Can I take Viagra till I need glasses?

Yeah yeah, I'm sure a million people have already used that line but what the heck.

It may well turn out that Viagra does not increase the risk of blindness, but regardless, the latest post-marketing drug safety flap reminds us of something very important. As Paracelsus (1493-1541 wrote, "All substances are poisons; there is none which is not a poison." Pharmaceuticals are, by definition, powerfully biologically active substances. Most of the stuff in your medicine cabinet would kill you if you swallowed only a few grams of it. Indeed, on that basis -- the dose required to kill the average person -- nicotine is 100 times as toxic as DDT. But of course we have banned the use of DDT in the United States, while it is perfectly legal to purchase and ingest nicotine (although not recommended), although DDT has a legitimate economic use and nicotine is simply an addictive drug.

Drugs inevitably come with risks as well as benefits. Our problem is not that the FDA approves drugs which turn out to be unsafe. That can't be helped. The problem is that we often find out about risks of drugs only after they have been approved and widely marketed, and those unpleasant surprises often mean that people would have chosen not to take the drugs after all. This is difficult to avoid entirely, but the problem is greatly exacerbated by our system for evaluating the safety and effectiveness of new drugs. For the most part, the manufacturers pay for drug trials, and they frequently make investigators sign contracts that give the drug companies control over the data and publication of results. They suppres unfavorable information, and design trials so as to show their products in the most favorable light -- as by comparing them with alternatives they already know are not the best available, limiting trial subjects to people with comparatively low risk of adverse effects, limiting the length of follow up, etc.

This system needs to be radically redesigned, to serve the public interest rather than the profit interest of manufacturers of proprietary drugs. We'll discuss some options here in the days ahead.