According to the FDA's safety maverick, David Graham, there are at least five approved drugs out there that are unsafe and should probably be pulled from the market. Roche's Accutane, AstraZeneca's Crestor, GSK's Serevent, Pfizer's Bextra and Abbott's Meridia are all on his chopping block.

Well, Graham may not feel that he has enough power at the FDA, but he sure swings some weight in the stock market. All these companies lost several per cent of their market value on Friday, taking the whole drug sector with them. What everyone wants to know is: are these drugs safe?

What a useless question. I mean it - we're never going to get anywhere with that line of thinking. "Safe" is a word that means different things to different people at different times, which is something you'd think any adult would be able to understand. The only definition that everyone would recognize, at least in part, is "presenting no risk of any kind to anyone." That'll stand as a good trial-lawyer definition, at any rate.

And by that one, not one single drug sold today is safe. Of course they aren't. These compounds do things to your body - that's why you take them - and that's inherently risky. I don't think that I'm alone in the drug industry as someone who never takes even OTC medication unless I feel that the benefits outweigh the risks, and the risks are never zero. I know too much biochemistry to mess around with mine lightly.

The drug industry, the FDA, physicians and most patients recognize that safety standards vary depending on the severity of the disease. Toxic drug profiles are tolerated in oncology, for example, that would have stopped development of compounds in almost other area. And the standards go up as additional drugs enter a market - yes, I'm talking about those evil profit-spinning me-toos. One of the best ways to differentiate a new drug in a category is through a better safety profile.

So when someone asks, "Is drug X safe?", they're really asking a whole list of questions. What are the risks of taking the compound? That is, how severe are the side effects, and how often do they occur? How do those stack up against the benefits of the drug? Then you ask the same set of questions in each patient population for which you have distinguishable answers.

To pick an example from Graham's list, Accutane has big, dark, unmissable warnings all over it about not taking the drug while pregnant or while it's possible to become pregnant. Has that stopped people? Not enough of them, unfortunately. And this is a drug for acne, which can be disfiguring and disabling, but is not life-threatening. If it were a drug for pancreatic cancer, we wouldn't be having this discussion.

The COX-2 inhibitors look much better (in a risk-reward calculation) in the patients who cannot tolerate other anti-inflammatory drugs because of gastrointestinal problems. Vioxx itself also looks a lot more reasonable in patients who are not in the higher-risk cardiovascular categories. But it (and the others in its class) have been marketed and prescribed to all kinds of people, and the fallout is just starting. How about Pfizer's Bextra? As an article in the New York Times aptly puts it:

"Another disaster in the making? No one knows. The parallels between Vioxx and Bextra are eerie. There are mounting worries about Bextra's safety, just as there were with Vioxx. Drug-safety advocates are calling Bextra a danger, just as they did with Vioxx. Pfizer, Bextra's maker, defends its drug just as Merck did. And studies of Bextra provide ammunition to both sides, just as studies of Vioxx did.

What should the F.D.A. do? The answer is as clear as mud, just as it was with Vioxx. The twin controversies demonstrate the problems that the F.D.A. routinely faces in trying to strike the right balance between the risks and benefits of prescription drugs. There is almost never a perfect answer. . ."

Strike that "almost", guys.