Multiclinic comparison of labetalol to metoprolol in treatment of mild to moderate systemic hypertension

Perinatal outcomes after in-utero exposure to beta-blockers in women with heart disease: Data from the ESC EORP registry of pregnancy and cardiac disease (ROPAC)

BACKGROUND

Beta-blockers are commonly used drugs during pregnancy, especially in women with heart disease, and are regarded as relatively safe although evidence is sparse. Differences between beta-blockers are not well-studied.

METHODS

In the Registry of Pregnancy And Cardiac disease (ROPAC, n = 5739), a prospective global registry of pregnancies in women with structural heart disease, perinatal outcomes (small for gestational age (SGA), birth weight, neonatal congenital heart disease (nCHD) and perinatal mortality) were compared between women with and without beta-blocker exposure, and between different beta-blockers. Multivariable regression analysis was used for the effect of beta-blockers on birth weight, SGA and nCHD (after adjustment for maternal and perinatal confounders).

RESULTS

Beta-blockers were used in 875 (15.2%) ROPAC pregnancies, with metoprolol (n = 323, 37%) and bisoprolol (n = 261, 30%) being the most frequent. Women with beta-blocker exposure had more SGA infants (15.3% vs 9.3%, p < 0.001) and nCHD (4.7% vs 2.7%, p = 0.001). Perinatal mortality rates were not different (1.4% vs 1.9%, p = 0.272). The adjusted mean difference in birth weight was -177 g (-5.8%), the adjusted OR for SGA was 1.7 (95% CI 1.3-2.1) and for nCHD 2.3 (1.6-3.5). With metoprolol as reference, labetalol (0.2, 0.1-0.4) was the least likely to cause SGA, and atenolol (2.3, 1.1-4.9) the most.

CONCLUSIONS

In women with heart disease an association was found between maternal beta-blocker use and perinatal outcomes. Labetalol seems to be associated with the lowest risk of developing SGA, while atenolol should be avoided.

Drug Dosing in Critically Ill Patients with Renal Failure: A Pharmacokinetic Approach

Accurate pharmacotherapy management in the intensive care unit (ICU) patient is crucial to minimize adverse drug events. Pharmacokinetic principles including absorption, distribution, metabolism, and excretion (ADME) all play an important role in determining the fate of medications used in the critical care setting. Renal failure in this setting further alters pharmacokinetic parameters, resulting in drug dosing changes. This article highlights and applies principles of drug dosing in normal patients and in the pharmacokinetically challenging environment of critically ill patients with renal failure. Specific drug dosing tables serve as a guide for the clinician to renally adjust medication doses in the critically ill patient with renal failure.

Effects of beta-blockers on glucose and lipid metabolism

BACKGROUND

Activation of the sympathetic nervous system (SNS) has been linked to hypertension. Beta-blockers, which decrease SNS activation via beta-adrenergic receptor antagonism, are effective in lowering blood pressure and reducing cardiovascular morbidity and mortality in several conditions, including post-myocardial infarction and heart failure. Despite these clinical benefits, many physicians are reluctant to prescribe beta-blockers because of perceived negative metabolic effects, including reduced glycemic control, masking of hypoglycemia, insulin resistance, and dyslipidemia.

OBJECTIVE

This article reviews the pathophysiology of hypertension and either insulin resistance or dyslipidemia as well as treatment effects from glucose- and lipid-lowering regimens on cardiovascular morbidity and mortality. Based on a PubMed literature search from January 1980 to December 2008, the effects of nonvasodilating (atenolol, metoprolol, and propranolol) and vasodilating beta-blockers (carvedilol, labetalol, and nebivolol) on parameters of glucose and lipid metabolism in hypertension are presented. Preference for clinical trial inclusion was given to randomized, controlled trials with at least 100 patients. Limitations of a drug class literature review may include trial inclusion bias with associated result skewing and underrepresentation of an individual agent, which may give different results.

RESULTS

Beta-blockers differ in terms of their mechanism of action and their effects on glucose and lipid metabolism. Nonvasodilating beta-blockers reduce blood pressure in association with a cardiac output reduction and may increase or have no appreciable effect on peripheral vascular resistance. As a result, nonvasodilating beta-blockers are associated with a worsening of glycemic and lipidic control. In contrast, vasodilating beta-blockers reduce peripheral vascular resistance but have little or no effect on cardiac output. Numerous studies have established that vasodilating beta-blockers are associated with more favorable effects on glucose and lipid profiles than nonvasodilating beta-blockers.

