Angina beta-blocking drugs

Alpha-adrenergic antagonists are used primarily as antihypertensive drugs because of their ability to block vascular alpha-1 receptors. Beta-adrenergic antagonists (beta blockers) are administered primarily for their inhibitory effects on myocardial function and are used in the prevention and treatment of hypertension, angina pectoris, arrhythmias, and myocardial reinfarction. Many of the drugs introduced in this chapter are discussed further in chapters that deal with the specific clinical conditions (e.g., hypertension, asthma, and other disorders). 

Beta blockers bind to beta-1 receptors on the myocardium and block the effects of norepinephrine and epinephrine (see Chapter 20). These drugs therefore normalize sympathetic stimulation of the heart and help reduce heart rate (negative chronotropic effect) and myocardial contraction force (negative inotropic effect). Beta blockers may also prevent angina by stabilizing cardiac workload, and they may prevent certain arrhythmias by stabilizing heart rate.40 These additional properties can be useful to patients with heart failure who also have other cardiac symptoms. 

Use of Hormones in Nonendocrine Disease. There are many examples of how various hormones and hormone-related drugs can be used to treat conditions that are not directly related to the endocrine system. For instance, certain forms of cancer respond to treatment with glucocorticoids (see Chapter 36). Drugs that block the cardiac beta-1 receptors may help control angina and hypertension by preventing excessive stimulation from adrenal medulla hormones (epinephrine, norepinephrine see Chapters 21 and 22). 

Reduce the workload of the heart by blocking the sympathetic conductance at the beta receptors on the SA node and myocardial cells, thus decreasing the force of contraction and causing a reduction in heart rate Indications Hypertension, angina, arrhythmias, glaucoma, myocardial infarction, migraine prophylaxis Common drug examples ... 

The first successful drug of this type, a betorblocher, was propranolol (Inderal), now used to treat cardiac arrhythmias, angina, and hypertension. Look back at Section 17.5 to see its similarity in structure to the compounds whose action it blocks. Propranolol and the other beta-blockers have become widely prescribed drugs. 

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