Efficacy and safety of incremental doses of diltiazem for the treatment of stable angina pectoris

Reduction of resting heart rate with antianginal drugs: review and meta-analysis

The benefit of heart rate (HR) reduction in patients with stable coronary artery disease is well demonstrated for symptom prevention and relief, and benefits on outcomes are being actively investigated. We aimed to quantify the reduction in resting HR induced by 5 antianginal drugs frequently used for symptom prevention (diltiazem, verapamil, atenolol, metoprolol, and ivabradine) in stable angina pectoris. We identified studies published between 1966 and 2007 in PubMed, Embase, and the Cochrane database and reviewed the bibliographies to locate additional studies. Eligible studies were double-blind, randomized, placebo-controlled trials in patients with stable angina. Trials were combined using weighted mean difference and fixed-effect model meta-analysis. The main outcome measure was resting HR at the study end. For diltiazem, resting HR reduction versus placebo ranged from -0.08 beats per minute (bpm) [95% confidence interval (CI) -1.5 to +1.4] for 120 mg/d to -8.0 bpm (95% CI, -11.1 to -5.0) with 360 mg/d. For sustained-release diltiazem, there was a reduction in resting HR of -4.5 bpm (95% CI, -6.4 to -2.5), with no dose-response relationship (heterogeneity P = 0.62). Resting HR reductions for the other agents were -3.2 bpm (95% CI, -5.1 to -1.3) for verapamil (with no dose-response relationship, heterogeneity P = 0.87); -19.0 bpm (95% CI, -20.4 to -17.6) for atenolol; -13.2 bpm (95% CI, -14.7 to -11.7) for metoprolol (with greater reductions for 150 mg/d and long-acting 190 mg/d); and between -9.3 bpm (95% CI, -13.8 to -4.8) and -19.6 bpm (95% CI, -23.8 to -15.4) for ivabradine. Ivabradine, atenolol, and metoprolol give similar reductions in resting HR (-10 to -20 bpm), whereas verapamil and diltiazem produce only marginal reductions (<10 bpm).

Effectiveness of diltiazem for chronic stable angina pectoris

Diltiazem can be effective monotherapy for most patients with chronic stable angina pectoris. The exact mechanism(s) of action of diltiazem for producing a salutary effect in patients with angina pectoris is unknown, but probably involves a reduction in myocardial oxygen demand and an increase in supply via coronary artery dilatation. Administration of less than or equal to 240 mg/day in divided doses uncommonly produces any side effects. Doses of 360 mg/day may be required in some patients. The major adverse effect of high dose therapy is mild pedal oedema. Caution concerning orthostatic hypotension is advised when high dose diltiazem is combined with nitrate therapy or used in patients with poor left ventricular function. Also, diltiazem may potentiate bradycardia or atrio-ventricular block, especially when combined with digitalis preparations or beta-blockers. However, in patients with severe angina, diltiazem may be additive to nitrate and/or beta-blocker therapy.

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.

Anomalies in the dosing of diltiazem

From early research, investigators understood that the dose of diltiazem required for the treatment of hypertension (commonly 360 mg/day) was greater than that required for the treatment of angina (commonly 240 mg/day). Nonetheless, studies of recent prescribing practices show that the 240 and 180 mg capsule strengths constitute more than 70% of the diltiazem prescriptions for hypertension. Physicians became accustomed to the lower antianginal doses of diltiazem for 7 years before a hypertension indication was approved. Subsequently, these dosing levels were reinforced by the production of once-a-day formulations with highest capsule strengths of 240 mg and 300 mg. These strengths were dictated by the sheer bulk of the formulations, which limited how much diltiazem could be inserted into the #00 capsule, the largest capsule that can be comfortably administered. An examination of the combined data from the six randomized, blinded, and placebo-controlled trials submitted to the FDA for the original new drug applications of the three formulations of diltiazem available in the United States shows a clear linear dose-response relationship between diltiazem dose and blood pressure lowering through the 480-540 mg/day range. It also demonstrates that the 90-120 mg/day range is the "no-effect dose." These conclusions are supported by a MEDLINE review of all other studies of multilevel dosing of higher dose levels of diltiazem. The data support the conclusion that diltiazem is generally underdosed, but when properly dosed may be the single most potent antihypertensive overall.

Three-month efficacy and safety of once-daily diltiazem in chronic stable angina pectoris

The 3-month efficacy and safety of a once-daily controlled formulation of diltiazem (180 to 360 mg/day) were assessed in a study of 54 patients with angina pectoris. This multicenter study was a nonrandomized, placebo run-in, open-label, 3-month trial followed by a 1-week, double-blind, randomized period during which most patients (89%) received placebo. There were only minimal changes in the time to termination (mean change +/- SEM -5.8 +/- 9.6 seconds), time to onset of angina (10.5 +/- 12.2 seconds), and the time to 1 mm ST-segment depression (2.9 +/- 12.5 seconds) from the end of the titration phase to the end of the open-label study. There were, however, statistically significant differences between the end of the 3-month treatment phase and the end of the 1-week randomized placebo phase for those 3 efficacy parameters (-37.3 +/- 11.2, -58.6 +/- 13.6, and -45.6 +/- 16.4 seconds, respectively). Diltiazem significantly decreased the frequency of anginal attacks and nitroglycerin use at the end of the 3-month treatment phase compared with results at the end of the randomized double-blind placebo phase. No new or unusual adverse events were reported during treatment. The present results suggest that there is no loss of efficacy of once-a-day diltiazem when administered for a long period to patients with chronic stable angina pectoris.

Dose-ranging study of a new, once-daily diltiazem formulation for patients with stable angina

A double-blind safety and efficacy dose-ranging study was conducted with a new, once-daily, extended-release (XR) diltiazem hydrochloride formulation (Dilacor XR, Rhône-Poulenc Rorer, Collegeville, PA) in 189 patients with chronic stable angina pectoris. After a 2-week placebo lead-in phase, the patients were randomly assigned to 1 of 4 once-daily, fixed-dose treatment groups: placebo, XR diltiazem 120 mg, 240 mg, or 480 mg. Extended-release diltiazem, at 240-mg and 480-mg once-daily doses, significantly improved (P < .05) total exercise time during treadmill exercise tolerance testing after 2 weeks of treatment when assessed 24 hours after the previous dose. These increasing doses of XR diltiazem were associated with incremental improvements in exercise tolerance. Outpatient function, as assessed by frequency of anginal attacks, nitroglycerin use, and ambulatory electrocardiogram (Holter, Scole Engineering Culver City, CA) monitoring of ischemic events, was also improved by XR diltiazem. This extended-release diltiazem formulation can be clinically titrated within the 120- to 480-mg dosing range, permitting effective once-daily administration for treating chronic stable angina.

