The drugmaker failed to accurately reflect side effects of its Seroquel antipsychotic in an ad aimed at doctors, according to the Prescription Medicines Code of Practice Authority. To be specific, AstraZeneca breached three points of the code by claiming its drug had “a favourable weight profile across the full dose range” compared with rival drugs, The Financial Times writes.

The decision by the authority, which is the self-regulatory arm of the Association of the British Pharmaceutical Industry, will be a blow to AstraZeneca as it defends itself against numerous lawsuits brought by patients in the US, the FT pointedly notes (background here). The drugmaker recently agreed to pay $520 million to settle two federal investigations (see here).

In the US, AstraZeneca claimed in ads that Seroquel resulted in lower weight gain than other antipsychotics, although several studies in highly respected academic journals suggested otherwise. In the UK, the drugmaker avoided comparative claims, but an ad in the British Journal of Psychiatry in 2004 made the claim in large print, although small print noted weight gain was a “common” side effect, the FT writes.

In its defense, AstraZeneca said health professionals would have understood Seroquel resulted in weight gain and had a favorable profile compared with other antipsychotics at the time. It quoted two scientific papers showing lower weight gain with Seroquel than another drug; and an analysis of different papers showing weight gain from five drugs, but which did not include Seroquel, the FT continues.

But the PMCPA highlighted shortcomings in the studies and ruled the ad was misleading because it didn’t reflect the evidence. The upshot - a breach of ethical code requirements. AstraZeneca tells the FT it is examining how to respond.