Dr. Colin Doherty:

I am concerned about that. Let me refer to some of the newer drugs that have come through the more conventional role. We have been finding that these drugs have behavioural effects that did not come out in the original trials. The usual number of patients that are required to get a drug across the line into the regulatory zone is sometimes between a couple of thousand to 3,000 to 4,000. If something happens in only one in 5,000 children, one will not see that in the original trials. There are a number of examples going back in history, for example, the drug Vigabatrin, which is still used today, was released in 1991 to great acclaim. It was thought it would be a great addition to the treatment of epilepsy. By 1996, it was clear that it was causing blindness in a small number of people. That drug was banned initially, but now it has been reintroduced in very limited circumstances. It took five years to realise that in a small number of people it causes a severe side effect.