A comparison of nine calcium ion antagonists and propranolol: exercise tolerance, heart rate and ST-segment changes in patients with chronic stable angina pectoris

Withdrawal of prenylamine: perspectives on pharmacological, clinical and regulatory outcomes following the first QT-related casualty

Prenylamine, an antianginal agent marketed since early 1960, became the first casualty of QT interval related proarrhythmias in 1988 when it was withdrawn from the market. The period of its synthesis and marketing is of particular interest since it antedated, first, any serious clinical safety concern regarding drug-induced prolongation of the QT interval which was, in fact, believed to be an efficient antiarrhythmic mechanism; second, the first description of torsade de pointes as a unique proarrhythmia, typically associated with prolonged QT interval; and third, the discovery and recognition of calcium antagonism as an important cardiovascular therapeutic strategy. This review, 30 years almost to the day following its withdrawal, provides interesting perspectives on clinical, pharmacological and regulatory outcomes that followed. Prenylamine underscored torsadogenic potential of other early antianginal drugs on the market at that time and identified QT-related proarrhythmias as a much wider major public health issue of clinical and regulatory concern. This resulted in various guidelines for early identification of this potentially fatal risk. Application of these guidelines would have readily identified its proarrhythmic potential. Prenylamine also emphasized differences in drug responses between men and women which subsequently galvanized extensive research into sex-related differences in pharmacology. More importantly, however, investigations into the mechanisms of its action paved the way to developing modern safe and effective calcium antagonists that are so widely used today in cardiovascular pharmacotherapy.

Efficacy and safety of fasudil in patients with stable angina: a double-blind, placebo-controlled, phase 2 trial

OBJECTIVES

This study sought to evaluate the efficacy and safety of fasudil, an orally available rho kinase inhibitor, in patients with stable angina.

BACKGROUND

Several small, non-placebo-controlled trials suggest that fasudil reduces myocardial ischemia in patients with stable or vasospastic angina.

METHODS

In a multicenter, double-blind, placebo-controlled, randomized trial, the efficacy and safety of fasudil were evaluated in stable angina patients. Of the 206 patients screened, 84 patients with reproducible exercise times were randomized 1:1 to fasudil or placebo. Nitroglycerin as needed and a beta- or calcium-channel blocker were allowed. Fasudil or matching placebo was force-titrated from 20 mg three times daily to 80 mg twice daily with 20 mg twice-daily increments every two weeks. Symptom-limited exercise testing was performed after two, four, six, and eight weeks of treatment.

RESULTS

At peak, exercise duration was significantly improved at all visits in both groups, although exercise duration was numerically greater in patients receiving fasudil versus those receiving placebo. Time to > or =1 mm ST-segment depression was increased with fasudil at both peak and trough compared with placebo (172.1 s vs. 44.0 s, p = 0.001, and 92.8 s vs. 26.4 s, p = 0.02, respectively). Fasudil improved Seattle Angina Questionnaire scores. No significant differences in Canadian Cardiovascular Society class, time to angina, or frequency of angina or nitroglycerin use were noted between groups. Fasudil did not affect heart rate or blood pressure, and was well tolerated.

CONCLUSIONS

Fasudil up to 80 mg three times daily significantly increased the ischemic threshold of angina patients during exercise with a trend toward increased exercise duration. Further investigation of fasudil doses >80 mg three times daily is indicated.

Hemodynamic effects of intravenous elgodipine in coronary artery disease during rest and exercise, and basic pharmacokinetic parameters

Using an echo-Doppler method (Quantascope), the hemodynamic profile of the calcium channel antagonist elgodipine (64 micrograms/kg, i.v.) was investigated in 22 patients with angina pectoris at rest and during exercise. A placebo control was used. At rest, elgodipine significantly decreased systemic vascular resistance as well as systolic and diastolic blood pressure, while increasing cardiac output and stroke volume. During supine bicycle exercise the constant workload, elgodipine significantly increased cardiac output and stroke volume, and decrease the rate-pressure-product (double product); the exercise systolic blood pressure was decreased without change in the diastolic component. Elgodipine significantly reduced the incidence and severity (self-rated pain score) of exercise-induced anginal systems. Heart rate was not affected by elgodipine, either at rest or during exercise. In particular, no negative inotropy could be inferred from the echo-Doppler data. In the elgodipine plasma concentration profile (HPLC), three phases of elimination with half-life times of less than 1 hour, between 3 and 7 hours, and between 10 and 24 hours may be distinguished, indicating a "shallow" and a "deep" compartment. The hemodynamic data indicate an intermediate pharmacodynamic profile of elgodipine, lying between that of other dihydropyridines and that od compounds such as verapamil or diltiazem.

