How safe is safe?
No matter how hard we try, no medicine will ever be perfectly safe. Many potential therapeutics are abandoned because they are deemed too toxic; some are introduced but are later withdrawn because of dangerous side-effects.
But have our expectations become too high? In the past, greater risks were accepted. Salvarsan, an early mass-produced drug, was used to cure syphilis but had nasty side-effects and was often itself fatal. Even today, Melarsoprol, used to treat sleeping sickness in Africa, kills up to one in 20 of the people it is given to.
Over the past decades, drugs have mostly become safer and with fewer side-effects.A major turning point was the thalidomide disaster, which highlighted significant deficiencies in the way that new drugs were tested. We may have safer drugs now, but the numbers of new drugs being launched each year has dropped.
Developing drugs is now a long and expensive process. The pharmaceutical industry warns that excessive regulation - and the addition of new hurdles, such as cost-effectiveness - will reduce the number of drugs produced. Critics of the industry argue that companies use clinical trials creatively to get the results they want, or report data selectively, in order to secure licences and encourage use.
The Vioxx story has raised fears about the effectiveness of regulatory systems. There are concerns about several other pharmaceuticals, such as Seroxat (paroxetine) and suicide risk in young people, or Zelnorm (tegaserod) and heart attacks. Unlike with thalidomide, the link between medication and adverse effect may not be not clear-cut and is often disputed.
But there is another side to the Vioxx story. It is still an effective drug, and some people might be willing to accept a known risk. Both the USA and Canada have reapproved it in principle but the manufacturer has not made it available.