Chapter 9 β-Adrenergic Receptor Blockers as Therapeutic Agents

Publisher Summary This chapter summarizes the role of β-adrenergic receptor blockers as therapeutic agents. The first β-blocker to be effective in the treatment of angina pectoris was pronethalol. Now, this drug has become one of the most widely investigated and widely used β-blocking agents. At the same time, β-blockers are being considered as anti-anginal agents; other therapeutic uses in cardiovascular diseases are also being considered in this chapter. β-blockers are also considered for use in treatment of myocardial infarction. The first clinical trial of propranololin myocardial infarction has demonstrated that β-blockers can reduce mortality in this patient population. In addition to propranolol, two new β-blockers have now been approved for use in man in the U.S. Metoprolol has been approved for use in hypertension and timolol has been approved for use in glaucoma. In other parts of the world, there are at least 17 β-blockers available for use. By definition, all β-blockers block β-adrenergic receptors. It is this action that is responsible for their efficacy in various clinical conditions. In addition to claimed benefit in asthmatic patients, cardioselective β-blockers are proposed to offer an advantage over non-selective ones in patients with peripheral circulatory insufficiency. The prolongation of the insulin-induced hypoglycemia that is observed with β-blockers is reported to be less with cardioselective β-blockers. In addition, the hypertensive response that occurs secondarily to insulin-induced hypoglycemia in the presence of β-blockade has been reported to be less severe with cardioselective than with non-selective β-blockers. In addition to their now accepted efficacy in angina, myocardial infarction, arrhythmias, and hypertension, other disease states characterized by excess sympathetic activity, such as thyrotoxicosis, have been treated with β-blockers. β-Blockers have also been reported to be useful drugs in the treatment of migraine attacks, anxiety, and tremor. β-blockers are advocated for use in conditions such as schizophrenia and mania.