Effect of beta blockade with betaxolol on left ventricular systolic function in chronic stable angina pectoris and left ventricular dysfunction

Beta receptor antagonists in the treatment of heart failure

The use of beta-receptor antagonists in the treatment of heart failure is controversial. Available data do not allow general recommendations regarding their use. In dilated cardiomyopathy, several studies suggest that long-term treatment in individual patients reduces symptoms and increases exercise capacity. Short-term treatment is usually not beneficial, except in patients with ischemically induced left ventricular dysfunction. In heart failure, post myocardial infarction and in chronic ischemic heart disease, no proper long-term study has been performed to evaluate its effects. However, patients with acute myocardial infarction tolerate beta blockers, despite the presence of left ventricular dysfunction and long-term prognosis is improved. Newer agents, some with ancillary properties, such as intrinsic activity and vasodilatation, may have advantages. In the future we need a better description of the cardiac status in our patients in order to be able to select those that will respond favorably to beta-receptor antagonists. The mechanisms by which some patients improve are still obscure. Protection against receptor downregulation, restoration of receptor density, protection against cardiotoxicity of catecholamines, and improvement in ischemic systolic and diastolic left ventricular function are all possible. The fear that beta-receptor antagonists are dangerous in heart failure is in most instances not warranted, but an initial deterioration may have to be accepted in order to gain long-term beneficial effects. Ongoing studies in both idiopathic cardiomyopathy and in postinfarction failure will hopefully help us to define the use of beta-adrenoceptor antagonists in the future.

Betaxolol: a new long-acting beta 1-selective adrenergic blocker

Betaxolol (Searle, Skokie, Illinois) is a new beta 1-selective adrenergic blocker with no partial agonist action and minimal membrane stabilizing activity. Its pharmacokinetic profile is characterized by a long serum half-life and excellent oral bioavailability, with little first-pass metabolism. The mean 16-hour half-life of betaxolol has been shown to provide full 24-hour control of blood pressure and heart rate. Betaxolol has been proven to be a safe and effective antihypertensive agent, and was recently approved for clinical use in the United States for this indication.

Efficacy of betaxolol in the treatment of stable exertional angina pectoris: a dose-ranging study

To assess the efficacy of oral betaxolol in the treatment of stable exertional angina pectoris and to determine the relationship between betaxolol doses/serum concentrations and clinical/hemodynamic responses the authors studied 24 patients prior to and following stepwise administration of 5, 10, 20, 40, and 80 mg doses. The major endpoint for the study was the achievement of clinical beta blockade (heart rate 50-60 beats/min and less than or equal to 20% rise in treadmill stage I heart rate). Betaxolol produced a decrease in mean angina pectoris frequency from 6.6 +/- 1.9 episodes/week with placebo to 0.2 +/- 0.5 episode/week during clinical beta blockade (p less than 0.00005). Mean treadmill exercise time increased from 3.1 +/- 1.7 min with placebo to 7.3 +/- 2.3 min with doses sufficient to reduce angina pectoris frequency greater than or equal to 75% (p less than 0.00005) and to 8.0 +/- 2.3 min during clinical beta blockade (p less than 0.00005). The mean doses of betaxolol required to produce a greater than or equal to 75% decrease in angina pectoris frequency and clinical beta blockade were 12 +/- 5 mg (range 5-40 mg) and 28 +/- 29 mg (range 5-80 mg) respectively. Mean serum concentrations associated with these clinical endpoints were 23.8 +/- 9.7 ng/mL and 59.7 +/- 54.0 ng/mL respectively. The results indicate that betaxolol, in widely ranging doses, is highly effective in reducing angina pectoris frequency and improving exercise capacity in patients with stable exertional angina pectoris.

Double-blind comparison of once daily betaxolol versus propranolol four times daily in stable angina pectoris. Betaxolol Investigators Group

Betaxolol is a new, highly cardioselective, once-a-day beta blocker with a long half-life (mean 16 hours). The antianginal efficacy of 2 doses of betaxolol (20 and 40 mg) given once daily was evaluated and compared with propranolol (40 or 80 mg) 4 times daily. Ninety-two patients completed the 10-week double-blind trial. The resting and exercise heart rate, blood pressure and double product were similar for all treatment arms of the study during placebo treatment. Significant decreases in these measures occurred during active drug treatment when compared with placebo. No significant intergroup differences were noted at rest. Maximal exercise heart rate and double product were significantly lower during treatment with betaxolol 40 mg daily than in the propranolol 40 mg 4 times/day treatment group (p less than 0.05). All patients had chest pain and greater than or equal to 1 mm of ST-segment depression during the baseline placebo exercise test. After 10 weeks of active treatment, 55% of the patients were free of chest pain during maximal exercise (difference not significant between treatments). In the betaxolol 40 mg/day group, fewer (6 of 19; 32%) of the patients developed ST-segment depression with exercise (p less than 0.05) compared with propranolol 80 mg 4 times daily (21 of 26; 81%). Betaxolol appears to be a useful once-a-day cardioselective beta blocker for the therapy of angina pectoris.

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.

Effects of beta blockade on systolic and diastolic left ventricular function at rest and during exercise in patients with chronic stable angina pectoris

This study examined the effects of beta blockade with betaxolol, a cardioselective, lipid-soluble, beta-adrenergic-blocking agent, on rest and exercise systolic and diastolic left ventricular function in 15 patients, aged 40 to 70 years (mean = 52), with chronic stable angina pectoris. Each patient underwent three upright exercise studies at identical workloads; the first was a baseline study, the second was done 3 hours after a single oral dose, and the third was obtained after chronic therapy for 2 weeks. Beta blockade was evident by significant decreases in heart rate, systolic blood pressure, and diastolic blood pressure at rest and during exercise (p less than 0.04). Although there were no significant changes (at rest or during exercise) in mean left ventricular ejection fraction and peak filling rate, individual variations were seen after 3 hours and 2 weeks of therapy. During chronic therapy, the peak filling rate increased in three patients, decreased in five, and remained unchanged in seven. Also, discordant changes in systolic and diastolic functions were seen at rest and during exercise during both acute and chronic therapy. Thus, although acute and chronic beta blockade produces no significant changes in mean measurements of diastolic and systolic left ventricular performance, individual variations and discordant results are seen in many patients. The acute effects are generally consistent with the chronic effects, but exceptions are present.