CONCLUSIONS

Improvements in glucose and lipid metabolism mediated by vasodilating beta-blockers may help reduce coronary artery disease risk among high-risk patients with hypertension.

Hyperlipidemia

Coronary heart disease (CHD) is prevalent and often related to an unhealthy diet and hyperlipidemia. The diagnosis of hyperlipidemia should be carefully made, using more than one measurement in the manner described. An assessment of risks allows one to decide whom to treat. Patients with CHD should be treated aggressively but it is less clear how aggressive to be with patients without CHD. Diet and exercise recommendations are appropriate for almost all patients. For those for whom the benefit is greater than the potential risks, statins are first-line drug therapy and they appear to have beneficial effects aside from their lipid-lowering properties.

Antihypertensive therapy

Choosing antihypertensive agents that protect patients against cardiovascular and other complications is a growing trend in the treatment of mild to moderate hypertension. Calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors are favored because they have neutral or positive effects on lipid levels and insulin resistance. The alpha 1 blockers, especially doxazosin mesylate (Cardura), are enjoying a resurgence in popularity because they have a beneficial effect on lipid levels. In terms of preserving patients' quality of life, the ACE inhibitors in particular have been shown to have a positive impact. It has been shown that systolic hypertension in elderly patients should definitely be treated, but the most appropriate agent has yet to be defined. Therapy should be tailored to the individual. The following questions should be considered when choosing an antihypertensive agent: (1) What are its side effects (especially metabolic ones)? (2) Does it require only once- or twice-a-day dosing? (3) Does it cause regression of left ventricular hypertrophy? (4) Does it prevent death from coronary artery disease? (5) How will it affect quality of life? (6) How much does it cost? The goal of therapy should be to provide adequate blood pressure control throughout the day, enhance compliance, and protect the heart, brain, and kidneys without adversely affecting metabolic state.

Comparison of labetalol and hydrochlorothiazide in elderly patients with hypertension using 24-hour ambulatory blood pressure monitoring

The safety and efficacy of labetalol and hydrochlorothiazide (HCTZ) were compared in a group of 34 patients aged 65 years or older with mild to moderate essential hypertension. After a 4-week placebo run-in period, during which all previous antihypertensive medication was discontinued, patients were randomized to receive either labetalol (100 mg bid) or HCTZ (25 mg bid). The patients' blood pressure and heart rate were evaluated biweekly and drug dosage was titrated (up to 400 mg and 50 mg bid of labetalol and HCTZ, respectively) to achieve a standing diastolic blood pressure less than 90 mm Hg. Patients underwent 24-hour ambulatory blood pressure monitoring at the end of the placebo run-in period and again after the 6-week titration period. Both labetalol and HCTZ significantly (P less than .01) reduced standing systolic (-19.4 vs -27.7 mm Hg) and diastolic (-14.0 vs -15.2 mm Hg) blood pressures following 12 weeks of treatment. Both antihypertensives effectively controlled the 24-hour ambulatory blood pressure, however, the labetalol group experienced a significantly lower rate of rise in diastolic blood pressure (P = .02) and mean arterial pressure (P = .02) during the acceleration period (400-1200) compared to the HCTZ group. HCTZ caused significant decreases in serum potassium (P less than .01) and alkaline phosphatase (P less than .05) and increases in uric acid (P less than .01) and urea nitrogen (P = .07). These results indicate that labetalol may offer some unique advantages over thiazide diuretics that may be particularly important in the treatment of elderly patients with hypertension.

Initial drug therapy for hypertensive patients with hyperlipidemia

Hypertension and hyperlipidemia are cardiovascular risk factors that commonly coexist. Studies have indicated that it is important to control both risk factors to achieve significant reductions in morbidity and mortality. Recent debate has focused upon whether traditional step I antihypertensive agents can substantially lower these risks because of their effects on plasma lipids. This debate continues to be unresolved. However, for the patient with elevated lipid levels, diuretics and beta-blockers may make the management of the lipid disorder more difficult. Therefore it may be desirable to select alternative step I antihypertensive agents that will not interfere with the therapy for hyperlipidemia. Alternative step I agents include alpha 1-blockers, ACE inhibitors, and calcium channel blockers. These agents either have no effect on plasma lipids or they improve the lipid profile. Generally, these drugs are well tolerated and provide good alternatives for patients with hyperlipidemias. The initial drug of choice can be chosen depending upon other patient variables such as age, race, or concomitant diseases.