Gallopamil. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in ischaemic heart disease

Gallopamil is a methoxy derivative of verapamil. As is typical of the phenylalkylamine class of calcium antagonists, it acts on the vascular system, and on the heart and its nodal structures. In the treatment of stable angina pectoris, gallopamil is at least as effective as nifedipine and diltiazem, though apparently better tolerated than nifedipine. Typical of calcium antagonists there is little or no tolerance to the antiischaemic effects of gallopamil. Preliminary studies indicate that gallopamil, like other calcium antagonists, has cardioprotective potential. However, further investigation is required to explore the clinical relevance of the improved myocardial regional perfusion and free fatty acid utilisation in reversibly ischaemic regions, and the potential of delayed ischaemia during angioplasty that is observed during gallopamil administration. Gallopamil is well tolerated, exhibiting a low propensity for causing cardiovascular and gastrointestinal adverse effects, thus making it a suitable alternative to other calcium antagonists for the treatment of patients with ischaemic heart disease.

Atenolol or nicardipine alone is as efficacious in stable angina as their combination: a double blind randomised trial

BACKGROUND

Beta blockers and calcium antagonists are widely used in the management of angina pectoris in the belief that the combination is more efficacious than either drug alone.

METHODS

This double blind randomised crossover placebo controlled study compares the effects of nicardipine, atenolol and their combination in 30 patients with chronic stable angina. Each treatment period lasted 6 weeks with dose titration after 3 weeks. Symptom limited treadmill exercise testing and radionuclide ventriculography at rest was carried out at the end of each treatment period.

RESULTS

Total exercise duration and time to 1-mm ST-segment depression was significantly prolonged by nicardipine and atenolol when compared to placebo, the combination offered no additional benefit. Time to onset of angina was significantly prolonged by nicardipine and the combination but not by atenolol. Indices of left ventricular function were not significantly affected by any treatment other than an increase in left ventricular end diastolic volume on atenolol and the combination.

CONCLUSIONS

Nicardipine and atenolol are equally effective in prolonging exercise duration and time to onset of ischemia in patients with chronic stable angina while the combination appeared to offer no additional benefit. Nicardipine prolonged the time to onset of angina significantly; again there was no further improvement with the combination. Neither drug appears to have an important effect on the parameters of diastolic function studied in patients with chronic stable angina.

Effects of atenolol and diltiazem on exercise tolerance and ambulatory ischaemia

Twenty-five normotensive patients with stable angina, angiographically documented coronary disease and normal left ventricular function were randomized to a crossover study comparing atenolol 100 mg x 1, sustained-release diltiazem 120 mg x 2, and their combination. A maximal symptom limited bicycle exercise test and a 24-h ambulatory electrocardiographic (ECG) monitoring were performed at the end of each treatment period. Exercise duration was increased equally in the different treatment groups. Time to onset of 1-mm ST-segment depression was longer with atenolol (P < 0.02) and combination therapy (P < 0.01) than with diltiazem. The maximal ST-segment depression was decreased with atenolol (P < 0.05) and combination therapy (P < 0.02), whereas, time to onset of angina was prolonged only with combination therapy (P < 0.03). The number of ischaemic episodes during ambulatory monitoring was lower with atenolol and combination therapy than with diltiazem (P < 0.01). The difference between atenolol and diltiazem was mainly due to lower ischaemic activity with atenolol between 06:00 h and 12:00 h (P < 0.05). Anginal frequency (P < 0.01) and nitroglycerin consumption (P < 0.05) were lower with combination therapy than with monotherapy. Thus, while comparable effects were achieved on clinical variables, atenolol appeared to be more effective than diltiazem, reducing myocardial ischaemia during exercise and ambulatory monitoring. With combination therapy, both clinical and electrocardiograph signs of ischaemia were improved.

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.

Effects of benazepril and metoprolol OROS alone and in combination on myocardial ischemia in patients with chronic stable angina

The efficacy of benazepril, metoprolol OROS and their combination was evaluated in 29 patients (42 to 74 years of age) with chronic stable angina and documented coronary artery disease in a placebo-controlled, double-blind, crossover trial using serial quantitated exercise testing and ambulatory electrocardiographic (ECG) monitoring. The mean (+/- SEM) exercise time was 8.5 +/- 0.7 min with placebo, 8.3 +/- 0.6 min (95% confidence interval [CI]-1.06 to 0.54) with benazepril, 9.4 +/- 0.5 min (95% CI -0.32 to 2.14) with metoprolol OROS and 9.6 +/- 0.5 min (95% CI -0.25 to 2.47) with the combination of benazepril and metoprolol OROS. The mean exercise time to the development of 1 mm ST segment depression was prolonged from 6.0 +/- 0.6 min with placebo to 6.3 +/- 0.6 min (95% CI -0.93 to 1.45) with benazepril, 7.9 +/- 0.5 min (95% CI 0.83 to 3.0) with metoprolol OROS and 8.1 +/- 0.6 min (95% CI 0.88 to 3.29) with the combination of benazepril and metoprolol OROS. Benazepril did not alter the rest or maximal heart rate, whereas metoprolol OROS alone and in combination significantly lowered the heart rate at rest and during maximal exercise. Systolic blood pressure at rest was nonsignificantly reduced, whereas diastolic blood pressure was lowered significantly by all treatments in comparison with placebo. At maximal exercise, only metoprolol OROS, whether given alone or in combination with benazepril, was able to blunt significantly systolic blood pressure and rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)

