DRUGS WHICH ARE USED TO REDUCE THE RISK OF MYOCARDIAL INFARCTION

CHOLESTEROL LOWERING DRUGS
For many years elevated plasma LDL concentration was known to increase the risk of premature coronary atherosclerosis and myocardial infarctions. So the physicians now target their treatments towards lowering of the plasma LDL and cholesterol concentration. It is also known the increased level of HDL which reduces the risk of atherosclerosis.

Statins: HMG-CoA reductase inhibitors
Major group of drugs used to reduce plasma-LDL cholesterol is Statins or HMG-CoA reductase inhibitors. These drugs reduce the lever synthesis of cholesterol by inhibiting the lever enzyme HMG-CoA reductase and thereby reduce the plasma LDL-cholesterol level. In addition to this statins increase the synthesis of LDL-receptors and increases the clearance of LDL. Simvastatin, Lovostatin, Pravastatin and Atorvastatin are few statins which are commonely used. All these drugs are well tolerated but contraindicated during pregnancy. (HMG-CoA reductase guides migrating primordial germ cells.) Several large randomized trials have shown promising effects on mortality by coronary vascular diseases.

In addition to the LDL-cholesterol lowering effect the use of statins has many other benefits,
Improved endothelial function
Reduced vascular inflammation
Increased neovascularization of ischemic tissue
Increased circulating endothelial progenitor cells.
Stabilization of atherosclerotic plaque
Antithrombotic action
Enhanced fibrinolysis
Osteoclast apoptosis and increased synthetic activity in osteoblasts


Adverse effects

Mild unwanted side effects include gastrointestinal disturbance, increased plasma concentration of liver enzymes, insomnia and rash. More serous adverse effects are rare but include severe myositis and angio-oedema.

Fibrates

This is another class of drugs used to reduce the plasma LDL, VLDL and thereby plasma triglyceride concentration. All the fibrates are fibric acid derivatives. One derivative (gemfibrozil) has shown to reduce the coronary heard disease by one third compared with the placebo.

Bile acid binding resins

Anion exchange resins like Colestrymine and colestipol are anion exchange resins. When these are taken by mouth they sequester bile acids and reduce enterohepatic circulation. This results in covertion of endogenous cholesterol to bile acids by the liver. This leads to increased expression of LDL receptors on liver cells.

ANTIPLATELET DRUGS

Antiplatelet drugs reduce the aggregation of platelets and thereby reduce the risk of thrombo-embolism. Most commonly used drug in this class is aspirin. Aspirin alters the balance between TXA2 and PGI2. Aspirin irreversibly acetylates a serine residue in the active site of the COX- 1 enzyme and thereby irreversibly inactivating it. This enzyme is require by the endothelium for the synthesis of PGI2 (Which inhibits platelet aggregation) and by the platelets for the synthesis of TXA2 (Which promotes platelet aggregation)

These drugs are used,
In acute myocardial infarction
High risk of myocardial infarction
Following coronary artery bypass grafting
Following coronary artery angioplasty
Transient cerebral ischemic attack


Keywords
Drug interaction, Anticoagulants. Ischemia, Cerebral infarction, phosphodiesterase inhibitor, Oral anticoagulant, pharmacokinetic aspects