Hemodynamic and clinical effects of combined verapamil and propranolol therapy in angina pectoris

Heart insufficiency after combination of verapamil and metoprolol: A fatal case report and literature review

The combination of verapamil or diltiazem with beta-blockers should be avoided because of potentially profound adverse effects on AV (atrioventricular) nodal conduction, heart rate, or cardiac contractility. This effect is unpredictable but may be enhanced due to CYP2D6 poor metabolizer status which could be a special vulnerability factor.

Calcium Antagonists for Perioperative Blood Pressure Control

Calcium entry blockers constitute three major classes of pharmacologic agents: phenylalkylamines (eg, verapa mil), benzothiazepines (eg, diltiazem), and dihydropyri dines (eg, nifedipine). The effectiveness of all types of calcium channel blockers in the prevention and treat ment of coronary artery disease as well as chronic and acute hypertension is undisputable. Their beneficial clinical effects may be due to peripheral and coronary vasodilatation, resulting in reduction in myocardial oxy gen consumption, and an increase in myocardial oxy gen supply in addition to their antispasmodic effect and the ability to prevent intracellular calcium overload. For the management of perioperative hypertension develop ing in patients undergoing cardiac or noncardiac sur gery, the dihydropyridines appear to be especially suit able. Intravenous (IV) formulations of nifedipine, nicardipine, and isradipine have been successfully used in this setting. At the present time, nicardipine is the most widely used IV dihydropyridine. This is due to its potent afterload-reducing activity and relatively short duration of action, although its effect may increase the longer the drug is being infused. The ideal drug for perioperative blood pressure control should be one with the pharmacodynamic profile of the vascular selec tive dihydropyridines, but with an ultrashort duration of action.

Sinus arrest and moderate hyperkalemia

Hyperkalemia, especially if severe, is a frequent cause of cardiac rhythm pathologies. Sinus arrest of sudden onset is more likely to occur when the potassium level is very high (e.g. > 8 mmol/l) but in concomitance with negative chronotropic drugs it may occur even in presence of a moderate hyperkalemia. This case report highlights the fact that these kinds of drugs, especially in combination, are probably to be avoided in patients at risk of developing hyperkalemia (e.g. diabetics, renal failure, etc.), even of moderate degree, considering this life-threatening cardiac complication.

Cardiovascular adverse drug reaction associated with combined beta-adrenergic and calcium entry-blocking agents

Numerous studies have shown a beneficial effect of combination therapy with beta-blockers and calcium antagonists in patients with anginal syndrome and/or hypertension. However, because both agents exert a negative chronotropic effect, their combined use may cause bradyarrhythmias with resultant symptoms of cerebral, coronary, and systemic hypoperfusion. We describe our clinical experience with patients who had cardiovascular adverse drug reactions (CVADRs) with combination therapy. This prospective study included 26 patients who had CVADRs among 2,574 admissions during a 2-year period. The study group included 14 men and 12 women with a median age of 73 years. Various combinations of calcium antagonists and beta-blockers were associated with the CVADRs. The most frequent pharmacologic combination was diltiazem plus propranolol. The CVADRs were the cause for hospital admission in 10 patients, an associated cause in nine patients, and developed during hospitalization in seven patients. Cardiac bradyarrhythmias were found in 22 patients. These rhythm abnormalities resolved within 24 h after discontinuation of the offending drugs. Temporary transvenous pacemaker insertion was necessary in only one patient with complete atrioventricular block. Twenty-two patients recovered, two patients died of pump failure not associated with CVADRs, and in two patients, the CVADRs contributed to the patients' death. CVADRs are not uncommon in elderly patients with ischemic heart disease and/or hypertension treated with the concomitant use of calcium antagonist and beta-adrenergic blocking drugs. Use of calcium antagonist plus beta-blocker may unpredictably cause serious hemodynamic events, marked suppression of sinus node activity, and prolongation of atrioventricular conduction in some patients. Enhanced therapeutic monitoring may be warranted when calcium antagonists are combined with beta-blockers.