Treatment of hypertension in the elderly with labetalol

Elderly and young hypertensive patients differ with regard to clinical and pathophysiologic profiles. In the elderly, hypertension is generally characterized by elevated peripheral vascular resistance and decreased cardiac output. To establish an individualized or patient-specific approach to their treatment, antihypertensive agents must be evaluated specifically in this subpopulation. Labetalol, an alpha- and beta-blocking agent, has been shown to lower blood pressure in young and elderly hypertensive patients primarily by reducing peripheral vascular resistance without compromising cardiac output. Examination of recent reports on the pharmacokinetics and pharmacodynamic effects, and on the efficacy and safety of labetalol in elderly persons with hypertension, leads us to conclude that the drug appears to be well suited for use in these patients.

Labetalol compared with propranolol in patients with both angina pectoris and systemic hypertension: a double-blind study

Labetalol is a non-selective beta-adrenoceptor antagonist agent with added alpha 1-adrenergic blocking properties, beta 2-stimulating action, and direct vasodilatory activity. A multi-center, double-blind, parallel group study compared the safety and efficacy of labetalol to propranolol in the treatment of patients with both exertional angina and mild to moderate systemic hypertension. An initial 4 to 5 week placebo washout phase was followed by a five week titration phase and a four month maintenance phase. Labetalol and propranolol had similar effects in reducing supine and standing blood pressures, except for a greater reduction in standing systolic blood pressure seen in the labetalol group. There were comparable effects by both treatments on angina attacks, nitroglycerin use, and exercise tolerance. Adverse effects were frequent with both drugs, but were generally minor. Thus, labetalol appears to be an effective alternative to propranolol in the treatment of patients with coexisting angina pectoris and hypertension, with the choice of agent dependent on the clinical situation.

Labetalol. A reappraisal of its pharmacology, pharmacokinetics and therapeutic use in hypertension and ischaemic heart disease

Since labetalol was first reviewed in the Journal (1978), its scope of therapeutic use has expanded and become better defined. Labetalol is an adrenoceptor blocking drug with combined alpha- and beta-blocking properties. These result in a more favourable haemodynamic profile for labetalol compared with 'pure' beta-blockers or pure alpha-blockers, but also contribute to a wider range, but not an overall increased incidence, of adverse effects. The drug is effective and well-tolerated in patients with all grades of hypertension, but is of particular value in special subgroups such as Black patients, the elderly and patients with renal hypertension. While comparative studies are not extensive, available data show that the drug reduces blood pressure to a similar extent, and in a similar proportion of patients, as 'pure' beta-blockers such as propranolol, pure alpha-blockers such as prazosin, calcium antagonists (nifedipine, verapamil), and centrally acting drugs (clonidine and methyldopa). Labetalol is very effective in hypertensive pregnant women and in hypertensive crises, where it provides good control of blood pressure without serious adverse effects, and where few therapeutic options exist. Few controlled studies have investigated the use of labetalol in deliberate induction of hypotension or prevention of hypertension during anaesthesia, and also in patients with ischaemic heart disease. However, available evidence suggests a role for labetalol in these indications and further studies should aid in clarification of its efficacy in these areas. Thus, with its broad scope of therapeutic use in hypertension labetalol remains an important therapeutic option, and the drug may well find an additional place in the treatment of myocardial ischaemia if further evidence confirms encouraging preliminary findings.

New insights and new approaches for the treatment of essential hypertension: selection of therapy based on coronary heart disease risk factor analysis, hemodynamic profiles, quality of life, and subsets of hypertension

The pharmacologic therapy of mild primary hypertension (diastolic blood pressure less than 105 mm Hg) has effectively reduced hypertensive arteriolar end organ disease such as cerebrovascular accidents, congestive heart failure, and nephropathy, but there has been no convincing evidence that coronary heart disease (CHD) or its complications, acute myocardial infarction or angina, have been reduced. The risks of therapy with certain antihypertensive drugs may outweigh their treatment benefits as it relates to CHD. The optimal treatment strategy should be to reduce all CHD risk factors, reverse the hemodynamic abnormalities present by lowering the systemic vascular resistance (SVR), preserving cardiac output (CO) and perfusion, and to select the best antihypertensive drug for concomitant medical diseases or problems while maintaining a good quality of life. Antihypertensive drugs that have favorable or neutral effects on CHD risk factors include alpha blockers, calcium channel blockers, central alpha agonists, and angiotensin-converting enzyme inhibitors. On the other hand, diuretics and beta blockers without intrinsic sympathomimetic activity have unfavorable effects on many CHD risk factors. Baseline and serial evaluation of the effects of these drugs on serum lipids, lipid subfractions, glucose, uric acid, electrolytes, exercise tolerance, left ventricular hypertrophy, blood pressure, SVR, CO, perfusion, concomitant diseases, and side effects is necessary to evaluate overall cardiovascular risk.