Stable angina pectoris: 3. Medical treatment

The therapeutic goals for the patient with angina pectoris are to minimize the frequency and severity of angina and to improve functional capacity at a reasonable cost and with as few side effects as possible. An integrated approach necessitates attention to conditions that might be aggravating angina, such as anemia or hypertension. Alterations in life-style and personal habits, such as cessation of cigarette smoking, are often necessary and should be continually reinforced by the physician. Certain concomitant diseases, such as chronic obstructive pulmonary disease, may influence the selection of drug therapy. Nitrates, beta-adrenergic blockers, and calcium entry blockers are the major classes of drugs that can be used alone or in combination in a program that is designed for the individual patient.

Calcium-channel blockers in acute myocardial infarction

The calcium-channel blockers are useful in treating a variety of cardiovascular disorders. Due to their antiischemic and spasmolytic properties, these agents have been studied in the prophylaxis and treatment of acute myocardial infarction. This article reviews this application with respect to reduction of mortality, infarct size, and reinfarction rate. Of the agents currently available for clinical use, nifedipine has been studied most extensively. This agent shows no beneficial effects in this setting and its use may in fact be harmful. Of the few trials that have been conducted with verapamil, none have shown decreased mortality. Verapamil may reduce infarct size although further confirmation is required. Diltiazem is the only agent that has been shown to have short- and long-term benefits in the patient with acute myocardial infarction. Proper patient selection is of utmost importance in ensuring successful therapy. In particular, those patients with non-Q-wave infarctions and/or normal left ventricular function can be expected to derive the most benefit in terms of reducing mortality and reinfarction rate associated with the acute event.

Nicardipine, a new calcium channel blocker: role for vascular selectivity

Calcium channel blockers are important drugs for the treatment of chronic stable angina. However, negative inotropic and dromotropic effects may limit their usefulness in patients with atrioventricular conduction abnormalities or left ventricular dysfunction. A new generation of calcium channel blockers will soon be available that have a more vascular selective action than currently available agents. Of the new agents, nicardipine has been most extensively studied. In experimental studies, nicardipine is more specific for vascular smooth muscle than for cardiac smooth muscle and for coronary than peripheral vasculature. In controlled trials, nicardipine exhibited efficacy and safety that was comparable to older calcium blockers or beta blockers. However, nicardipine was associated with minimal negative inotropic or dromotropic effects even in patients with existing left ventricular dysfunction. Thus, nicardipine may have an advantage over existing calcium channel blockers, especially in patients with underlying cardiac disease.

Calcium channel antagonists. Part II: Use and comparative properties of the three prototypical calcium antagonists in ischemic heart disease, including recommendations based on an analysis of 41 trials

An analysis of 41 trials of angina of all varieties confirms that calcium antagonists are an important advance and are now established therapy for these syndromes. In effort angina, verapamil in a dose of 360-480 mg daily is better than propranolol in standard doses. Although nifedipine is highly effective against vasospastic angina, its use in threatened myocardial infarction or severe unstable angina is not supported by recent studies, unless combined with a beta-blocker. Diltiazem has recently been tested with apparent benefit in non-Q-wave myocardial infarction. Otherwise, these calcium antagonist agents all seem to have approximate equipotency in clinical ischemic syndromes including effort and vasospastic angina. Subjective side effects seem most troublesome in the case of nifedipine. All three calcium antagonists, especially nifedipine, have been successfully combined with beta-blocker therapy, yet occasional additive negative inotropic or chronotropic or dromotropic interactions may occur when verapamil or diltiazem is added to beta-blockade, and occasionally the direct negative inotropic potential of nifedipine may become evident. The choice between the calcium antagonists is determined not only by the clinical picture but also by the anticipated side effects in a given patient and by the overall cardiovascular status. In patients with supraventricular tachycardias or sinus tachycardia, verapamil or diltiazem is preferred, whereas in patients with a resting bradycardia or borderline heart failure nifedipine is likely to be chosen.