Calcium antagonists. Drug interactions of clinical significance

The interaction of calcium antagonists, including the dihydropyridine calcium antagonists (e.g. nifedipine), verapamil and diltiazem, with drugs from other classes has major clinical ramifications as the use of drug combinations increases in frequency. Combinations are used in the treatment of disorders ranging from hypertension to cardiac rhythm disturbances, angina pectoris and peripheral vasospastic disease. In this era of organ transplantation, drugs like cyclosporin are coming into potential conflict with an ever-growing list of drugs. Drug combinations used as part of long term therapies are also making their appearance in toxic drug reactions, including antituberculous and anticonvulsant agents. Bronchodilators and H2-blockers also fall into this category of potential culprits of combined drug toxicity, and the interactions of calcium antagonists with beta-blockers and antiarrhythmic agents are also becoming a matter of concern.

Comparative haemodynamic effects of verapamil, flecainide, amiodarone and sotalol in the conscious rabbit

1. The effect of intravenous boluses of verapamil (0.15 mg/kg), flecainide (2 mg/kg), amiodarone (5 mg/kg), and sotalol (1.5 mg/kg) on mean arterial pressure, heart rate (HR), cardiac output (CO), total peripheral resistance (TPR), and peak rate of change of left ventricular pressure (LV dP/dt) were assessed in the conscious rabbit. 2. All four drugs had negative inotropic effects: verapamil reduced peak LV dP/dt by 19 +/- 4% (mean +/- s.e.m.; P < 0.01), flecainide by 27 +/- 9% (P < 0.001), amiodarone by 11 +/- 2% (P < 0.01) and sotalol by 13 +/- 3% (P < 0.01). 3. The drugs had different effects on CO as a result of differences in their actions on peripheral blood vessels: verapamil and amiodarone produced, respectively, a 12 +/- 4% (P < 0.03) and 16 +/- 6% (P < 0.01) increase in CO associated with a substantial vasodilatory effect (TPR reduced 15 +/- 7% [P < 0.05] and 20 +/- 5% [P < 0.01], respectively). Flecainide caused only a small (6 +/- 1%; P < 0.01) increase in CO and sotalol had no effect on either CO or TPR. 4. Bolus intravenous injections of verapamil, flecainide and amiodarone produced an increase in HR, while sotalol reduced HR by 10 +/- 2% (P < 0.01). The increase in HR and cardiac output seen with verapamil, flecainide and amiodarone was in part secondary to reflex increase in sympathetic tone and these changes were abolished after total cardiac autonomic blockade. 5. The modest reduction in cardiac performance associated with sotalol was abolished by cardiac autonomic blockade, suggesting that the predominant effect of sotalol on contractility was mediated through its beta-adrenoceptor blocking effect.

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.

Interactions between verapamil and metoprolol in the developing chick embryo heart

A calcium blocking agent, verapamil, and a beta 1-adrenoreceptor blocking agent, metoprolol, were administered alone or in combination to 4-day-old chick embryos (Hamburger-Hamilton developmental stage 24). Embryos co-administered with verapamil (0.05 nmol) and metoprolol (0.1 or 1.0 nmol), neither of which alone caused significant teratogenicity, showed cardiovascular malformations, including ventricular septal defects associated with or without dextroposition of the aorta (overriding aorta). The alterations of calcium movement into the myocyte and/or the haemodynamic change following impaired calcium transport are suggested to be possible causative factors.

Evaluation of potential pharmacodynamic and pharmacokinetic interactions between verapamil and propranolol in normal subjects

1. Potential pharmacodynamic and pharmacokinetic interactions between verapamil and propranolol were evaluated in two double-blind, randomised, balanced, crossover studies employing the same six healthy males. 2. The first study examined the effect of repeated propranolol administration on the pharmacodynamics and pharmacokinetics of verapamil after single oral and intravenous doses. The second explored the pharmacodynamics and pharmacokinetics of verapamil and propranolol alone and in combination after single and repeated oral doses. 3. The magnitude of the prolongation of PR interval induced by oral and intravenous verapamil was not affected by pre-treatment with propranolol. When verapamil and propranolol were co-administered as single doses, effects on PR interval were additive but, following repeated doses, a trend towards greater than additive prolongation was seen. The arithmetic sum of the effects of the two drugs was 23% (95% C.I. 8-38%) but the measured increase after the combination was 40% (95% C.I. 26-54%). 4. The extent of reduction in heart rate and blood pressure at rest and after exercise following repeated doses of propranolol was not influenced by single oral or intravenous doses of verapamil. The heart rate and blood pressure responses to single and repeated oral doses of verapamil and propranolol in combination were significantly greater than those after either drug alone and approximated to the arithmetic sum of the individual responses. 5. Although repeated administration of propranolol reduced hepatic blood flow as assessed by indocyanine green clearance, there was no evidence of an interaction between the drugs at this level. 6. The pharmacokinetics of verapamil and norverapamil were not significantly affected by prior propranolol. After single doses of verapamil and propranolol in combination, the maximum plasma concentration of propranolol was increased and the oral clearance of verapamil reduced. No pharmacokinetic interaction was observed after repeated doses. 7. These findings provide little evidence of a pharmacodynamic or pharmacokinetic interaction between verapamil and propranolol in normal subjects. Most of the haemodynamic responses to these drugs in combination can be explained by additive drug effects but an interaction affecting AV conduction after repeated doses cannot be excluded. The minor pharmacokinetic interaction between the drugs is unlikely to be relevant to the pharmacodynamic changes.

