*The drug prescribed will depend on the individual, the cholesterol level, other problems, and the doctor’s preferences.
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Nicotinic acid derivatives
- Nicotinic acid (niacin) has proven cholesterol-lowering effects when given in daily doses exceeding 1 gram. However, such doses cause flushing and rashes. Treatment with nicotinic acid should be supervised by a doctor, who can advise on how to increase the dosage over three or four weeks and minimise the risk of side effects.
- Besides nicotinic acid/niacin preparations, there is a nicotinic acid derivative, acipimox (Olbetam). Side effects are less of a problem with this drug, and it may well be the drug of choice if dietary and lifestyle modifications prove ineffective, although safety in long-term use has not been established.
Fibrates
- These drugs can reduce LDL cholesterol levels by as much as 18%, and at the same time raise HDL cholesterol levels.
- – Bezafibrate (Bezalip). Its primary effect is to reduce triglyceride levels. It also increases the breakdown of LDL particles, thus lowering the LDL Cholesterol level in the bloodstream.
- – Clofibrate (Atromid-S) is gradually becoming obsolete. New derivatives have proved just as effective with fewer side effects.
- – Fenofibrate (Lipanthyl) lowers VLDL and LDL cholesterol levels and raises HDL levels.
- – Gemfibrozil (Lopid) reduces VLDL and LDL cholesterol by decreasing the synthesis of VLDL in the liver. It also raises low levels of HDL cholesterol.
- – Ciprofibrate (Modalim) reduces VLDL and LDL cholesterol levels.
The drugs in this group can be used to lower blood cholesterol levels but are more usually given in cases of raised triglyceride levels. Their long-term safety, although not fully established, looks good.
Bile acid sequestrates
Soluble fibre in the diet binds acids in the gut. Some of these bile acids are then excreted and not resorbed in the large intestine as would normally be the case. Cholesterol is then diverted into making more bile acids, thus reducing cholesterol levels. Bile acid sequestrates work in much the same way, but more effectively, binding the acids and then removing them in faeces.
Two bile acid sequestrates widely available are cholestyramine (Questran) and colestipol (Colestid).They are very successful when used correctly, lowering blood LDL levels by as much as 25%, in addition to any impact diet and lifestyle changes might have on blood cholesterol levels. Many patients use them daily to keep cholesterol levels within reasonable limits. The drugs also have the advantage of being confined to the gut; they don’t enter the body.
Bile acid sequestrates can interfere with the functioning of other prescribed drugs, so you should take them at quite different times. The long-term safety of bile-acid sequestrates is well established.
Probucol (Lurselle) has a poorly understood mode of action. It increases the loss of bile acids in faeces, so its effect is similar to the sequestrates. Long-term safety of the drug is not established. It sometimes causes nausea and diarrhoea and is not recommended during pregnancy and breastfeeding.
HMG CoA Reductase Inhibitors
The full term for this group of drugs is 3-hydroxy-3-methyl-glutaryl co-enzyme A reductase inhibitors. Despite the name, the action of these drugs is quite elegant. All body cells synthesise cholesterol; if the blood cholesterol level falls, cholesterol supply to the cells is reduced and the cells try to make up the deficit by stepping up cholesterol synthesis. The cellular manufacture of cholesterol is complex, but one of the key steps is governed by an enzyme called HMG CoA reductase. Block the action of this enzyme and you can block the manufacture of cholesterol in the cells.
Some of the more common inhibitors available are simvastatin (Zocor), pravastatin (Pravachol), fluvastatin (Lescol), atorvastatin (Lipitor) and cerivatatin (Lipobay). These drugs are generally considered the gold standard of lipid lowering therapy with a good record of clinical efficacy and long-term safety.
