Discovering, testing and bringing a new drug to market can take more than a decade and cost as much as £500m. Over the past 30 years, as the costs have mounted, so have the pressures to protect new chemical agents which could become potential blockbusters.

Secrecy became the pharmaceutical industry's watchword as it sought to control publication of trials and even manipulate results. Cancer drugs introduced in the 1990s claimed to offer major benefits which later turned out to be more apparent than real. Evidence published in The Journal of the American Medical Association showed that 38 per cent of independent studies of the drugs reached unfavourable conclusions about them, compared with just 5 per cent of studies funded by the pharmaceutical industry.

In 2004, UK researchers commissioned by Nice to develop guidelines for prescribing antidepressant drugs to children tried to obtain unpublished trials from the drug companies. They were refused. They then contacted the individual researchers who had worked on the trials. Only then did a picture emerge of increased risk of attempted suicide, and a lack of efficacy. Nice concluded by banning the drugs for under-18s with the exception of Prozac.

Yesterday's report suggesting that modern antidepressants offer no significant clinical benefit over placebo has been dismissed by the drug industry as "just one study" which should not be allowed to undermine the wealth of research showing that the selective serotonin reuptake inhibitor (SSRI) antidepressants are effective.

But that is to miss the point. The Hull University researchers have demonstrated how partial access to research can give a distorted view of a drug. The non-disclosure of data on the SSRIs has raised doubts about the trustworthiness of all research on antidepressants.

We should be relieved that the licensing authorities have an absolute right to see all trial data, positive and negative, before approving a drug. But, bizarrely, Nice, with the responsibility for deciding which drugs should be used by the NHS, only gets what the drug companies agree to give it. The Health Select Committee has called for action to remedy this omission. Ministers must respond.

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