response to treatment with the same drug (diary records, exercise testing, Holter monitoring). In Groups 1 and 2 segments of stenotic vessels showed either increase, decrease or no change in diameter with the calcium antagonist; in Group 3 the majority of the vessels showed compliant portions which invariably responded with dilatation. Nifedipine failed to improve cases with exertional (21% unchanged, 19% worsened) and mixed (41% exacerbated) forms; all patients with the Prinzmental form had relief of the anginal episodes. In Group 1, the response to exercise tests were dissociated from the acute vasomotor pattern and the pressure-rate product failed to explain the clinical results. Fifty-two percent of the patients in Group 2 showed significant acute widening of critical stenoses as well as obvious improvement; patients in this group who did worse with treatment had reacted to nifedipine with narrowing of their critical stenoses. These data suggest that: the response to nifedipine of classic effort angina is probably the net result of an interaction of changes in myocardial oxygen consumption and supply; coronary vasomotion has a role in mixed angina and influences of nifedipine may be either favorable or unfavorable; stenotic lesions in the Prinzmental form are quite sensitive to the relaxant action of calcium blockade and this probably represents a background to the highly positive clinical response to treatment.

Preload or afterload reduction: which is more beneficial for patients with ischemic heart disease?

We studied the acute hemodynamic effects of molsidomine, a selective preload reducing agent, and nifedipine, a selective afterload reducing agent. Thirty-two patients with stable angina pectoris and angiographically significant coronary artery disease were randomized into two groups: group A patients received 4 mg of molsidomine, and group B patients received 20 mg of nifedipine orally. Molsidomine was associated with a significant reduction of the left ventricular end-diastolic pressure and an increase in Vcf. Nifedipine caused a significant reduction of the mean arterial pressure and an increase of the heart rate. Hemodynamic parameters associated with chronic exertional angina pectoris in patients with angiographically significant coronary artery disease improved more with a preload reducing agent, like molsidomine.

Diltiazem, nifedipine, and their combination in patients with stable angina pectoris: effects on angina, exercise tolerance, and the ambulatory electrocardiographic ST segment

The efficacy and safety of oral nifedipine and diltiazem were compared in 20 patients with stable angina pectoris with use of a placebo run-in, randomized, double-blind titration to maximal effect crossover protocol. The effects of treatment withdrawal were also analyzed. All patients received placebo for 2 weeks and were then randomly assigned to receive either diltiazem or nifedipine. A 2 week drug titration phase in which patients received either diltiazem (180 to 360 mg/day) or nifedipine (30 to 120 mg/day) in three divided doses was followed by a 1 week maintenance phase. Patients then received placebo for 1 to 2 weeks, followed by crossover to the other treatment regimen and a second placebo washout period of 1 week. Patients (n = 13) who remained symptomatic on both diltiazem and nifedipine during the monotherapy periods entered a 3 week combination treatment phase, followed by a final 1 week placebo washout period. Frequency of angina, nitroglycerin consumption, exercise tolerance (Naughton protocol), and frequency of daily episodes of ST segment deviations on the electrocardiogram (1 mm of ST segment depression persisting for at least 1 min with and without chest pain) on an ambulatory electrocardiographic monitor were assessed during the baseline placebo, active monotherapy, placebo withdrawal, and combination treatment phases. Plasma drug levels were also measured. Compared with initial placebo values, the frequency of angina and the amount of nitroglycerin treatment were reduced by both diltiazem (p less than .001) and nifedipine (p less than .02). Diltiazem was more effective than nifedipine in reducing angina (p less than .02). Exercise duration increased with both drugs (p less than .0001). Diltiazem was significantly better than nifedipine in reducing the episodes of ST segment depression on the ambulatory monitor (p less than .01). Diltiazem reduced the resting heart rate (p less than .01); both drugs reduced the resting blood pressure and rate-pressure product. Overall, combination therapy was more effective in patients who did not maximally respond to diltiazem or nifedipine alone with respect to anginal and exercise variables and in reducing blood pressure at rest and during exercise. Plasma drug levels could not predict an individual patient's treatment response. Diltiazem may increase nifedipine drug levels when the drugs are combined. Fewer side effects were observed with diltiazem than nifedipine; the most side effects were seen with combination treatment. There were no apparent withdrawal effects observed with either treatment regimen.(ABSTRACT TRUNCATED AT 400 WORDS)

Nifedipine and angina pectoris. Short-term changes in quantitative coronary angiography with nifedipine and clinical response to treatment in effort-induced, mixed, and spontaneous angina pectoris

Changes induced by nifedipine (10 mg sublingually) in the residual luminal diameter of significant (greater than 50 percent) coronary lesions were assessed angiographically in 69 patients with effort-induced angina (group 1), in 22 patients with mixed angina (group 2), and in 14 patients with Prinzmetal's angina (group 3). These changes were related to the clinical response to treatment with the same drug, as evaluated through diary records and Holter monitoring in the mixed (spontaneous component) and Prinzmetal forms and through exercise testing in effort-induced and mixed (effort-associated component) angina. In groups 1 and 2, segments of stenotic vessels showed either an increase or decrease or no change in diameter with the calcium antagonist; in group 3, the majority of the lesions had compliant portions which invariably responded with dilatation. Nifedipine failed to improve cases with exertional (20 percent [14/69] unchanged; 19 percent [13/69] worsened) and mixed (41 percent [9/22] exacerbated) forms; 100 percent of the 14 patients with the Prinzmetal form had relief of the anginal episodes. In group 1, the response to exercise tests was dissociated from the short-term vasomotor pattern, and the pressure-rate product failed to explain the clinical results. Forty-five percent (ten) of the patients in group 2 showed significant short-term widening of critical stenoses, as well as obvious improvement; patients who did worse with treatment in this group had reacted to nifedipine with narrowing of critical stenoses. These data suggest that the response to nifedipine of classic effort-induced angina is probably the net result of an interaction of changes in myocardial oxygen consumption and supply; coronary vasomotion has a role in mixed angina, and influences of nifedipine may be either favorable or unfavorable; stenotic lesions in the Prinzmetal form are quite sensitive to the relaxant action of calcium blockade, and this probably represents a background to the highly positive clinical response to treatment.