Verapamil. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in hypertension

Although verapamil is a well-established treatment for angina, cardiac arrhythmias and cardiomyopathies, this review reflects current interest in calcium antagonists as anti-hypertensive agents by focusing on the role of verapamil in hypertension. Verapamil is a phenylalkylamine derivative which antagonises calcium influx through the slow channels of vascular smooth muscle and cardiac cell membranes. By reducing intracellular free calcium concentrations, verapamil causes coronary and peripheral vasodilation and depresses myocardial contractility and electrical activity in the atrioventricular and sinoatrial nodes. Verapamil is well suited for the management of essential hypertension since it produces generalised systemic vasodilation resulting in a marked reduction in systemic vascular resistance and, consequently, blood pressure. Evidence from clinical studies supports the role of oral verapamil as an effective and well-tolerated first-line treatment for the management of patients with mild to moderate essential hypertension. Clinical studies have shown that verapamil is more effective the higher the pretreatment blood pressure and some authors have found a more pronounced antihypertensive effect in older patients or in patients with low plasma renin activity. Sustained release verapamil formulations are available for oral administration which, as a single daily dose, are as effective in lowering blood pressure over 24 hours as equivalent doses of conventional verapamil formulations given 3 times daily. As a first-line antihypertensive agent, oral verapamil is equivalent to several other calcium antagonists, beta-blockers, diuretics, angiotensin-converting enzyme (ACE) inhibitors and other vasodilators, and is not associated with many of the common adverse effects of these treatments. Verapamil may be preferred as an alternative first-line antihypertensive treatment to diuretics in elderly patients because it has similar efficacy in these patients without causing the adverse effects commonly linked with diuretic treatment. Furthermore, because verapamil does not cause bronchoconstriction, it may be used in preference to beta-blockers in patients with asthma or chronic obstructive airway disease. Reflex tachycardia, orthostatic hypotension or development of tolerance is not evident following verapamil administration. As a second- or third-line treatment for patients refractory to established antihypertensive regimens, verapamil produces marked blood pressure reductions when combined with diuretics and/or ACE inhibitors, beta-blockers and vasodilators such as prazosin.(ABSTRACT TRUNCATED AT 400 WORDS)

Safety and efficacy of isradipine, alone and in combination, in the treatment of angina pectoris

Five hundred ninety outpatients aged 18 years or older with stable angina pectoris entered a multicenter, single-blind, nonrandomized, baseline-controlled study to assess the efficacy, safety, and tolerability of isradipine in doses of 2.5, 5, or 7.5 mg three times daily for 12 weeks, following a two-week placebo "washout" period. Patients were assessed at the initial visit and, thereafter, every two weeks with a final evaluation at Week 14. The final mean dose was 5.9 mg three times daily. Overall, isradipine was found to reduce significantly the angina attack rate and nitroglycerin consumption in patients with chronic, stable, effort-induced angina pectoris. Isradipine was generally well tolerated when prescribed alone or with concomitant beta-blocker medication.

