A former employee of AstraZeneca has told the BBC he was pressured by the firm’s marketeers to approve claims that its anti-psychotic Seroquel was not linked with weight gain, despite evidence to the contrary.

John Blenkinsopp, the company's former UK medical manager, has told the BBC Radio 4’s File on 4 programme that while clinical studies at the time Seroquel’s (quetiapine) launch “showed patients developed significant weight gain, significant both statistically and clinically”, the company’s marketing team “came at me with a number of potential claims all of which were trying to intimate that Seroquel was not associated with weight gain”.

According to Blenkinsopp, who was speaking publicly for the first time since leaving AZ in 2000, even though data seemed to suggest otherwise the company was “desperate for a differential advantage over one of the competitor products and they didn't have one”, and so pushed hard for the “neutral weight gain” claim.

“In the end I was put under quite a significant amount of pressure by the marketeers to sign off claims with regards to the lack of weight gain and I was unwilling to sign that off,” he told the programme, and added that the marketeers “made it clear it could be career limiting for me”, reports BBC News Online.

Seroquel was launched in back in 1997 for the treatment of schizophrenia and subsequently had its license extended to include the indication bipolar disorder, and has since become the Anglo-Swedish drugmaker’s second-biggest earner generating sales of around $4.45 billion a year.

Across the pond, the drug’s marketing strategy was reportedly heavily centred on the promise of neutral weight effects, and Blenkinsopp’s claims echo accusations made in thousands of current lawsuits against the company in the US, which allege that AstraZeneca withheld information and failed to adequately warn patients of side effects such as significant weight gain and an increased risk of diabetes.

The accusations have raised fresh talk of a more independent process for evaluating medicines, with Dr Fiona Godlee, editor of the British Medical Journal, telling the BBC that it is time for a “major overhaul” of the approvals process and independent clinical assessments for all new drugs.

File on 4 airs on BBC Radio 4 tonight at 20.00.