Dose-response evaluation of once-daily therapy with a new formulation of diltiazem for stable angina pectoris. Diltiazem CD Study Group

Diltiazem hydrochloride in a once-daily capsule formulation (DCD) has recently been approved in the United States for the treatment of mild to moderate hypertension and chronic stable angina pectoris. This trial evaluated the dose response of DCD in patients with chronic stable angina pectoris. In a multicenter, randomized, double-blind, parallel-design trial, the effects and tolerability of once-daily therapy with placebo or DCD (60, 120, 240, 360, or 480 mg) were evaluated 24 hours after dosing, following 3 weeks of therapy in 227 patients with reproducible stable exertional angina pectoris. A significant linear dose trend (p = 0.004) was present across the 6 treatment groups for the primary end point--time to exercise termination at 24 hours after dosing--using a standard Bruce treadmill exercise test. A significant linear dose trend was also seen for time to 1 mm ST-segment depression at 24 hours after dosing. Similar effects on exercise parameters were also seen at 4 hours after dosing. A linear dose trend (p = 0.04) was noted relative to the overall anginal attacks during daily activities and for anginal attacks during exercise (p = 0.02). Overall frequency of treatment-related adverse effects was dose-related and occurred in 24.4% and 17.5% of patients treated with DCD and placebo, respectively. At a dose up to 240 mg/day, improvement in exercise tolerance was achieved without an associated increase in the rate of treatment-related adverse events compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic tolerability and anti-ischemic efficacy of high dose intravenous diltiazem in patients with normal versus impaired ventricular function

OBJECTIVES

This study was designed to compare the acute systemic and coronary hemodynamic effects of high doses of intravenous diltiazem in patients with normal versus impaired left ventricular function, investigate the safety of this drug and compare its anti-ischemic potential in these two patient groups during pacing-induced stress.

BACKGROUND

Because coronary hemodynamic effects and negative inotropic properties of diltiazem are dose related, high dose intravenous diltiazem may improve anti-ischemic efficacy but may not be tolerated in patients with impaired cardiac function.

METHODS

High dose intravenous diltiazem, 0.4 mg/kg for 5 min followed by 0.4 mg/kg for 10 min, was administered to 23 normotensive patients with coronary artery disease, 11 (group A) with normal and 12 (group B) with impaired ventricular function (ejection fraction < 45%) during two identical arterial pacing stress tests performed 30 min before (pacing test I) and immediately after diltiazem (pacing test II).

RESULTS

Diltiazem was well tolerated despite high peak plasma levels, 869 +/- 152 micrograms/liter (group A) and 926 +/- 169 micrograms/liter (group B). It resulted in immediate but similar reductions in systemic resistance from 1,321 +/- 136 (control value) to 963 +/- 113 dynes.s.cm-5 (group A) and from 1,267 +/- 106 to 865 +/- 58 dynes.s.cm-5 (group B) and in mean arterial pressure from 107 +/- 3 to 93 +/- 4 mm Hg (group A) and from 103 +/- 4 to 86 +/- 4 mm Hg (group B), at 5 min after diltiazem (all p < 0.05 vs. control value). Diltiazem improved stroke output from 36 +/- 3 (control value) to 46 +/- 4 ml/beat per m2 in group B and from 44 +/- 4 (control value) to 49 +/- 5 ml/beat per m2 in group A, an effect that was significantly greater and more prolonged in group B than in group A. Although neither heart rate nor contractility was affected in either group, left ventricular end-diastolic pressure increased in group A (9 +/- 2 mm Hg to 12 +/- 1 mm Hg, p < 0.05) but not in group B. Despite similar reductions in coronary resistance and improvements in coronary flow, diltiazem consistently reduced myocardial oxygen extraction, but only in group B. Also, the anti-ischemic effects of diltiazem were more pronounced in group B. During pacing test II, myocardial lactate extraction normalized in group B (7 +/- 5% vs. -6 +/- 12% [pacing test I]) but not in group A, contractility indexes improved more and the increase in left ventricular filling pressure was reduced to a greater extent in group B. Moreover, the ischemia-induced increase in arterial pressures, observed in both groups during pacing test I, was prevented in group B but recurred in group A during pacing test II.

CONCLUSIONS

High dose intravenous diltiazem is well tolerated, augments coronary flow and improves left ventricular pump function, particularly in patients with preexisting ventricular dysfunction. As its anti-ischemic effects also appear more pronounced in the latter group, high dose diltiazem may be particularly useful when ventricular function is depressed, for example, during prolonged ischemia at rest.

Determinants and significance of diltiazem plasma concentrations after acute myocardial infarction. The Multicenter Diltiazem Postinfarction Trial Research Group

A total of 1,975 plasma diltiazem concentrations were obtained from 1,067 patients enrolled in a multicenter secondary intervention study of diltiazem after acute myocardial infarction. To evaluate the determinants and significance of diltiazem concentrations in this patient population, we related drug concentrations to a variety of clinical variables recorded on the case history forms. Multiple linear regression analysis showed that (1) time from the last drug dose, (2) drug dose taken, (3) patient height (an index of lean body weight), and (4) patient age were important determinants of plasma concentration. For an equivalent dose, plasma diltiazem concentrations in a 75-year-old patient were about double those of a 25-year-old patient. Total weight and drug dose prescribed did not significantly affect plasma concentrations. Whereas drug concentrations were higher (p = 0.01) among patients with left-sided heart failure, they were not altered by renal dysfunction, hepatic disease or beta blockers. Diltiazem concentrations were a significant determinant of diastolic arterial pressure (p less than 10(-9), but neither systolic pressure nor heart rate were significantly related to diltiazem concentration. The overall incidence of adverse experiences was not related to drug concentrations, but the occurrence of second- and third-degree atrioventricular block in the coronary care unit and the need for a temporary pacemaker were substantially higher among patients with a drug concentration greater than 150 ng/ml (7.4 and 1.9%, respectively) than among patients with lower concentrations (2.6% for atrioventricular block, 0.3% for pacemaker; p = 0.02 for each). The risk of atrioventricular block was particularly increased by high diltiazem concentrations in the face of acute inferior infarction. These results suggest that diltiazem's pharmacologic and clinical effects in a large population are concentration-related, and that the consideration of patient size, age, and left ventricular function in selecting a diltiazem dose may allow for effective drug therapy with a reduced likelihood of adverse effects.

