VII. DRUG TREATMENT
In patients with stable angina treatment with drugs usually produces about a 75% improvement in symptoms and quality of life. Three groups of drugs are usually employed: nitrates, beta-blockers, and calcium blockers (calcium antagonists). Aspirin is added to prevent coronary throm¬bosis which causes heart attacks.
A. Nitrates
Angina sufferers are advised by their doctor to always carry nitroglycerin, even if the requirement is only two pills a year. Nitroglycerin is a nitrate that is used under the tongue or in tablet or spray form. The tablets should be kept in a dark bottle and not in a pill box, because opening the box lets in light, which will destroy the effectiveness of the drug within a few weeks. Remove the cotton wool from the bottle so the pills can be easily reached when in a hurry. Leave the cotton wool in a stock bottle kept in the refrigerator; these tablets will maintain their strength for more than one year. Tablets in a bottle that is opened often should be good for three months.
1. Mechanism of Action
Nitroglycerin dilates the veins, especially those in the lower half of the body. Blood stays in these enlarged veins and less blood reaches the heart. The heart then has less blood to pump and the muscle works less, thus requiring less oxygen, and, as a result, the pain is relieved. The mechanism of action of nitrates and nitrate tolerance is illustrated in Fig. 5.
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