Everyone knows that high cholesterol levels are an important risk factor for heart disease, so it is not surprising that most of the patients I see take one or more drugs to treat their cholesterol levels. Recently, a study called ENHANCE that compared two different treatment strategies (Vytorin versus Zocor) for high cholesterol levels was published -- I didn't have to read the study to know about it, because as soon as it made the news I started getting calls from concerned patients who wanted to know what it meant for them. I researched the study and got on the phone to my patients with my recommendations.

This isn't uncommon. Announcements like these can cause a lot of anxiety for patients and physicians alike, the dramatic situation when Vioxx was removed from the market being an extreme example. My patients often ask me why new information like this comes to light after a drug is already on the market, and how they should react when they hear about drugs they are taking in the news. So let's talk about this.

Drugs are brought to market by pharmaceutical companies in the United States through a process that is regulated by the Food and Drug Administration, or FDA. The approval process has three rigorous phases that are designed to assess the safety and efficacy of new drugs before they can be prescribed and sold to patients. Efficacy can mean either that the new drug is better than no treatment at all, or that the drug is equivalent or superior to a standard therapy.

These seem to be pretty straightfoward distinctions, and sometimes they are. However, sometimes when there are many different drugs available to treat the same problem (as is the case for high cholesterol or hypertension) a new drug cannot be compared to all existing drugs during the FDA evaluation process.

In addition, the FDA often cannot fully assess the long-term consequences of drug therapies. In the case of cholesterol drugs, the FDA has historically focused on lowering cholesterol levels when determining efficacy, but the reason we want to reduce cholesterol levels is to reduce the likelihood of heart disease. The FDA has allowed most cholesterol medications to be sold and prescribed without clear evidence that they are effective in reducing heart disease, and these long-term issues get addressed, if at all, long after the drugs are approved by the FDA. The same is true for many other classes of drugs, by the way, including drugs for diabetes, hypertension and other common problems.

Safety is the other critical consideration by the FDA. There are fairly standard safety issues that the FDA considers. There is always concern about toxic effects to the liver and kidneys, for example.

Some classes of drugs have predictable side effects that get careful scrutiny based on how they work or what is known from animal studies. But sometimes drugs have unpredictable side effects. Vioxx is a case in point, and it was only after this drug had been widely prescribed that concerns about adverse effects on the heart were raised.

So how should someone react when a medicine they are taking is in the news? First, don't panic. Keep in mind that medical studies are often much more complicated than they appear in the news, and often subtle aspects of the studies can be overlooked. For example, there may be other studies that come to different conclusions than what is in the news at the moment. Second, look to authoritative sources for a reaction. In the case of the ENHANCE study, the American Heart Association published a reaction to the study for patients on their web site.

Most importantly though, don't change or stop a medicine until you discuss the news with your physician or health care provider. Physicians know to make themselves available when drugs they prescribe are in the news, and a one-on-one discussion is usually the best way to understand how the news affects your therapy and whether any changes in medication are warranted.

In the case of the ENHANCE study, I have told patients taking Vytorin that there is no reason to stop taking the drug, since the study confirmed its safety, but that in the long term it may be better to know you are on a drug with a proven benefit in reducing heart disease. Your health care provider is almost always the best resource for understanding how news about medicines applies to your own circumstances.