Comparison of propranolol, diltiazem, and nifedipine in the treatment of ambulatory ischemia in patients with stable angina. Differential effects on ambulatory ischemia, exercise performance, and anginal symptoms. The ASIS Study Group

Episodes of transient myocardial ischemia during ambulatory activities are common in patients with stable coronary artery disease and who are often asymptomatic. Selection of therapy for episodes of asymptomatic ischemia is limited by a lack of direct comparative studies. To determine the most effective monotherapy for patients with stable angina and a high frequency of asymptomatic ischemic episodes, propranolol-LA (mean daily dose, 293 mg), diltiazem-SR (mean daily dose, 350 mg), nifedipine (mean daily dose, 79 mg) were each compared with placebo, each for 2 weeks, in a randomized, double-blinded, crossover trial. Entry criteria were a positive exercise treadmill test during placebo therapy characterized by 1.0 mm or more ST segment depression and angina pectoris, and six or more episodes of transient ST segment depression of 1.0 mm or more on a 48-hour ambulatory electrocardiogram. One hundred ninety-four patients were screened, 63 were eligible and received randomized therapy, of which 56 patients completed at least two of the four treatment periods and were included in an intent-to-treat analysis. Fifty patients completed all four treatment phases and were included in the protocol-completed analysis. Anti-ischemia efficacy was assessed by 48-hour ambulatory electrocardiographic monitoring, exercise treadmill tests, and anginal diaries. Ninety-four percent of all episodes of ambulatory ischemia were asymptomatic. Compared with placebo, only propranolol was associated with a marked reduction in all manifestations of asymptomatic ischemia during ambulatory electrocardiographic monitoring (2.3 versus 1.0 episodes/24 hr; mean duration of ischemia per 24 hours, 43.6 versus 5.7 minutes; both p less than 0.0001). Diltiazem's reduction of the frequency of episodes compared with placebo (2.3 versus 1.9 episodes/24 hr) was associated with a trend (p = 0.08) in the protocol-completed analysis and with a significant reduction in the intent-to-treat analysis (p = 0.03). Nifedipine had no significant effect on any measured variable of ambulatory ischemia. The dosages of medication used may have been excessive for some patients, and a more beneficial effect may have been evident at a lower dose. In contrast to the marked effects of the active agents on ambulatory asymptomatic ischemia, the effects on exercise performance and angina pectoris were slight. The active agents modestly improved treadmill exercise duration time until 1 mm ST segment depression (3%), and only propranolol and diltiazem had significant effects. Only diltiazem significantly prolonged the total exercise time. Anginal frequency was significantly decreased by both propranolol and diltiazem.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of diltiazem and long-term beta 1-adrenergic blockade on hemodynamics and blood flow during exercise in patients with stable angina pectoris

The short-term effects of oral diltiazem on hemodynamics and distribution of cardiac output at rest and during semiupright bicycle exercise were evaluated in eight patients with stable effort angina on long-term beta 1-adrenergic blockade. Cardiac output and iliofemoral blood flow were measured using thermodilution. The patients were exercised to the same work load on a bicycle before and 2 h after oral diltiazem (60 mg in two patients and 120 mg in six). At maximal exercise, diltiazem reduced heart rate from 94 +/- 5 to 88 +/- 6 beats/min (p less than 0.01), mean arterial pressure from 139 +/- 5 to 127 +/- 4 mm Hg (p less than 0.01) and systemic vascular resistance from 9.7 +/- 0.7 to 8.4 +/- 0.4 x 10(2) dynes.s.cm-5 (p less than 0.05) compared with control. During exercise, cardiac output, iliofemoral blood flow, mean pulmonary wedge pressure and mean right atrial pressure were not altered, but stroke volume increased from 119 +/- 11 to 131 +/- 10 ml (p less than 0.05). Maximal ST segment depression during exercise was decreased and angina was less. Diltiazem does not alter the distribution of the cardiac output during exercise but improves ischemia.

Usefulness of sustained-release diltiazem for stable angina pectoris

Sustained-release diltiazem, 120 and 180 mg twice daily, was assessed in a multicenter, double-blind, randomized, placebo-controlled trial in 65 stable angina patients with exercise-induced ST depression. Exercise testing was performed 12 +/- 1 hours after the last dose at the end of each of the 3 treatment weeks. Both dose levels of drug reduced spontaneous angina (p less than 0.001) and increased exercise duration (p less than 0.01) and time to 1-mm ST depression (p less than 0.001). No differences were noted between the 2 dose levels. Rate-pressure product at maximal exercise was similar for the 3 groups. Only 1 patient terminated the study because of adverse drug effects; severe adverse effects occurred in 1 placebo and 1 low-dose period. Sustained-release diltiazem is safe and efficacious monotherapy for patients with stable angina.

Effects of diltiazem alone or with isosorbide dinitrate or with atenolol both acutely and chronically for stable angina pectoris

To establish the contribution of combination therapy in stable angina, the short- and long-term effects of diltiazem (120 mg and 360 mg/day, respectively), and the additive effects of sublingual isosorbide dinitrate, 10 mg, and atenolol, 100 mg, were studied in 11 patients with chronic stable angina using an open-label sequential design. All patients underwent exercise testing without therapy, and with each drug and their combinations. Exercise time and heart rate-blood pressure product were measured at 1-mm ST-segment depression, or at peak exercise if the test result was negative. Exercise time increased from a control value of 8.0 +/- 2.3 minutes (mean +/- standard deviation) to 11.4 +/- 2.4 minutes (p less than 0.0001) after the administration of isosorbide dinitrate, to 11.3 +/- 1.8 minutes (p less than 0.001) after short-term diltiazem and to 12.4 +/- 1.5 minutes (p less than 0.001) after long-term diltiazem. The rate-pressure product increased from a control value of 19,070 +/- 3,564 to 24,431 +/- 4,795 beats/min X mm Hg (p less than 0.0001) after isosorbide dinitrate, to 22,287 +/- 4,753 beats/min X mm Hg (p less than 0.01) after short-term diltiazem and to 21,812 +/- 3,976 beats/min X mm Hg (p less than 0.007) after long-term diltiazem. The addition of atenolol to long-term diltiazem significantly reduced the rate-pressure product compared with long-term diltiazem alone (21,812 +/- 3,976 vs 13,926 +/- 2,880 beats/min X mm Hg, (p less than 0.002), although there was no further significant increase in exercise time (12.4 +/- 1.5 vs 13.3 +/- 1.6 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)

