In this essay we will discuss about the drugs used for the treatment of angina pectoris:- 1. Lipid Lowering Drugs 2. Antiplatelet Drugs 3. Anticoagulant Drugs 4. ACE Inhibitors 5. Nitrates 6. β Blockers 7. Calcium Channel Blockers.
1. Lipid Lowering Drugs:
Statins in patients with elevated baseline total cholesterol levels reduce the risk of unstable angina, MI and even the need of revascularisation. Simvasatin in fixed doses of 40 mg/day, in patients with increased risk of coronary death because of prior MI, coronary artery disease or peripheral vascular disease, diabetes mellitus, treated hypertension or age 40 to 80 years with a total cholesterol greater than 135 mg/dl, has been reported to reduce the risk of MI, stroke, and revascularisation by one third regardless of cholesterol and LDL cholesterol levels at base line, age, sex or other treatments.
2. Antiplatelet Drugs:
Aspirin (325 mg every other day) in patients with stable angina has been shown to reduce cardiovascular events (MI) by 33% and is considered as a first-line agent in all patients with coronary artery disease and other vascular disease. Aspirin is also effective in primary prevention in patients without known coronary artery disease.
Clopidogrel (75 mg/day), though not so effective in primary prevention of risk factors, is at least as effective in secondary prevention in patients with an acute coronary syndrome and can be used as an alternative in patients who are allergic or intolerant to aspirin. Clopidogrel is associated with fewer gastrointestinal side effects, slightly more cutaneous reactions, and no excess total bleeding. There was no excess leucopenia or thrombocytopenia with clopidogrel compared with aspirin. The combination of aspirin and clopidogrel is used in selected patients at high risk.
3. Anticoagulant Drugs:
Warfarin is as effective as aspirin for secondary prevention but is associated with a higher risk of bleeding. Combination therapy with warfarin plus aspirin is superior to aspirin alone, provided that INR is maintained greater than 2.0, though the risk of bleeding has to be kept in mind. Warfarin is indicated in patients with atrial fibrillation and in patients with left ventricular mural thrombosis.
4. ACE Inhibitors:
ACE inhibitors are indicated for all patients with coronary artery disease, especially those associated with hypertension, left ventricular dysfunction or diabetes. Ramipril, 10 mg daily, has been reported to reduce the incidence of MI, stroke, or death from cardiovascular causes.
The choice of preparation depends on the acuity of patient’s symptoms. Sublingual nitroglycerin (spray or tablets, 0.4 mg every 5 minutes for a total of 3 doses) is used at the first indication of angina attack or prophylactically before engaging in activities that are known to precipitate angina.
Nitroglycerin reduces myocardial oxygen demand by reducing the preload (due to venous dilation) and afterload (due to arteriolar dilation) while enhancing myocardial oxygen delivery (due to epicardial artery dilation). Long-acting nitrates topically (transdermal nitroglycerine patches) or orally (isosorbide mononitrate SR) are used to prevent angina attacks and to improve exercise tolerance.
Nitroglycerine use is contraindicated in the presence of hypotension or if the patient has used sidenafil (Viagra) within the previous 24 hours. Nitrates generally are not used on a continuous basis because of the development of nitrate tolerance. An 8 to 12 hours free of nitrate exposure daily avoids the development of tolerance.
6. β Blockers:
β blockers are a key first choice of anti-angina therapy. All β blockers appear to be effective in controlling angina by decreasing heart rate and blood pressure. The doses are adjusted to result in a resting heart rate of 50-60 beats/minute. In patient with persistent angina, a target rate of less than 50 is warranted provided that no symptoms are associated with bradycardia and that heart block does not develop. Contraindications to β blockers are severe bronchospasm, significant atrioventricular (AV) block, marked resting bradycardia, or poorly compensated heart failure.
7. Calcium Channel Blockers:
Calcium channel blockers can be used in lieu of a β blocker, if β blockers are contraindicated or not tolerated due to significant adverse effects. Calcium antagonists can also be used in conjunction with β blockers if the latter are not fully effective at relieving angina symptoms. Long acting dihydropyridines and non-dihydropyridines agents are used.
Use of short acting dihydropyridines (e.g. nifedipine) should be avoided due to the potential to enhance the risk of adverse cardiac events. Worsening of heart failure can occur with all drugs, whereas bradycardia and atrioventricular dissociation can occur with verapamil and diltiazem, particularly when combined with β blockers.