Senior doctors are claiming that some drug trials, carried out after a medicine has won its licence, are more to do with increasing sales than science. One expert claims that these tactics, carried out in low income countries such as India where people have to pay for medicines, can cause "catastrophic health expenditure" for families when the patient has to take over the cost of treatment at the end of the trial period. Post-marketing studies are often carried out even though they are not required by drug licensing authorities…the idea is that drug companies and doctors can find out how well a medicine works in the real world, when patients are not so regularly monitored and supported. But a paper published online by the British Medical Journal by Edwin Gale, emeritus professor of diabetic medicine at Bristol University, raises questions about the usefulness and real purpose of such trials.