The relevance of plasma lipid changes with cardiovascular drug therapy

Evidence is reviewed that thiazide diuretics increase plasma levels of triglycerides and LDL-cholesterol, and that most beta-blockers increase triglycerides and depress HDL-cholesterol. By contrast, indapamide, pindolol, and calcium channel blockers have little effect, and alpha 1-blockers and alpha 2-stimulants may improve the HDL- to LDL-cholesterol ratio.

Comparison of the metabolic effects of long-term treatment with pindolol or atenolol by hypertensive patients

The effects of plasma lipids, blood glucose, and serum total cholesterol, LDL-cholesterol, VLDL-cholesterol, 6-month period were studied in 18 patients with essential hypertension. There were no significant changes in the concentration of serum total cholesterol. LDL-cholesterol, VLDL-cholesterol, and triglycerides during treatment periods with pindolol or atenolol, although there was a tendency to higher triglyceride levels during atenolol treatment. The serum HDL-cholesterol levels were significantly lower after 6 months of therapy with atenolol than before treatment, but HDL-cholesterol levels increased slightly during pindolol treatment. The ratio of HDL-cholesterol to total cholesterol decreased significantly during 6 months of treatment with atenolol. Fasting blood glucose concentrations did not change significantly during 6 months of treatment with pindolol or atenolol, but during oral glucose tolerance test, blood glucose values at 60 min were raised after pindolol therapy. Serum insulin levels during oral glucose tolerance test at 120 min were decreased after pindolol therapy, but no significant changes were found in C-peptide levels during treatment periods.

The effects of beta-adrenergic blocking agents on blood lipid levels

This review examines the effects of beta-adrenergic blocking agents on blood lipids. These agents have been effective in the treatment of angina and hypertension and in the reduction of recurrence of ischemic cardiac disease, such as myocardial infarction. Many beta blockers, however, have an adverse effect on blood lipids, especially by reducing high-density lipoprotein (HDL) cholesterol and increasing triglycerides. One result is an unfavorable influence on the cholesterol ratio (expressed either as low-density lipoprotein [LDL]/HDL or total cholesterol/HDL). These cholesterol parameters have been shown to have a strong influence on coronary heart disease (CHD) risk. Studies have shown that antihypertensive therapy has reduced the incidence of cerebrovascular disease but, in many instances, has not reduced the incidence of CHD. A hypothesis for this lesser effect on coronary disease is that antihypertensive agents may be adversely affecting blood lipids. Thus, while one major risk factor for CHD is reduced, another may be somewhat enhanced. Pharmacologic properties of some beta blockers such as peripheral alpha blockade (e.g., with labetalol) or intrinsic sympathomimetic activity (ISA) (e.g., with pindolol) may counteract some of these negative lipid effects. An investigational beta blocker, bevantolol, which will be marketed shortly in the United States, has been effective in antihypertensive therapy. Bevantolol has been shown to lower LDL cholesterol and not adversely affect HDL cholesterol; in this way, bevantolol favorably influences the serum lipoprotein profile. Whether this effect will have clinical significance remains to be seen.

Plasma lipid lowering effects of doxazosin, a new selective alpha1 adrenergic inhibitor for systemic hypertension

Hypertension and hypercholesterolemia are 2 major risk factors for atherosclerotic coronary artery disease (CAD). Elevations of both blood pressure and serum cholesterol levels should be reduced to control CAD risk. Doxazosin is a once-daily, long-acting, selective alpha 1-adrenergic inhibitor that is effective for the treatment of essential hypertension. During controlled studies of doxazosin's antihypertensive efficacy, 3 serum lipid parameters were measured; total cholesterol, total triglyceride and high density lipoprotein (HDL) cholesterol. In 10- to 12-week placebo-controlled studies, 142 doxazosin-treated patients were compared with 155 placebo-controlled subjects. Doxazosin patients had an increase of 8.9% in the HDL/total cholesterol ratio (p less than 0.05), whereas total cholesterol, HDL cholesterol and triglyceride levels were not significantly different between the 2 study groups. During a 52-week comparison of doxazosin versus atenolol, doxazosin treatment was associated with a significant decrease in total triglyceride levels (5%; p less than 0.001) and increases in HDL cholesterol levels (3.9%; p less than 0.01) and HDL/total cholesterol ratio (5.4%; p less than 0.0001). Doxazosin is an effective antihypertensive agent that has a favorable impact on serum lipid levels, thereby promoting a beneficial effect on 2 major CAD risk factors.

