Ministers have promised to tighten the laws that require pharmaceutical companies to disclose data from clinical trials.

The pledge comes after a drug safety watchdog announced that GlaxoSmithKline would not face criminal proceedings over claims that it withheld information on Seroxat, a bestselling antidepressant.

GSK should have been quicker to raise the alarm, however, on the risk of suicidal behaviour associated with the antidepressant in the under-18s, a report by the Medicines and Healthcare products Regulatory Agency (MHRA) has concluded.

Dawn Primarolo, the Minister for Public Health, said today that the Government would take immediate steps to secure a strengthening of the law in the UK and Europe.

She also said it wanted to make it clear to all pharmaceutical companies that, “notwithstanding the limitations that may exist in the law, they should disclose any information they have that would have a bearing on the protection of health”.

The MHRA received data from clinical trials in May 2003 showing that patients under 18 had a six or seven-fold increased risk of suicidal behaviour if they were treated with Seroxat than if they received a placebo. Data also showed that Seroxat was not effective for treating depression in children and adolescents.

Leaked documents suggested that GSK had known about these results as early as 1998, but declined to publish them or warn the regulatory agency until five years later.

The drug, among the group of antidepressants that account for 16 million prescriptions a year, was subsequently banned for use in under-18s.

GSK rejected claims that it improperly withheld trial information about the drug. But Kent Woods, MHRA chief executive, said it was disappointed that the company had not given the agency information earlier, adding that drugs companies had an “ethical responsibility” to do so.

“I remain concerned that GSK could and should have reported this information earlier than they did,” Mr Woods said. “All companies have a responsibility to patients and should report any adverse data signals to us as soon as they discover them.

“This investigation has revealed important weaknesses in the drug safety legislation in force at the time.”

Subsequent legislation had addressed the problem partially, but more still needed to be done, he said.

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