In this series on cholesterol, I have talked about the effects of exercise and started talking about particular prescription drugs. In the prior column I pointed out that the reasons behind taking these drugs ultimately come down to a question of benefit. A drug may very well control your cholesterol, but if it doesn't help you live longer or prevent stroke or heart attack, then there may be no good reason to take it Ð and a lot of good reasons not to take it.

The major classes of drugs for cholesterol include cholesterol absorption inhibitors, bile acid sequestrants, fibric acid derivates, niacin products, and statins. I talked about Zetia, the cholesterol absorption inhibitor in the last column, and did not recommend taking that drug for most patients because of the lack of data. I'll talk about other drugs with the exception of statins in this column.

The bile acid sequestrants include Questran (cholestyramine), Colestid (colestipol), and WelChol (colesevelam). These agents bind bile acids in the gut causing them to be excreted in the feces. This ultimately causes a drop in LDL and a very slight bump in HDL. These agents are difficult to take because of gastrointestinal side effects such as nausea. They suffer from the same lack of clear benefit as far as mortality is concerned as Zetia does, and I cannot recommend them for most patients. Again, speak with your doctor before making a decision.

Fibric acid derivates include Tricor (fenofibrate) and Lopid (gemfibrozil). These agents are really effective for lowering TG (triglycerides) and raising HDL. They affect LDL somewhat, but not as much as the other agents discussed above. While they have beneficial effects on the cholesterol numbers, the data is lacking here as well for mortality. I cannot recommend this class of drug for most patients because of the lack of data. There are special cases where these drugs do find uses and you should speak with your doctor before making a decision.

Nicotinic acid, or niacin, is available with or without a prescription. Niacin raises HDL, lowers LDL, and lowers TG - all good things. But it has several caveats that you must pay attention to. There are two general types of niacin products; immediate release, and slow release. Immediate release niacin products seem to be safer and more effective than slow release products.

Slow release niacin products have been associated with severe liver toxicity, as have immediate release products - although to a lesser degree. Some "no-flush" products have no free nicotinic acid and therefore should be sold as "no effect" niacin.

The main factor limiting the tolerability of niacin is its profound ability to cause flushing. Having accidentally taken a niacin pill without knowing what it was, I can tell you firsthand that this effect is very uncomfortable.

Niacin must be taken in doses of 1000 - 3000 mg daily, and you should start with doses around 100 mg three times a day and work your way up slowly over several weeks to months. This will allow the body to build up a tolerance, and you will have less flushing. If you miss doses, you may have to go back down to a lower dose and start over again to build up the tolerance again.

You can take an aspirin before taking niacin, and it will help block the flushing. Taking it with meals seems to help as well. Niacin is a complicated drug to take, and many people give up on it because of the flushing. Niacin can raise blood sugar (especially in diabetics), cause acute gout, drop blood pressure, and raise homocysteine levels.

All that being said, niacin does have some mortality data in people who have already had heart attacks. It does not have clear data in people who have no evidence of heart disease. It clearly isn't for everyone, and is a poster child for the saying "just because it's natural doesn't mean it is good for you."

You must have your liver monitored carefully and you should not take niacin on your own. Serious liver damage has rarely occurred in folks taking niacin, and it is unpredictable. There is a slow-release prescription product called Niaspan that causes less flushing than immediate release niacin, has good effects on cholesterol, and affects the liver less significantly. You should still periodically monitor liver tests while taking ANY form of niacin, as just because you are tolerating it fine now does not mean you will in the future.

You can search www.theunion.com for prior articles in this series as well as other columns. Please feel free to email with questions or suggestions for future topics at nicholas.browningmd@gmail.com