Effect of calcium entry and beta blockade during infrarenal aortic clamping

Clamping and declamping during aortic surgery produce a hemodynamically significant myocardial stress. The cardiovascular (CV) response to this stress may be adversely altered by calcium antagonists and beta-adrenoreceptor blockade employed to control symptomatic coronary artery disease. This study evaluated the effect of verapamil (V), propranolol (P), and their combination (P + V) on the CV response to infrarenal abdominal aortic cross-clamping and declamping in anesthetized dogs. Six dogs received P as a bolus of 0.5 mg/kg 20 min before clamping. Six additional dogs received V as a 300 micrograms/kg bolus followed by a V infusion of 6 micrograms/kg/min for 20 min before clamping. A third group of six dogs received the P bolus followed 20 min later by the V regimen (P + V). In both the V and P + V groups, 6 micrograms/kg/min V was infused throughout the clamping and declamping sequence. A fourth group of six control dogs received no cardioactive drugs during the experiment. Heart rate, mean aortic blood pressure, left ventricular end-diastolic pressures, peak rate of rise of left ventricular pressure, cardiac output, and systemic vascular resistance were measured in all animals before aortic cross-clamping, at 5 and 40 min after clamping, and 5 min after declamping. The results demonstrated additive negative chronotropic and inotropic properties of P + V therapy with a more significantly adverse effect than that of either drug alone. The implications of this study warrant added caution when patients treated with these drugs undergo abdominal aortic surgery.

Calcium channel blockers in systemic hypertension

Alterations in transmembrane flux of calcium ions may be playing a role in the pathophysiology of systemic hypertension. Calcium channel blockers have been shown to be effective antihypertensive drugs with excellent safety profiles. They are efficacious in the long term treatment of systemic hypertension in all population subgroups, and have special applicability for treating patients with hypertensive urgencies and individuals with concomitant diseases such as angina pectoris and arrhythmias.

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.

Prognostic importance of the immediate hemodynamic response to nifedipine in patients with severe left ventricular dysfunction

To determine the clinical significance of the occurrence of hemodynamic deterioration after the administration of calcium channel blocking drugs, nifedipine (20 mg orally) was administered to 29 patients with severe left ventricular dysfunction. Thirteen patients showed hemodynamic improvement with the drug (Group 1), as shown by a notable increase in cardiac index associated with a modest decrease in mean arterial pressure. The other 16 patients exhibited hemodynamic deterioration after nifedipine (Group 2), as reflected by a decline in right and left ventricular stroke work indexes accompanied by a marked hypotensive response. These differences were not related to differences in the peripheral vascular response to nifedipine, because both groups showed similar decreases in systemic and pulmonary vascular resistances. Groups 1 (hemodynamic improvement) and 2 (hemodynamic deterioration) were similar with respect to all demographic variables and pretreatment left ventricular performance (cardiac index, left ventricular filling pressure and systemic vascular resistance). Yet, the 1 year actuarial survival in patients in Group 1 was substantially better than that in patients in Group 2 (67 versus 23%, p = 0.009). Group 2, however, had higher values for plasma renin activity (17.7 +/- 6.0 versus 4.3 +/- 1.4 mg/ml per h, p less than 0.05), lower values for serum sodium concentration (134.6 +/- 1.2 versus 139.2 +/- 0.6 mEq/liter, p less than 0.05) and higher values for mean right atrial pressure (15.8 +/- 2.0 versus 7.9 +/- 1.4 mm Hg, p less than 0.01) than did patients in Group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of nisoldipine combined with beta-adrenergic-blocking drugs in the treatment of chronic stable angina

A double-blind, placebo-controlled study was performed to assess whether a new calcium antagonist, nisoldipine, in doses of either 5 mg or 10 mg daily, in combination with beta-adrenergic-blocking drugs (combination therapy) was more effective than beta-adrenergic-blocking drugs alone (single therapy) in the treatment of chronic stable angina. Treatments were assessed at two-week intervals, using exercise electrocardiography and patients' anginal diaries. A significant improvement in exercise capacity and reduction in anginal attacks occurred only during nisoldipine (10 mg daily) combination therapy compared with single therapy. Mean exercise time increased from 419 +/- 146 s (single) to 454 +/- 158 s (p less than 0.02) after combination therapy. Exercise time to onset of 1 mm ST-segment depression improved from 326 +/- 145 s (single) to 331 +/- 139 s after combination therapy, although the change was not significant. Mean number of anginal attacks decreased from 21 +/- 22 (single to 15 +/- 19 (p less than 0.01) during combination treatment, with an associated significant reduction in glyceryl trinitrate consumption. Adverse effects during combined therapy were minor and tolerable. Thus patients limited by exertional angina despite beta-adrenergic-blocking drugs may obtain supplemental relief of angina and myocardial ischemia with the addition of nisoldipine in a dose of 10 mg daily.

