Antianginal and Peripheral Dilating Drugs

Vasodilating drags sometimes relieve die symptoms of vascular disease, but in some cases dragtherapy provides only minimal and temporary relief. Many of die vasodilating drug s are also used to treat hypertension. Their use as antihypertensives is discussed in Chapter 42. 

The nitrates, such as isosorbide (Isordil) and nitroglycerin, have a direct relaxing effect on die smooth muscle layer of blood vessels. The result of diis effect is an increase in the lumen of die artery or arteriole and an increase in the amount of blood flowing through diese vessels. An increased blood flow results in an increase in die oxygen supply to surrounding tissues. 

Systemic and coronary arteries are influenced by movement of calcium across cell membranes of vascular smooth muscle. The contractions of cardiac and vascular smooth muscle depend on movement of extracellular calcium ions into these walls through specific ion channels. Calcium channel blockers, such as amlodipine (Norvasc), diltiazem (Cardizem), nicardipine (Cardene), nifedipine (Procardia), and verapamil (Calan), inhibit die movement of calcium ions across cell membranes. This results in less calcium available for the transmission of nerve impulses (Fig. 41-1). This drug action of the calcium channel blockers (also known as slow channel blockers) has several effects on die heart, including an effect on die smooth muscle of arteries and arterioles. These drug dilate coronary arteries and arterioles, which in turn deliver more oxygen to cardiac muscle. Dilation of peripheral arteries reduces die workload of die heart. The end effect of these drug is the same as that of die nitrates. 

FIGURE 41 -1. Calcium channel blockers inhibit the movement of caldum ions across the cell membrane. When calcium channels are blocked by drug molecules, musde contraction is decreased, causing the smooth musdes of the arteries and arterioles to dilate. 

The nitrate antianginal drug all have the same adverse reactions, although the intensify of some reactions may vary with the drug and the dose. A common adverse reaction seen with diese drug is headache, especially early in therapy. Hypotension, dizziness, vertigo, and weakness may also be associated with headache. Flushing caused by dilatation of small capillaries near the surface of the skin may also be seen. 

This chapter discusses two different tyjDes of dru whose primary purpose is to increase blood supply to an area by dilating blood vessels the antianginal and IDeripheral vasodilating drugs. Vasodilating dni relax die smoodi muscle layer of arterial blood vessels, which results in vasodilatation, an increase in die size of blood vessels, primarily small arteries and arterioles. Because peripheral, cerebral, or coronary artery disease usually results in decreased blood flow to an area, dni diat dilate narrowed arterial blood vessels will carry more blood, followed by an increase in blood flow to the affected area Increasing die blood flow to an area may r ult in complete or partial relief of symptoms. 

The nitrates are available in various forms (, sublingual, transmucosal, translingual spray, and inhalation). Some adverse reactions are a result of the mediod of administration. For example, sublingual nitro ycerin may cause a local burning or tingling in the oral cavity. However, die patient must be aware that an absence of this effect do not indicate a decrease in the drug s potency. Contact dermatitis may occur from use of die transdermal delivery system. 

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