Labetalol in the treatment of essential hypertension: a single-blind dose ranging study

The hypotensive efficacy of labetalol was evaluated in 29 patients with essential hypertension in a single-blind dose ranging study. After a two-week period of placebo treatment, labetalol was given in oral doses of 0.6 g/d, 0.8 g/d, and 0.8 g/d combined with 25-50 mg/d of hydrochlorothiazide. Each regimen lasted four weeks. The decrease in blood pressure was dose dependent: 90% of patients showed a significant reduction in diastolic blood pressure and 75% showed a significant reduction in systolic blood pressure. In 69% of the patients, side effects of the drug were noted, and in five patients (17%), treatment was discontinued because of the side effects. Seven patients received labetalol intravenously before the oral treatment. Their heart rate and blood pressure reductions were similar to those found in patients only taking the medication orally. We conclude that labetalol is an efficient and safe antihypertensive agent in both oral and intravenous administration. However, the high incidence of side effects makes labetalol a drug of second choice in uncomplicated hypertensive patients.

Metoprolol. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in hypertension, ischaemic heart disease and related cardiovascular disorders

During the intervening years since metoprolol was first reviewed in the Journal (1977), it has become widely used in the treatment of mild to moderate hypertension and angina pectoris. Although much data have accumulated, its precise mechanisms of action in these diseases remain largely uncertain. Optimum treatment of hypertension and angina pectoris with metoprolol is achieved through dose titration within the therapeutic range. It has been clearly demonstrated that metoprolol is at least as effective as other beta-blockers, diuretics and certain calcium antagonists in the majority of patients. Although a twice daily dosage regimen is normally used, satisfactory control can be maintained in many patients with single daily doses of conventional or, more frequently, slow release formulations. Addition of a diuretic may improve the overall response rate in hypertension. Several controlled trials have studied the effects of metoprolol administered during the acute phase and after myocardial infarction. In early intervention trials a reduction in total mortality was achieved in one moderately large trial of prolonged treatment, but in another, which excluded patients already being treated with beta-blockers or certain calcium antagonists and where treatment was only short term, mortality was significantly reduced only in 'high risk' patients. Overall results with metoprolol have not demonstrated that early intervention treatment in all patients produces clinically important improvement in short term mortality. Thus, the use of metoprolol during the early stages of myocardial infarction is controversial, largely because of the requirement to treat all patients to save a small number at 'high risk'. This blanket coverage approach to treatment may be more justified during the post-infarction follow-up phase since it has been shown that metoprolol slightly, but significantly, reduces the mortality rate for periods of up to 3 years. Metoprolol is generally well tolerated and its beta 1-selectivity may facilitate its administration to certain patients (e.g. asthmatics and diabetics) in whom non-selective beta-blockers are contraindicated. Temporary fatigue, dizziness and headache are among the most frequently reported side effects. After a decade of use, metoprolol is well established as a first choice drug in mild to moderate hypertension and stable angina, and is beneficial in post-infarction patients. Further study is needed in less well established areas of treatment such as cardiac arrhythmias, idiopathic dilated cardiomyopathy and hypertensive cardiomegaly.

Antihypertensive therapy and lipids. Paradoxical influences on cardiovascular disease risk

It is generally acknowledged that hypertension is associated with an increased risk of cardiovascular morbidity and mortality, and that lowering elevated blood pressure is effective in reducing that risk. However, hypertension is more likely to cause cardiovascular disease in those with additional risk factors, such as cigarette smoking, hyperlipidemia, diabetes mellitus, hypokalemia, loft ventricular hypertrophy, or electrocardiographic abnormalities. The evidence to date indicates that not all patients with mild hypertension need to be treated with drugs; not all of those receiving drug therapy should be treated with the same drugs; and the benefit of the same degree of reduction in blood pressure may not be equivalent for different drugs. The use of traditional step 1 diuretic therapy is not uniformly appropriate. As an alternative, the vasodilator prazosin can be effective as monotherapy in the treatment of mild hypertension, and its addition to diuretic or beta blocker therapy appears to blunt or prevent the adverse effects of those agents on lipid levels. Since prazosin therapy is least likely to worsen existing risk factors or precipitate their occurrence, it should enhance the benefit of blood pressure reduction in delaying or preventing cardiovascular disease.