Diltiazem and propranolol combination for the treatment of chronic stable angina pectoris

To examine the benefits and risks of combined diltiazem and propranolol therapy, 23 patients who had completed a double-blind placebo-controlled cross-over comparison between diltiazem and propranolol and who continued to develop angina despite treatment were studied. The patients received the previous dose of diltiazem (180 or 360 mg/day) combined with propranolol 120 mg daily for 4 weeks and if they still developed angina on exercise testing, they went on to propranolol 240 mg daily for a further 4 weeks. Efficacy and safety were evaluated by computer-assisted maximal treadmill tests, ambulatory heart rate monitoring, and resting systolic time intervals at the end of each 4-week treatment period. Low-dose combination therapy abolished treadmill angina in 6 patients, but 2 patients had to be withdrawn. The high-dose combination abolished treadmill angina in 5 of 15 patients. The exercise time and 1-mm ST depression time increased with each increment of combination therapy in patients on both doses of diltiazem. The resting, maximal, and ambulatory heart rates progressively decreased with each increment of combined therapy. Left ventricular function, as evaluated clinically and by the systolic time intervals, was not impaired, but severe sinus bradycardia (heart rate less than 40 beats/min) appeared in 3 patients. Two died during 6 months of follow-up. Only 11 of the 23 patients completed 6 months of combined therapy without an adverse reaction. Although combined diltiazem and propranolol therapy relieved angina and increased exercise tolerance in patients refractory to single drug therapy, it should be used with caution in such patients, since bradycardia can pose serious problems.

Interaction between two calcium antagonists and two beta blockers in conscious rabbits: hemodynamic consequences of differing cardiodepressant properties

The interaction between beta-adrenoreceptor blockers and calcium antagonists may occasionally be dangerous. The effects of the new calcium antagonist PN 200-110 (isradipine) were compared with those of verapamil in 3 groups of conscious rabbits pretreated with either pindolol 0.3 mg/kg, propranolol 1 mg/kg intravenously or placebo. Each animal received PN 200-110 (0.01, 0.03 and 0.1 mg/kg) and 2 or more days later verapamil (0.1, 0.3 and 1 mg/kg). The calcium antagonists were given to lower mean blood pressure to the same extent as in the placebo group. This blood pressure effect remained unchanged after pretreatment with pindolol or propranolol. Both PIN 200-110 and verapamil increased heart rate to the same extent as in the placebo group. Both beta blockers blunted the effect of PN 200-110 on heart rate but converted the verapamil-induced tachycardia to bradycardia. Propranolol blunted the PN 200-110-induced increase in cardiac output and total peripheral conductance, whereas the high verapamil dose decreased cardiac output and caused peripheral vasoconstriction in propranolol-pretreated animals. Thus, both agents lowered blood pressure by peripheral vasodilatation in the placebo group, after beta blockade; however, the mechanism of the verapamil-induced blood pressure decrease changed from pure vasodilation to a decrease in cardiac output, i.e., cardiac depression. Verapamil but not PN 200-110 prolonged the PQ interval, especially in animals who had received beta blockade. Most differences in the interaction were attributable to differences between the 2 calcium antagonists; the differences between the beta blockers were small and in favor of pindolol.

New therapeutic modalities for the treatment of elderly patients with ischemic heart disease

In developing a treatment plan for elderly patients with ischemic heart disease, it is important to appreciate that the pathophysiologic process and aging influence the type of response produced by various drugs. The aging process also alters the way drugs are absorbed, distributed, and eliminated. Each of these variables must be considered in deciding which drugs should be used and how they should be administered.

Hypotension and sinus arrest with exercise-induced hyperkalemia and combined verapamil/propranolol therapy

A case of life-threatening hypotension due to sinus arrest is described in a patient in whom exercise-induced hyperkalemia developed during a stable regimen that included verapamil, propranolol, and ibuprofen. Renal and extrarenal handling of the endogenous potassium load induced by heat and exertion in this patient may have been compromised by the presence of ibuprofen and propranolol. When superimposed upon the negative chronotropic effects of verapamil and propranolol, the hyperkalemia precipitated sinus arrest. Clinicians should be aware of this potential metabolic-drug interaction in patients taking verapamil and/or propranolol who perform strenuous exercise in hot weather or who may be exposed to other hyperkalemic precipitants.