Nifedipine, its action on the cationic concentrations in heart, vessels, skeletal muscle and blood in tissues of normotensive and spontaneously hypertensive rats (SHR)

1. The cationic tissue distribution, obtained by atomic absorption spectrophotometry, was different in normotensive (Wistar) and spontaneously hypertensive male rats (SHR). 2. In both groups, nifedipine (4.2 mg/100 g body wt, by gastric intubation, during 10 days) altered the cationic composition mainly in the aorta, atria and in SHR also in the vein. 3. In normotensive Wistar rats (NWR), nifedipine provoked a higher concentration of divalent cations (Ca2+, Mg2+ and Zn2+) in the ascending part of the aorta and reduced the monovalent (Na+) concentration in the aorta, vein and skeletal muscle. 4. In spontaneously hypertensive rats (SHR) the pathognomonic higher cationic concentrations in the aorta, right atrium and vein are significantly (P less than 0.05) reduced after nifedipine treatment.

Comparative antianginal effects of nisoldipine and nifedipine in patients with chronic stable angina

The acute antianginal effects of 5 mg and 20 mg nisoldipine were compared with 20 mg nifedipine and placebo. Maximal treadmill exercise testing was performed before and 3 hours after drug administration in 10 patients with chronic stable angina. Resting heart rate and systolic blood pressure were unchanged following low-dose nisoldipine, but 20 mg nisoldipine and 20 mg nifedipine increased heart rate and decreased systolic arterial pressure (p less than 0.05). Time (in seconds) to the onset of 0.1 mV ST segment depression was significantly prolonged after 5 mg nisoldipine (+60 +/- 53; p less than 0.05) and 20 mg nisoldipine (+100 +/- 78; p less than 0.01) but not after 20 mg nifedipine (+48 +/- 131; p = NS). Total exercise duration increased significantly following 5 mg and 20 mg nisoldipine (p less than 0.01 and p less than 0.001, respectively) but only slightly following nifedipine (p = NS). The maximal rate-pressure product was increased to a similar degree following doses of both nisoldipine and nifedipine (p less than 0.05). Nisoldipine is an effective antianginal agent which performs well in comparison to nifedipine.

Nicardipine for angina pectoris at rest and coronary arterial spasm

The antiischemic effects and safety of nicardipine were assessed in 17 patients with angina at rest and coronary arterial spasm in a randomized placebo-controlled study over 8 to 13 weeks. Eleven patients had previously had unsatisfactory results with long-acting nitrates or other calcium blockers. The average daily dosage of nicardipine for optimal angina relief was 89 mg (range 40 to 160). During the double-blind phase, angina frequency decreased with nicardipine compared with placebo (mean 0.47 vs 2.11 attacks/day, p less than 0.05). A similar decrease in nitroglycerin requirements occurred (0.51 vs 2.77 tablets/day, p less than 0.05). During placebo periods, 51 episodes of ischemic ST-segment shifts occurred during 482 hours of ambulatory electrocardiographic monitoring and 12 (24%) were associated with angina. During nicardipine treatment, only 15 episodes of ST-segment shifts occurred during 498 hours of monitoring. In 1 patient a burning skin rash developed; otherwise, the drug was generally well tolerated. Thus, nicardipine is effective and safe in preventing symptomatic and asymptomatic ischemia in patients with coronary spasm. It may be particularly beneficial in patients with unsatisfactory responses to other therapy.

Coronary hemodynamic and metabolic effects of nifedipine in patients with coronary artery disease treated with beta-blocking drugs

In humans, reflex sympathetic nerve activation modulates the direct cardiac action of nifedipine after systemic administration and results in a positive chronotropic and inotropic response. The coronary hemodynamic and metabolic effects of nifedipine were evaluated after propranolol-induced acute beta-receptor blockade in 12 patients with angiographically documented coronary artery disease. The intravenous injection of propranolol led to a decrease in heart rate, coronary blood flow and myocardial oxygen consumption and an increase in coronary vascular resistance and the coronary arteriovenous oxygen difference. Mean aortic pressure did not change. The subsequent intravenous administration of nifedipine resulted in a transient increase in coronary blood flow and a reduction in coronary vascular resistance and the coronary arteriovenous oxygen difference and a sustained decrease in mean aortic pressure and myocardial oxygen consumption without significant changes in heart rate. Thus, in the presence of beta-receptor blockade, the positive chronotropic response to nifedipine is attenuated and nifedipine reduces myocardial oxygen consumption significantly. The vasodilatory effect of nifedipine is maintained and a potential propranolol-related inappropriate vasoconstriction may be reversed. The combination of nifedipine and beta-receptor blocking agents may be useful in the treatment of patients with both effort-induced angina and angina related to changes in coronary vasomotor tone.

Prevention of vasospastic angina with nicardipine

Anti-ischaemic effects and safety of nicardipine were assessed in 14 patients with vasospastic angina using a placebo comparison, cross-over design study for 8-13 weeks. The average daily dose of nicardipine for optimal angina prevention was 84 mg (range 40-160 mg). Nicardipine administration, as compared with placebo, significantly reduced anginal frequency and nitroglycerin consumption during the single- and double-blind phases of the study. Nicardipine appears to be effective in the prevention of vasospastic angina and not to cause major adverse effects.