Commonly prescribed brands:
How they are given:
What they are used for:
To increase HDL (good) cholesterol and to lower triglyceride levels
You should not be treated with them if:
You have been diagnosed with:
Possible side effects:
Indigestion, gas, bloating, diarrhea, constipation
How do fibrates work?
Fibrates activate a gene that causes the body to produce more of the two main components of HDL (good) cholesterol, which in turn increases your HDL cholesterol level. When that gene is activated, it also causes triglycerides to be broken down, lowering your triglyceride level. Triglycerides are another type of lipid that can increase your risk of heart disease if the levels are high.
How do fibrates affect my cholesterol and triglyceride levels?
Fibrates are prescribed mainly to treat high triglyceride levels (higher than 200 mg/dL). These medications can lower triglyceride levels by 20% to 50% in men and women with high triglycerides; the greatest reductions tend to occur in people with the highest levels.76-78 In some cases, fibrates can raise LDL (bad) cholesterol levels, so they are only used to treat high triglycerides in people with normal LDL cholesterol.78, 79 In people with low triglycerides (less than 150 mg/dL), fibrates actually lower LDL cholesterol.76, 77 Fibrates can also raise your HDL (good) cholesterol by 10% to 15%.77, 80 The greatest increases in HDL cholesterol are seen in people with very high triglycerides and low HDL cholesterol (less than 40 mg/dL).72 Fibrates appear to work equally well in men and women.81
Do fibrates lower my risk of heart disease and heart attacks?
A combined analysis of 17 fibrate studies that included nearly 30,000 men and women did not find that fibrates reduced the risk of dying early.73 This analysis included an older drug, clofibrate, that was actually shown to increase the risk of dying from non-heart-related causes (including cancer) in a large study in men.82 This drug is no longer prescribed, and subsequent studies of the other fibrates did not show a higher risk of dying from any cause.
Fibrates appear to lower the risk of experiencing heart problems including heart attack although there is not a lot of information on women. In studies in men with heart disease or high cholesterol, gemfibrozil reduced the risk of dying or having a heart attack by 22% to 34%.82-84 One large study that included both women and men found that, overall, the combination of fibrates and niacin reduced the risk of the risk of dying early by 26%.85 However, the results were not analyzed separately for men and women, so it is unclear whether women experience the same benefits from fibrates that men do.
Why do I need to take a fibrate and a statin?
Fibrates are not very effective at lowering LDL cholesterol and have even been shown to raise LDL cholesterol in some people. To counteract this, your healthcare provider may prescribe a statin in addition to a fibrate. This combination is used in people with high LDL cholesterol, low HDL cholesterol, and high triglycerides. Several studies have shown that this combination improves cholesterol and triglyceride levels in men and women.86-89 The lipid improvements are greater than those seen with a statin or fibrate alone.90-92 It is not yet known if combined statin/fibrate treatment will lower the risk of having a heart attack or dying from heart disease. Combining fibrates and statins increases the risks for certain serious side effects (see below).
What are the major risks of fibrate therapy?
Fibrates have been associated with an increased risk of developing muscle weakness ( myopathy). In rare cases, myopathy can develop into rhabdomyolysis, a potentially fatal condition in which muscle cells break down and release their contents into the bloodstream. Signs of rhabdomyolysis include muscle pain, swelling, or weakness, usually affecting the back or lower calves. Fever, nausea, dark urine, and a general feeling of discomfort may also occur. If you are taking fibrates and experience any of these symptoms, you should contact your healthcare provider immediately. The risk of both of these conditions increases when you take fibrates in addition to a statin. Women have a higher risk of myopathy than men when using both fibrates and statins.93 Gemfibrozil carries a higher risk of triggering rhabdomyolysis than fenofibrate (see Gemfibrozil versus fenofibrate).94, 95
Fibrates may cause liver problems; your healthcare provider will run blood tests before you take these medications and repeat them intermittently. If the blood tests show signs of liver damage, you will be taken off the fibrate, and this usually resolves the problem. Fibrates may also cause gallstones.96, 97
Gemfibrozil versus fenofibrate
The risk of the potentially fatal side effect rhabdomyolysis is higher for gemfibrozil (Lopid) compared with fenofibrate (Tricor or Lofibra), particularly when combined with statins. This is because gemfibrozil appears to increase the levels of statins found in the blood,98-102 whereas fenofibrate has little or no effect on the blood levels of statins.103, 104
There are no large studies comparing fenofibrate and gemfibrozil; however, there is some evidence that fenofibrate is more effective at lowering triglycerides and LDL cholesterol, and raising HDL cholesterol.105-107 Fenofibrate was released in the US in 1998 and so far there are no studies showing it can reduce the risk of dying or having a heart attack.