A group of LIPID-lowering drugs used to treat primary hypercholesterolaemia – a condition in which the concentrations of LIPOPROTEINS in the blood plasma are raised, increasing the likelihood of affected individuals developing coronary heart disease. Statins act by competitively inhibiting an ENZYME called 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase. This enzyme plays a part in the synthesis of CHOLESTEROL, particularly in the LIVER. Statins are more effective than other classes of drugs in lowering body concentrations of LDL-cholesterol, but less effective than fibrates in reducing TRIGLYCERIDE concentration. Their use results in significant reductions in heart attacks (myocardial infarctions) and other adverse cardiovascular events, such as STROKE. What remains uncertain is precisely who will benefit – some suggest that everybody over the age of 50 would benefit from statins. However, this has to take into account side-effects; most serious (although rare) is severe muscle pain and weakness, while more common are mild gastrointestinal complaints such as abdominal discomfort, bloating and loose stools. Statins should be used in conjunction with other preventive measures such as weight loss, reduction in alcohol and fat consumption, taking exercise and stopping smoking. Among statin drugs available are atorvastatin, cerivastatin sodium, fluvastatin, pracastatin sodium and simvastatin. (See HEART, DISEASES OF; HYPERLIPIDAEMIA.)