Labetalol in the treatment of angina pectoris.

The present review shows that labetalol has many advantageous properties in the treatment of patients suffering from angina pectoris with or without hypertension. These patients respond with vasoconstriction to a variety of internal and external influences. The selective alpha 1-blocking component in addition to the non-selective beta-blockade of labetalol attenuates the increased coronary vascular resistance and improves coronary haemodynamics especially under stress in a manner which should be favourable in myocardial ischaemia. In addition, the alpha 1-blocking component may prevent different kinds of arrhythmias generated by alpha-adrenoceptor stimulation. Labetalol has no effect on renal blood flow, glomerular filtration rate, plasma electrolyte concentrations, glucose tolerance, lipoprotein cholesterol ratio, renin-angiotensin-aldosterone system, uric acid levels, or on platelet aggregation. Intravenously administrated labetalol has proved to be effective in patients with acute myocardial infarction, especially if associated with hypertension. In order to avoid postural hypotension, oral treatment should be started with a low dose of 100 mg twice daily. The usual dosage in patients without hypertension is 200 mg twice daily, but in patients with hypertension doses up to 1200 mg or even more have been used. In low doses up to 400 mg daily, the unwanted effects are few and often self-limited. High doses can cause side effects related to both beta- and alpha-blocking properties of labetalol. As an antianginal agent labetalol has proved to be at least as effective as selective or non-selective beta-blockers.