Treatment of angina pectoris with nifedipine and atenolol: efficacy and effect on cardiac function

The antianginal effects of nifedipine 20 mg three times a day and atenolol 100 mg once a day singly and in combination were investigated in 16 patients with angina pectoris. The amount of work that could be done before angina and ST depression appeared was significantly increased by atenolol and the combination but not by nifedipine. At peak exercise the number of leads on a 16 point precordial electrocardiogram map that demonstrated greater than or equal to 1 mm ST segment depression was significantly reduced from a mean (SD) of 5.0 (0.4) on placebo to 3.7 (0.6), 2.8 (0.4), and 2.3 (0.7) on nifedipine, atenolol, and the combination respectively. Mean resting left ventricular ejection fraction, assessed by gated radionuclide ventriculography, did not change during any active treatment phase but increased significantly during exercise only on nifedipine and the combination. The nifedipine/atenolol combination was the most effective treatment, and the data suggest that nifedipine may be used to best advantage in combination with a beta blocker.

Lidoflazine and propranolol combination treatment in chronic stable angina

The short-term (1 month) and long-term (6 months) safety of combination lidoflazine-propranolol therapy was investigated in an open trial of 15 patients with stable angina of effort. The possible advantages of adding lidoflazine (titrated to 360 mg daily) to patients having a therapeutic response to propranolol (80-400 mg daily) was also evaluated. Effects on non-invasive indexes of left ventricular function (echocardiography, systolic time intervals, radionuclide ventriculography) and exercise tolerance (treadmill exercise testing) were determined. There was no change in mean resting heart rate with the combination therapy, although one patient developed sinus bradycardia at a rate of 44 and had to have his propranolol dose reduced. Electrocardiographic analysis showed significant prolongation of the QTc intervals on lidoflazine-propranolol therapy compared to propranolol alone, with 3 patients having QTc interval prolongation to above .53 seconds, but there was no evidence of increased arrhythmogenesis with the combination therapy compared to propranolol alone. Left ventricular end-diastolic volume index tended to rise with combination therapy. However, lidoflazine-propranolol therapy did not produce any significant effects on resting ejection fraction determined by M-mode echocardiography or by radionuclide ventriculography. Radionuclide ventriculography determined peak exercise ejection fractions were also not significantly changed with combination therapy compared to propranolol alone. There were only small, insignificant improvements in exercise tolerance with the lidoflazine-propranolol combination treatment compared to propranolol alone. It is concluded that lidoflazine-propranolol combination therapy is generally safe but has the potential of causing serious adverse effects in certain patients, i.e. those with sick sinus disease, prolonged QTc intervals, and severe baseline left ventricular dysfunction, and that caution must be exercised in its use. Furthermore, it would appear that combination therapy provides only slight, if any, improvements in exercise tolerance in patients with chronic stable angina having a therapeutic response to oral propranolol.

Combination propranolol and bepridil therapy in stable angina pectoris

The safety and efficacy of bepridil plus propranolol therapy were investigated in a placebo-controlled, parallel-design, double-blind trial in 56 patients who were not responding to propranolol alone. Patients entering the study were receiving an average propranolol dosage of 131 mg/day (range 20 to 240). For the first 2 weeks of the study they were given placebo in addition to their propranolol dose, and then were randomized to receive continued placebo plus propranolol or bepridil plus propranolol therapy. The bepridil dosage was adjusted over the 8 weeks of active treatment to an average of 273 mg/day (range 200 to 400). The double-blind treatment period was followed by a 3-week washout period during which all patients received propranolol and placebo. The effects of treatment on the frequency of angina attacks, nitroglycerin consumption, exercise performance (treadmill-modified Bruce protocol) and Holter electrocardiogram (ECG) were assessed. Propranolol and bepridil plasma levels also were obtained. Improved antianginal efficacy and reduced nitroglycerin consumption were noted when bepridil was added to propranolol (p less than 0.01). During 8 weeks of combination treatment, exercise tolerance increased 1.0 +/- 1.2 minutes from a baseline of 7.3 +/- 2.2 with bepridil plus propranolol compared with an increase of 0.02 +/- 1.3 minutes from a baseline of 7.6 +/- 2.9 with placebo plus propranolol (p less than 0.01). With bepridil plus propranolol, there were also increases in exercise time to onset of angina (p less than 0.04), exercise time to 1-mm electrocardiographic ST-segment depression (p less than 0.06) and total work (p less than 0.03) compared with placebo plus propranolol therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Tolerability of combined treatment with verapamil and beta-blockers in angina resistant to monotherapy

We have used a combination of a beta-blocker and verapamil to treat 42 consecutive patients with angina resistant to either agent alone. Patients with heart failure, heart block or uncontrolled hypertension were excluded. The mean duration of follow-up was 6.5 months. Thirty-six patients (81%) reported an improvement and the number of angina attacks was reduced from 17/week to 5/week. Side effects necessitated withdrawal of one or both drugs in 6 patients, 2 of whom developed bradyarrhythmias not solely related to drug treatment. The most common complication was mild left ventricular failure (6) treated by reducing or stopping the beta-blocker. The data suggest that the combination of verapamil and a beta-blocker may be used in a relatively unselected group of patients with difficult angina. However, as dosage adjustment and close observation may be necessary to minimise side effects, the use of this combination should be limited to hospital practice.

