Long-acting forms may lose their effectiveness over time, so doctors generally schedule nitrate-free breaks to prevent tolerance. Some concern exists that nitrate-free periods might increase the risk for angina and adverse heart events. One large study, however, found no increased danger when patients used a nitroglycerine patch with scheduled breaks. The use of high blood pressure drugs known as ACE inhibitors may help prevent tolerance to nitrates.
Side Effects. Nitrates have many side effects, some of which can be serious.
Common side effects of nitrates include headaches, dizziness, nausea and vomiting, blurred vision, fast heartbeat, sweating, and flushing on the face and neck. Low blood pressure and dizziness can be relieved by lying down with the legs elevated. These effects are significantly worsened by alcohol, beta-blockers, calcium channel blockers, sildenafil (Viagra), and certain antidepressants. The doctor may prescribe medicines to lessen these side effects. Patients should contact their doctor if these side effects are persistent or severe.
Serious side effects requiring immediate medical help include fever, joint or chest pain, sore throat, skin rash (especially on the face), unusual bleeding or bruising, weight gain, and swelling of the ankles.
Withdrawal. Withdrawal from nitrates should be gradual. Abrupt termination may cause angina attacks.
Beta-Blockers
Beta-blockers are useful for preventing angina attacks and reducing high blood pressure. They reduce the heart's oxygen demand by slowing the heart rate and lowering blood pressure. They are recognized for reducing deaths from heart disease and from heart surgeries, including angiography and coronary bypass. Beta-blockers are the drugs of choice for older patients with stable angina and may also be beneficial for people with silent ischemia. They are, however, less useful for the treatment of Prinzmetal’s angina. Beta-blockers are often prescribed along with other drugs such as nitrates, calcium channel blockers, or statins. A 2006 study suggested that beta-blockers and statins may help stabilize coronary artery disease and prevent the development of heart attacks.
Specific Beta-blockers. Beta-blockers include propranolol (Inderal), carvedilol (Coreg), bisoprolol (Zebeta), acebutolol (Sectral), atenolol (Tenormin), labetalol (Normodyne, Trandate), metoprolol (Lopressor, Toprol-XL), and esmolol (Brevibloc). A nasal spray form of propranolol appears to be very helpful in reducing exercise-induced angina attacks.
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