Despite the years of research and clinical trials, a drug may still turn out to have harmful side-effects
A 78-year-old man prescribed an antifungal agent after treatment for leukaemia began to hear music in his head. It was so realistic that he wrote to his hospital to complain and compiled a list of the song titles, which included ‘Do You Hear What I Hear?’ Doctors changed his medication, and the music stopped.
In another unusual series of cases, patients using a particular drug for Parkinson’s disease turned into compulsive gamblers. One female patient lost US$100,000.
These cases illustrate extremely rare side-effects, but adverse drug reactions as a whole are surprisingly common. In the UK, about 250,000 people are admitted to hospital each year because of adverse reactions – roughly 5 per cent of all hospital admissions. They are responsible for around 5,000 deaths annually (more than the number of people killed on the roads). In the USA, the number of adverse reactions – and related deaths – nearly tripled between 1998 and 2005. Five of the top six killers were painkillers.
Such numbers have to be set against the enormous beneﬁts that pharmaceuticals bring, but they do illustrate that drugs are powerful agents. As well as seeking to discover new agents, pharmaceutical companies also work to reduce the unwanted side-effects of existing ones.
‘Safety’ is not an absolute: it involves a cost–beneﬁt analysis, weighing up the risks with the beneﬁts. These will depend on the drug, the nature of the illness, the availability of alternatives – and individual choice.