High-dose monotherapy and combination therapy with calcium channel blockers for angina. A comprehensive review of the literature

Clinical experience with the calcium channel-blocking agents has established their efficacy in the therapy of painful and silent myocardial ischemia. Questions have arisen, however, about side-effect characteristics of these medications as clinical practice has led to utilization of higher doses of individual drugs than employed in large numbers of patients in early clinical trials as well as combinations with other antianginal agents including beta-blockers. A study was undertaken to examine the published literature regarding side effects associated with high-dose versus low-dose therapy with nifedipine and diltiazem and the use of these agents in combination with beta-blockers. This investigation demonstrated that utilization of high-dose diltiazem (more than 240 mg per day) as opposed to low-dose diltiazem (no more than 240 mg per day) was associated with an increased incidence of atrioventricular block, and increased peripheral vasodilatory effects. In contrast, the use of high-dose nifedipine (more than 60 mg per day) was not associated with atrioventricular block. At clinically high dosage levels, the incidence of peripheral edema was comparable for both nifedipine and diltiazem, although low-dose nifedipine resulted in a significantly greater incidence of edema compared with low-dose diltiazem. This analysis also demonstrated that bradyarrhythmia is associated with the combination of a beta-blocking agent and either low- or high-dose diltiazem, but not with nifedipine-beta-blocker combinations. Clinical experience suggests caution in the combined use of diltiazem and a beta-blocking agent because of the demonstrated additional adverse negative chronotropic and dromotropic effects. No additional adverse electrophysiologic effects have been noted for nifedipine-beta-blocker combinations. The literature analysis supports and mirrors widespread clinical experience obtained since nifedipine and diltiazem were introduced. It should be noted, though, that combination therapy with calcium channel blockers and beta-blockers should be done with caution, since there have been occasional reports of congestive heart failure or exacerbation of angina with this combination.

The role of nitrates, beta blockers, and calcium antagonists in stable angina pectoris

Numerous controlled studies have shown that nitrates, beta blockers, and calcium antagonists are effective in the treatment of stable angina pectoris. The pharmacokinetics, pharmacodynamics, and hemodynamic effects of these agents are different, and thus combination therapy offers additive improvement and also counterbalancing of the undesirable side effects of each drug. The choice of therapy depends on the severity of symptoms, associated diseases, compliance, side effects, and status of left ventricular function. The main mechanism of improvement is a decrease in myocardial oxygen consumption, though an increase in coronary blood flow is another potential reason for the use of calcium blockers. This review considers the properties of these drugs, their mechanism of action, and the results of randomized studies.

Calcium channel antagonists. Part IV: Side effects and contraindications drug interactions and combinations

With the correct selection of drug and patient, the calcium antagonists as a group can be remarkably effective at relatively low cost of serious side effects. Almost all side effects are dose related. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil (or diltiazem) is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine which actually has the most marked negative inotropic effect. Yet caution is required when even calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide. The most marked interaction with digoxin is that with verapamil, which may raise digoxin levels by over 50%. Combination therapy of calcium antagonists with beta-blockers is increasingly common, and is probably safest in the case of dihydropyridines. Other combinations being explored are those with angiotensin-converting enzyme inhibitors and diuretics.

Combination therapy with diltiazem and nifedipine in patients with effort angina pectoris

The antianginal effects of diltiazem and nifedipine alone and in combination were evaluated in a double-blind, randomized, placebo-controlled trial in 11 patients (nine men and two women, 57 +/- 8 years old) with stable effort angina. Each patient received placebo, 30 mg of diltiazem, 10 mg of nifedipine, and 30 mg of diltiazem plus 10 mg of nifedipine four times daily for 1 week each. Antianginal efficacy was assessed by means of a treadmill exercise test. The exercise tolerance time was significantly prolonged from 235.1 +/- 52 (placebo period) to 342.2 +/- 101 sec by diltiazem (p less than .01) and to 325.6 +/- 73 sec by nifedipine (p less than .01). The drug combination further prolonged exercise time to 451.1 +/- 103 sec, which was significantly longer than the interval attained with either diltiazem (p less than .01) or nifedipine (p less than .01) alone. The plasma concentration of diltiazem was unaffected by the addition of nifedipine, whereas the plasma nifedipine concentration was significantly increased from 34.8 +/- 11 to 106.4 +/- 37 ng/ml (p less than .001) by the concomitant administration of diltiazem. These data suggest that exercise tolerance in patients with effort angina is increased by the concomitant administration of diltiazem and nifedipine associated with an increase in the nifedipine plasma concentration.

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.

Calcium channel blockers

The calcium channel blockers initially were approved for the treatment of classical and variant angina pectoris. Recent studies indicate that these agents also are useful in such diverse conditions as pulmonary and systemic hypertension, hypertrophic cardiomyopathy, arrhythmias, asthma, Raynaud's syndrome, esophageal spasm, myometrial hyperactivity, cerebral arterial spasm, and migraine.