Calcium antagonists--drug interactions

Evaluations of drug interactions should be done with caution. One needs to be aware of the reported interactions and apply the information on an individual basis. This review may therefore serve as a guide to the more common drug interactions and when drug therapy should be monitored closely in clinical practice. Major drug interactions with calcium antagonists are summarized in Table 2.

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.

Probable adverse interaction between oral metoprolol and verapamil

A combination of an oral beta-adrenergic blocking agent and verapamil has been advocated as a safe treatment for angina. A case of Wenckebach type atrioventricular block occurring in a patient on metoprolol and verapamil is reported. It is suggested that this combination is used with caution.

Hemodynamic effects of antiarrhythmic drugs

In order to use antiarrhythmic drugs safely, one must understand their hemodynamic effects. Quinidine and the calcium antagonists have direct cardiac effects and frequently opposing autonomically mediated or indirect cardiac effects. Lidocaine is exceptionally well tolerated, even by patients with severe left ventricular dysfunction. Phenytoin and procainamide have the potential for serious adverse effects, but are generally well tolerated at usual doses. Disopyramide causes serious depression of left ventricular function in many patients because of its direct myocardial depressant and peripheral vasoconstricting actions. Although bretylium causes an immediate increase in contractility, it can ultimately result in important hypotension. In this review the in vitro and in vivo hemodynamic effects of these and other antiarrhythmic drugs are discussed to provide information that will assist the clinician in using these drugs properly.

The calcium channel blockers: pharmacology and clinical applications

The calcium channel blockers provide an exciting and effective new therapeutic tool in the management of ischaemic cardiac syndromes and may prove popular and effective in the treatment of a variety of other disorders. They have provided a new approach to treatment and have added new insights into the pathogenesis of ischaemic cardiac syndromes. Their introduction into clinical practice has been swift and many of our concepts regarding their pharmacologic activities in man remain based on theoretic considerations. Their expanding clinical use and further comparative studies will undoubtedly provide further information in regard to indications, adverse effects, drug interaction and long-term safety. Particular caution is advised when they are combined with certain antiarrhythmic agents, digitalis and particularly beta adrenergic blocking agents. Little is known about their interaction with various general anaesthetic agents and for this reason particular vigilance is required as more patients receiving these agents are admitted for surgical procedures.

Long-term effectiveness of verapamil in stable and unstable angina pectoris. One-year follow-up of patients treated in placebo-controlled double-blind randomized clinical trials

The clinical responses to 12 months' treatment with verapamil were evaluated in 63 patients with stable and unstable angina pectoris in whom the effectiveness of verapamil had been established in short-term double-blind placebo-controlled randomized clinical trials. In 41 patients with effort-related angina, long-term responses were sustained for periods exceeding 1 year. Twenty patients were evaluated by clinical history and showed a sustained reduction in frequency of anginal attacks and consumption of nitroglycerin with verapamil compared with the initial placebo control periods; the magnitude of this benefit was similar to that observed during double-blind treatment with the drug. Twenty-one patients were evaluated by serial treadmill exercise testing and showed a sustained improvement in exercise duration after 4, 8, 16, 24, and 52 weeks of verapamil treatment; withdrawal of the drug resulted in a deterioration of exercise performance to levels similar to those seen before initiation of therapy. In 22 patients with unstable angina at rest, verapamil produced an amelioration of anginal symptoms that was sustained in most patients for longer than 1 year. However, these patients continued to have a high incidence of death and myocardial infarction in a frequency similar to that previously reported in large clinical studies using either combinations of verapamil and nitrates, nifedipine and propranolol, or propranolol and nitrates. Calcium-channel antagonists may decrease the number of patients requiring coronary artery bypass surgery for relief of refractory angina, but they do not appear to alter the natural history of the disease.