Management of urgent hypertension: a comparison of oral treatment regimens in the emergency department

Urgent hypertension is defined by severe elevations of blood pressure without associated end-organ damage. The use of parenteral agents for this entity entails intensive monitoring and the potential for significant hemodynamic complications. Therefore, various oral regimens have been studied. Herein described are mechanisms of action, pharmacokinetics, clinical efficacy, and side effects of oral agents used in the treatment of urgent hypertension.

Effects of combined alpha and beta adrenoceptor blockade in patients with angina pectoris. A double blind study comparing labetalol with placebo

The effects of a combined alpha and beta receptor antagonist, labetalol, were investigated in 10 patients with chronic stable angina pectoris. The optimal dose was determined during an initial dose titration study when the patients were treated with 200 mg, 400 mg, and 600 mg (six patients) of labetalol a day. The effective dose was then compared with placebo in a double blind randomised study. The effects of the drug were monitored with angina diaries, treadmill exercise testing, and 48 hour ambulatory electrocardiographic ST segment monitoring. Plasma labetalol concentrations were measured during each treatment period. The mean effective antianginal dose of labetalol was 480 (SD 140) mg/day given by mouth twice a day. There was a dose related reduction in daytime and nocturnal heart rate, the frequency of pain was significantly reduced by 41%, and exercise duration was significantly increased by 44% with labetalol when compared with placebo. The frequency and duration of the episodes of ST segment depression were significantly reduced by 56% and 73% respectively with labetalol. Adverse effects resulted in a reduction of the dose of labetalol in two patients. Thus labetalol is an effective agent in the treatment of angina pectoris.

Alpha- and beta-blockade in angina pectoris

Angina pectoris encompasses a clinically diverse group of syndromes in which the common factor is myocardial ischaemia resulting from an imbalance between oxygen requirement and delivery. Anginal pain is most frequently precipitated by exercise, but may occur without any apparent cause at rest. Fixed obstructions in the coronary vessels, often attended by thickening of the overlying coronary artery media, are the most frequent cause of ischaemic cardiac pain. The resulting myocardial fibrosis impairs efficient filling and emptying of the ventricles, further aggravating the functional embarrassment resulting from the reduced coronary blood flow. In stable coronary heart disease the increased energy demands during exercise are associated with the rapid development of a haemodynamic profile characteristic of acute left ventricular failure. This results in further substantial increases in pressure work, wall stress and oxygen consumption of the left ventricle. The reflex sympathoadrenal consequences of these primary haemodynamic changes lead to further mechanical and electrical embarrassment of the ischaemic heart. Increased stimulation of beta 1- and beta 2-receptors in the heart increases heart rate and contractility and thereby myocardial oxygen demand. Increased stimulation of alpha-receptors in the peripheral veins and arteries indirectly increases left ventricular oxygen demand still further by increasing preload and afterload, respectively. The reduced blood flow to the endocardium enhances its sensitivity to increased sympathoadrenal stimulation and facilitates initiation of arrhythmias. Blockade of all adrenergic activity, particularly in the myocardium, coronary arteries and peripheral blood vessels should, therefore, help alleviate the myocardial ischaemia. There is a rational argument for the use of alpha-blockade in coronary heart disease, particularly in conjunction with beta-blockade. Attenuation of the risk of coronary spasm and ventricular arrhythmias and reduction of pressure work and left ventricular afterload are amongst the potential attributes of alpha-blockade. Alone, however, their utility is severely limited by the risks of hypotension and reduction in coronary perfusion pressure and reflex oxygen-wasting tachycardia. Alone, alpha-adrenoceptor antagonists have no place in the treatment of angina pectoris. beta-Adrenoceptor blocking drugs competitively inhibit catecholamines at both cardiac and peripheral vascular beta-adrenergic receptors. Their main advantage is that they reduce many of the important determinants of myocardial oxygen consumption, particularly by reducing the heart rate during exercise.(ABSTRACT TRUNCATED AT 400 WORDS)