The effects of slow channel blockers and beta blockers on atrioventricular nodal conduction

The PR interval on the electrocardiogram represents the time that it takes an impulse to travel through the atrium and atrioventricular (AV) conduction system to the ventricles. Normally, activation is slowest in the AV node, and variations in PR interval most commonly parallel changes in AV nodal activation time. The AV nodal conduction time and effective refractory period are rate dependent and, in adult humans, are usually prolonged with increasing atrial paced rates. In addition, alterations in autonomic tone effect AV nodal conduction as well as sinus rate. The effect is usually in the same direction but often to different degrees. In patients with normal AV nodal function, parasympathetic and sympathetic tone are balanced at rest, but in patients with abnormal AV conduction, the effect of the parasympathetic system is more marked. Drugs including the slow channel blockers and beta blockers, affect AV nodal function. Slow channel blockers inhibit the slow inward calcium current, which may prolong conduction and refractoriness in the AV node. However, whereas diltiazem and verapamil have been shown to prolong AV nodal conduction and refractoriness in humans, nifedipine, a potent vasodilator, cannot be used in doses large enough to affect the AV node. The increase in PR interval caused by verapamil is minimal, and at doses of less than 480 mg/d, AV block occurs infrequently. When AV block occurs, it is first degree block in most patients, and it is usually asymptomatic. The electrophysiologic effects of diltiazem are similar to those of verapamil. Beta blockers also have a negative dromotropic effect on the AV node. They prolong the AH interval and AV nodal refractory periods and may lengthen the PR interval. The prolonged PR interval rarely results in more than first degree AV block in patients receiving maintenance therapy. In selected patients, combination therapy with a slow channel blocker and a beta blocker rarely causes second-degree AV block.

Efficacy and safety of sustained-release diltiazem as replacement therapy for beta blockers and diuretics for stable angina pectoris and coexisting essential hypertension: a multicenter trial

To determine if a sustained-release form of the calcium entry blocker diltiazem would be a satisfactory substitute for the combination of beta-adrenergic blocking agent and thiazide diuretic in the treatment of systemic hypertension and angina pectoris, 38 patients were studied in a 4-center trial. Blood pressure and heart rate were measured in the supine position, immediately after and 5 minutes after standing. Modified Bruce protocol treadmill tests were performed to determine the time to onset of 1 mm ST-segment depression, time to onset of chest pain and time to termination of exercise. Diltiazem monotherapy resulted in equivalent blood pressure control in 28 of 38 patients (74%). In the remaining patients, blood pressure control was achieved with resumption of the diuretic. Blood pressure with beta blocker plus diuretic compared with diltiazem were, in the supine position 137 +/- 22/82 +/- 7 (+/- 1 standard deviation) versus 139 +/- 22/82 +/- 8 mm Hg, immediately after standing 131 +/- 20/84 +/- 9 versus 133 +/- 21/82 +/- 10 mm Hg and after standing for 5 minutes 134 +/- 19/85 +/- 8 versus 137 +/- 18/85 +/- 9 mm Hg (difference not significant for each). The heart rate with diltiazem was higher supine (67 +/- 11 versus 60 +/- 11 beats/min), standing (73 +/- 13 versus 64 +/- 14 beats/min) and 5 minutes after standing (73 +/- 14 versus 63 +/- 14 beats/min, p less than 0.01 for each).(ABSTRACT TRUNCATED AT 250 WORDS)

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

The effects of nine calcium ion antagonists on exercise tolerance, heart rate and ST-segment changes were compared with those of propranolol in two hundred and eighty patients with established chronic stable angina pectoris. These patients participated in clinical trials for anti-anginal efficacy against placebo, using identical methods and similar protocols, but the comparison reported here was retrospective. The trials were all fixed dose, and the dose was determined by previous upward titration to arrive at an average maximal tolerance level. All the drugs except prenylamine increased the exercise tolerance significantly when compared with placebo. Maximal ST-segment depression on exercise was reduced during treatment with propranolol while treatment with the calcium ion antagonists had no significant effect. The time to the development of 1 mm ST-segment depression was prolonged by all the drugs. Nifedipine, PY-108-068 and nicardipine increased the resting heart rate whereas verapamil, diltiazem, gallopamil, KB-944, prenylamine and tiapamil produced a slight reduction. Propranolol produced a highly significant reduction in the resting and maximal heart rates and the rate-pressure product, whereas gallopamil increased the rate-pressure product by +8% and prenylamine reduced it by -10%. At the doses used, diltiazem, gallopamil and verapamil produced a greater increase in exercise tolerance than did propranolol, while the other drugs were inferior. None of the calcium ion antagonists matched the increase in the time taken to develop 1 mm ST-segment depression with propranolol, although the results with verapamil and gallopamil were close. The calcium ion antagonists are effective antianginal agents which produce their effects by mechanisms which are very different to the beta-adrenoreceptor blocking agents.

Comparative effects of prolonged therapy with four calcium ion antagonists (diltiazem, nicardipine, tiapamil and verapamil) in patients with chronic stable angina pectoris

The comparative effects of prolonged chronic therapy with diltiazem, nicardipine, tiapamil and verapamil on exercise tolerance, ST-segment changes and heart rate were examined in 63 patients with established chronic stable angina pectoris. Multistage computer-assisted symptom-limited treadmill exercise tests were performed after 2 weeks of placebo ("baseline") and then after 4 months of open-label chronic drug therapy. Diltiazem improved the exercise duration by 95% (p less than 0.001), nicardipine by 45% (p less than 0.001), tiapamil by 69% and verapamil by 79% (p less than 0.001). Maximal ST-segment depression was not altered by any of the drugs, but time to the development of 1 mm ST-segment depression was significantly improved in all cases. Diltiazem and verapamil reduced the heart rate at rest significantly by 6 and 8 beats/minute, respectively, whereas nicardipine increased it by 10 beats/minute (p less than 0.02), and tiapamil did not produce any significant change. Maximal heart rate at the peak of exercise was increased by 14% with nicardipine (p less than 0.001) and 6% with verapamil (p less than 0.05), whereas diltiazem and tiapamil did not produce any appreciable effect. The rate-pressure product at the peak of exercise remained unaltered with diltiazem, tiapamil and verapamil, but with nicardipine it increased significantly to 222 +/- 10 units from a baseline of 175 +/- 6 units with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of diltiazem and propranolol on myocardial ischaemia during unrestricted daily life in patients with effort-induced chronic stable angina pectoris

To examine the effect of diltiazem 60 mg thrice daily and propranolol 80 mg thrice daily on myocardial ischaemia during unrestricted daily life, we have studied 14 patients with established effort-induced chronic stable angina pectoris in a double-blind crossover study. Ambulatory electrocardiographic monitoring was performed using frequency modulated (FM) tape recorder after 2 weeks of placebo therapy and at the end of each 4 week treatment period for a minimum of 24 h. The mean (+/- SEM) number of episodes of ST-segment depression greater than 1 mm during placebo treatment were 97 +/- 28, and these fell to 54 +/- 27 during diltiazem treatment (p less than 0.05) and to 12 +/- 6 during propranolol treatment (p less than 0.02). The maximal depth of ST-segment depression in 24 h, which indicates the severity of the episode, was 3.3 +/- 0.4 mm during placebo, 2.5 +/- 0.2 mm during diltiazem (p less than 0.05), and 1.6 +/- 0.5 mm during propranolol (p less than 0.01). Both diltiazem and propranolol treatment produced significant reduction in the total area of ST-segment depression observed during 24 h. A uniform reduction in the mean heart rate during the 24 h was observed during propranolol therapy and not during diltiazem therapy. Both diltiazem and propranolol treatment improved indices of myocardial ischaemia during daily normal unrestricted life, as measured by ambulatory ST-segment monitoring in patients with established chronic stable angina pectoris. Their differing effects on heart rate suggest that they act by different mechanisms.

