Drugs used in treating hyperlipidaemia fall into a number of classes:
The drugs most effective at reducing cholesterol are the statins. They work by inhibiting the enzyme HMG-CoA reductase (hydroxymethylglutaryl- coenzyme-A reductase) that catalyses the rate-limiting step in cholesterol synthesis. An effective dose of statin should reduce total cholesterol below 5 mmol/L, and thereby reduce cardivascular disease risk by about one-third. The cost is about $200-$1200 per year, depending on dosage. The benefit is great for those who have high risk. A reduction in 5-year risk from 30% to 20% is much more significant than a reduction in risk from 3% to 2%. The reason is apparent if you consider the opposite of risk -- disease-free survival. In the first case, survival improves from 70% to 80%, a worthwhile gain. In the second, it improves from 97% to 98%, a change barely worth making.
The most significant side effect of statins is muscle inflammation (severe in perhaps 1 in 1000 users) and liver damage (less frequent). Treatment should be monitored with blood tests about one week after any increase in dosage, and about every 3 months when a steady dosage is established. The major symptoms of side effects are aches and pains in muscles and joints.
Because of the high cost of some statins, the New Zealand Pharmaceutical Management Agency (Pharmac) has established rules for government subsidy of these drugs that ensure that they are funded for those most likely to benefit from them. The rules require repeated blood tests showing high cholesterol and certification that diet and lifestyle change has been tried. In some circumstances a GP can certify an application for subsidy, but in some a specialist is required.
Less effective, but still helpful in some cases, are the fibrates. Sometimes they are used in combination with statins in especially severe hyperlipidaemia, and sometimes alone. Their effect on triglycerides is greater than that of the statins. Their major side effects are gastrointestinal (nausea, vomiting, diarrhoea), muscle inflammation as with the statins (but much less frequently), impotence and skin rash.
Nicotinic acid is especially useful for treating high triglycerides. Its major side effect is a feeling of heat and flushing for an hour or so after taking the tablets, and that is best controlled by working up gradually to the required dosage and/or by taking aspirin a few minutes before the nicotinic acid.