Does placebo improve indexes of effort-induced myocardial ischemia? An objective study in 150 patients with chronic stable angina pectoris

The effects of placebo were studied in 150 patients (135 men, 15 women) aged 42 to 75 years with stable exertional angina pectoris, using multistage graded exercise testing. Treadmill exercise, using on-line computer analysis of the electrocardiogram, was performed after a basal period, during which time the patients had no treatment for 2 weeks, and after 2 weeks of placebo therapy. Mean exercise time during no treatment was 6.0 +/- 0.2 minutes and during placebo was 6.1 +/- 0.2 minutes (difference not significant). Similarly, time to development of 1 mm of ST-segment depression of 4.0 +/- 0.2 minutes without treatment was 4.1 +/- 0.2 minutes after 2 weeks of placebo therapy (difference not significant). Placebo failed to show any effect on rest or maximal heart rate or on maximal ST-segment depression. It also failed to increase exercise tolerance or to improve other objective indexes of effort-induced myocardial ischemia in both single-and double-blind protocols in patients with stable exertional angina pectoris. Therefore, placebo control of antianginal drug trials that use exercise testing for evaluation of effect is unnecessary and can be omitted.

Effort angina with adequate beta-receptor blockade: comparison with diltiazem alone and in combination

Calcium channel blockers and beta-receptor blockers improve symptoms of myocardial ischemia by potentially different mechanisms. Accordingly, combination therapy may entail additive benefits. Twenty-four patients with symptomatic stable effort angina despite full beta-blockade were randomized to a double-blind Latin square protocol in which they received propranolol in a dose producing full beta-receptor blockade, diltiazem, 240 mg/day, in divided doses and a combination of propranolol and diltiazem, 240 or 360 mg/day. Treadmill testing (Bruce protocol) was utilized to assess exercise tolerance, radionuclide ventriculography to assess left ventricular function and clinical follow-up to assess adverse effects and overall clinical response. Comparable treadmill exercise times were observed with monotherapy (344 +/- 83 seconds with propranolol and 341 +/- 87 seconds with diltiazem) and the lower dose combination (361 +/- 87 seconds). With propranolol and diltiazem, 360 mg/day, however, there was a significant increase in treadmill time (393 +/- 106 seconds; p less than 0.05). In five patients whose treadmill exercise was limited by angina on all therapies, there was a significant improvement in the time to onset of chest pain with both low dose and high dose combinations (311 +/- 71 seconds, p less than 0.05 and 336 +/- 76 seconds, p less than 0.01, respectively). Improved treadmill performance was supported by the clinical response, while an increase in adverse effects was not observed. Thirteen of 24 patients blindly selected the higher dose diltiazem combination as their optimal therapy. Left ventricular dilation was observed (by radionuclide ventriculography) in response to exercise in each phase of therapy; this was related to stress-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and safety of sustained-release diltiazem in stable angina pectoris

The safety and efficacy of a sustained-release preparation of diltiazem (diltiazem-SR), with dose levels of 240 and 360 mg/day, were assessed in 18 patients with stable angina of effort. A double-blind, placebo-controlled, randomized, crossover protocol was used. Diltiazem-SR, when given twice daily, reduced the frequency of weekly anginal attacks from 9.3 +/- 10.4 with placebo to 3.7 +/- 4.7 with 240 mg/day and to 3.1 +/- 4.7 with 360 mg/day (both p less than 0.01 compared with placebo). Treadmill time was increased from 410 +/- 180 seconds during the placebo phase to 519 +/- 177 seconds during the 240-mg/day dose and to 506 +/- 182 seconds during the 360-mg/day dose of diltiazem-SR (both p less than 0.01 compared with placebo). The time to the onset of angina and ischemic ST-segment depression were similarly prolonged by both doses of diltiazem-SR. The beneficial effects of diltiazem-SR appeared partly due to a reduction in the heart rate during submaximal exercise. Diltiazem-SR is effective and safe for the treatment of angina of effort when given twice daily.

Ambulatory monitoring and exercise testing in the evaluation of a new long-acting calcium ion antagonist KB-944 (Fostedil) for the treatment of exertional angina pectoris

The anti-anginal effects of KB-944 (Fostedil), a new calcium ion antagonist with a half life of approximately 23-28 hr, were evaluated in 20 patients with exertional angina pectoris in a placebo-controlled single-blind dose titration trial. Ambulatory monitoring and multistage treadmill exercise with computer-assisted electrocardiographic analysis was performed after 2 weeks of placebo therapy and after two 2-weekly periods of KB-944 therapy. The mean (+/- SEM) exercise time to the development of angina on treadmill walking increased from 6.9 +/- 0.4 min on placebo to 9.4 +/- 0.5 min on KB-944 100 mg/day (P less than 0.001) and 9.7 +/- 0.8 min on KB-944 200 mg/day (P less than 0.001 vs placebo and not significant vs KB-944 100 mg/day). The time to the development of 1 mm ST-segment depression of 5.3 +/- 0.4 min on placebo increased to 6.5 +/- 0.5 and 6.6 +/- 0.5 min on KB-944 100 and 200 mg/day, respectively (P less than 0.01 vs placebo). The heart rate at rest of 77 +/- 3 beats/min on placebo was reduced to 68 +/- 3 beats/min on KB-944 100 mg/day (P less than 0.001) and 71 +/- 2 beats/min on KB-944 200 mg/day (P less than 0.01). The maximal heart rate and the rate-pressure product were not altered by KB-944 therapy. One patient developed unstable angina during the treatment phase of KB-944 200 mg/day and was withdrawn. Five patients complained of dyspepsia and one of headache and lethargy during KB-944 200 mg/day. One patient developed ventricular tachycardia during treadmill testing while on KB-944 200 mg/day. The 24-hr ambulatory monitoring data confirmed the findings of exercise testing. KB-944 (Fostedil) in a dose of 100 mg once daily was well tolerated as compared to KB-944 200 mg once daily and both the doses were equally effective. The drug merits further evaluation for the treatment of exertional angina pectoris.

Efficacy of diltiazem for medically refractory stable angina: long-term follow-up

To assess the efficacy of long-term diltiazem therapy when added to beta blockers and nitrates, we prospectively studied patients with chronic exertional angina who were determined to have medically refractory angina pectoris which was too severe to enter placebo-controlled studies. The mean follow-up time was 24.6 months (8-47 months) and all patients were seen every 2-4 months. Angina frequency decreased from a prediltiazem frequency of 9.5 episodes per week (1-40 per week) to 3.3 attacks per week (0-21 per week) at 6 months and 3.3 attacks per week (0-40 per week) at the patients's last evaluation. Similar reductions in nitroglycerin consumption were reported. Five patients had an increase in angina frequency during the mean 24.6 months of follow-up, which necessitated coronary bypass surgery, 8, 10, 12, 19, and 23 months after study entry, respectively. Diltiazem daily dosage ranged from 120 to 480 mg/day, the mean daily dose was 298 mg/day. Twenty (65%) patients remained on beta-blocker therapy and 19 (61%) patients on nitrate therapy in an effort to achieve a completely pain-free state. New cardiovascular events were documented in 3 patients during the follow-up period, with one patient having an uncomplicated myocardial infarction at 6 months, one patient hospitalized for prolonged chest pain at 2 months, and one patient dying following cardioversion for unrelated atrial fibrillation at 14 months poststudy entry. Adverse effects were reported during 19 of the 354 patient visits, but no patient had to stop therapy because of these. Sinus bradycardia required reduction of beta-blocker dosage in three patients and prolonged PR interval was observed in two additional patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute hemodynamic and electrophysiologic effects of propranolol in patients receiving diltiazem

Because the combined use of a beta-adrenergic blocking agent and a calcium antagonist may be beneficial in some patients with severe angina, the acute hemodynamic and electrophysiologic effects of intravenous propranolol in the presence and absence of oral diltiazem treatment was studied. In 22 patients (11 men, 11 women, mean age 50 years), 12 receiving diltiazem (mean 243 mg/day, range 180 to 360) and 10 not receiving diltiazem, hemodynamic and electrophysiologic variables were measured before and 5 minutes after intravenous propranolol (0.1 mg/kg). Cardiac index (by thermodilution) and left ventricular (LV) peak dP/dt fell and LV end-diastolic pressure increased similarly in both groups. Mean systemic arterial pressure was unchanged. Coronary sinus blood flow (by thermodilution) decreased slightly in patients receiving diltiazem and was unchanged in those not receiving it. Propranolol caused a similar reduction in heart rate and increase in atrio-His conduction in both groups. Thus, when intravenous propranolol is given to patients with normal or only mildly depressed LV systolic function, the hemodynamic and electrophysiologic effects are similar in those receiving and not receiving oral diltiazem.

Superiority of combined diltiazem and propranolol therapy for angina pectoris

Twenty-four patients with stable angina were evaluated in a 14 week crossover trial. A single-blind placebo period (baseline 1) was followed by two double-blind periods evaluating maximum tolerated doses of diltiazem (up to 360 mg daily) vs placebo. Over the next 1 to 4 weeks, propranolol was started and increased until clinically documented beta-blockade was achieved (baseline 2). The final phase consisted of a pair of evaluation periods comparing propranolol plus the maximum tolerated dose of diltiazem to propranolol and placebo. The daily rate of angina attack was 1.6 during baseline, was unchanged during placebo therapy, but fell during treatment with diltiazem to 0.6 (p less than .005). With the addition of diltiazem to propranolol, the angina rate was improved (0.3) compared with that with either propranolol alone (0.6) or propranolol and placebo (0.5) (p less than .01). Total exercise duration during baseline 1 was 360 sec and increased to 497 sec with diltiazem, 481 sec with propranolol, and 527 sec with the combination of diltiazem and propranolol. Two patients with reduced ejection fractions developed congestive heart failure with propranolol. The combination of diltiazem and propranolol similarly resulted in congestive heart failure in one patient who had tolerated both drugs alone.

Short- and long-term treatment of stable effort angina with nicardipine, a new calcium channel blocker: a double-blind, placebo-controlled, randomised, repeated cross-over study

This study evaluated 1 year the efficacy of therapy with nicardipine in patients with chronic stable angina pectoris. Twenty-five male patients were entered. After a placebo run-in phase, the patients received nicardipine 30 mg, nicardipine 40 mg, and placebo, three times daily given in random, double-blind manner for 8 weeks. A double-blind, cross-over study comparing nicardipine with placebo was then undertaken. After 5 months of open treatment with nicardipine 90 or 120 mg day-1, patients received either placebo or nicardipine for 3 weeks, each followed by the alternative treatment for an additional 3 weeks and further open-label treatment with nicardipine for another 3-5 months. There were no significant changes in the PR, QRS or QT intervals, or in the QRS pattern during the short-term and long-term studies. There were no significant differences in mean heart rate after nicardipine compared with baseline. During treatment with nicardipine 120 mg day-1, patients reported significantly fewer anginal attacks compared with placebo, and nitroglycerin consumption also decreased. Nicardipine increased treadmill time, time to onset of angina, and time to one mm ST segment depression. These effects were maintained after 6 months of continued nicardipine therapy. Adverse effects were minor and well tolerated and included headache, dizziness, gastrointestinal upset, flushing paraesthesia and pedal oedema. Abrupt withdrawal of nicardipine at the end of the study resulted in a rapid return of the original symptoms but without further deterioration from the baseline measurements. Nicardipine was effective in the treatment of stable effort angina pectoris; this benefit was maintained for the entire year of treatment.

The efficacy and safety of high-dose verapamil and diltiazem in the long-term treatment of stable exertional angina

The efficacy and safety of high-dose verapamil (480 mg/day) and diltiazem therapy (360 mg/day) were compared in separate cohorts of 26 and 20 patients, respectively. All patients had stable exertional angina and underwent an initial 6-week double-blind, placebo-controlled, randomized phase followed by a 12-month open-label period. Angina attacks were reduced by verapamil (6.3 +/- 7.5 to 2.5 +/- 4.1 attacks per week, p less than 0.001) and by diltiazem (9.2 +/- 7.5 to 3.0 +/- 3.1 attacks per week, p less than 0.001), while treadmill time increased with both verapamil (372 +/- 132 to 444 +/- 108 s, p less than 0.001) and diltiazem (412 +/- 175 to 536 +/- 164 s, p less than 0.001) during the short-term study. Both agents continued to show similar salutory effects at the end of one year. The beneficial effects of both drugs appeared to be related in part to a reduction of the rate-pressure product during submaximal exercise (12% by verapamil, 7% by diltiazem, both p less than 0.05). Adverse effects were few and consisted primarily of mild constipation in six patients taking verapamil, and pedal edema and transient flushing in 2 patients each using diltiazem. Thus, high-dose verapamil and diltiazem have similar beneficial effects and are safe for the long-term treatment of effort-related angina pectoris.

Short- and long-term efficacy of nicardipine, assessed by placebo-controlled single- and double-blind crossover trials in patients with chronic stable angina

The efficacy of nicardipine, a new calcium ion antagonist, was studied in 39 patients aged 42 to 70 years with chronic stable angina in two different placebo-controlled single- and double-blind crossover trials and with long-term follow-up, using serial quantitated exercise testing and ambulatory ST segment monitoring. In the first study the minimal effective dose was determined, and in the repeat study the effects of three different dose levels were evaluated. Treadmill exercise testing was performed at the end of each 2 week treatment period with on-line computer analysis of the electrocardiogram. The mean (+/- standard error of the mean) exercise time was 6.8 +/- 0.7 minutes on placebo and 7.0 +/- 0.8 minutes during treatment with nicardipine, 60 mg/day (p = NS). This increased to 8.7 +/- 0.8 (p less than 0.001) and 9.2 +/- 0.9 minutes (p less than 0.001) with 90 and 120 mg/day, respectively. The mean heart rate at rest during placebo administration was 75 +/- 2 beats/min and increased to 85 +/- 3, 84 +/- 2 and 88 +/- 3 beats/min (p less than 0.02, p less than 0.01, p less than 0.01, respectively) at each dose level. The time taken to develop 1 mm of ST segment depression was prolonged from 4.8 +/- 0.6 minutes during placebo administration to 5.3 +/- 0.7 (p = NS), 6.4 +/- 0.7 (p less than 0.01) and 6.7 +/- 0.8 minutes (p less than 0.001), respectively, at each dose level. The improvement achieved after 2 weeks of nicardipine, 120 mg daily, was maintained over a period of 6 months of follow-up. Three patients were withdrawn, one taking 60 mg of nicardipine, one taking 90 mg of nicardipine and one taking placebo, but the overall incidence of side effects was low. Nicardipine is an effective antianginal agent with an optimal dose of 90 to 120 mg/day.

Long-term efficacy of diltiazem assessed with multistage graded exercise tests in patients with chronic stable angina pectoris

The long-term efficacy of diltiazem, 360 mg/day, in patients with grade II or III stable exertional angina pectoris (Canadian Cardiovascular Society criteria) was assessed by multistage graded exercise tests. Seventeen patients undertook a placebo-controlled, double-blind, dose-titration protocol and all received long-term therapy. Exercise tests were performed at the end of 2 weeks of placebo treatment and after 6, 18, 26, 40 and 52 weeks of diltiazem, 360 mg/day. All patients had angina during treadmill testing with placebo and the mean (+/- standard error of the mean) exercise time was 5.8 +/- 0.7 minutes. This increased to 10.8 +/- 1.0 minutes after 6 weeks, 11.3 +/- 1.1 minutes after 18 weeks, 11.4 +/- 1.1 minutes after 26 weeks, 12.9 +/- 1.2 minutes after 40 weeks and 11.6 +/- 1.3 minutes after 52 weeks of continuous diltiazem therapy (p less than 0.001 vs placebo at all stages). Four patients were withdrawn after 26 weeks of treatment; one patient underwent coronary artery bypass surgery and 3 patients required the addition of beta-adrenoreceptor blocking agents. In 1 patient an irritant rash developed on the torso, legs and arms after 39 weeks of diltiazem and disappeared after discontinuing the drug. One patient complained of swelling and stiffness of the fingers and 3 patients complained of shoulder and elbow pain. Another patient had a myocardial infarction after 8 weeks of diltiazem treatment and died. No other adverse effects were observed during this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of diltiazem at two dose levels with propranolol for treatment of stable angina pectoris

Two dose levels of diltiazem with propranolol were compared in the management of chronic stable angina. Two groups of patients were treated for alternate periods of 4 weeks with each drug in a double-blind crossover with computer-assisted maximal treadmill tests and ambulatory ST-segment monitoring for evaluation of efficacy and safety. In 12 patients who received diltiazem, 180 mg/day, the time to development of angina increased from 5.9 +/- 0.7 minutes (+/- standard error of the mean) during placebo treatment to 8.3 +/- 0.8 minutes during diltiazem treatment and to 9.2 +/- 0.8 minutes with propranolol, 240 mg/day. Three patients became angina-free when they were treated with both drugs. Among 12 patients who received diltiazem, 360 mg/day, 1 patient became angina-free during treatment with both drugs and 1 became angina-free with diltiazem only. The mean exercise time increased from 5.8 +/- 0.7 minutes with placebo to 8.6 +/- 1.0 minutes with diltiazem, 360 mg/day, and to 8.2 +/- 0.6 minutes with propranolol, 240 mg/day. Analysis of variance showed no difference in efficacy between the 2 doses of diltiazem or between the 2 drugs. Ambulatory heart rate was reduced both during the day and at night with both drugs and significantly more with propranolol than with diltiazem treatment. Except for 1 patient in whom a rash developed when given diltiazem, 180 mg/day, and another who had both a rash and first-degree heart block with diltiazem, 360 mg/day, both drugs were well tolerated. Thus, diltiazem in a daily dose of 180 or 360 mg/day is as effective as propranolol for the treatment of chronic stable angina.