AstraZeneca has responded angrily to results of a study published in the British Medical Journal, which claim that the firm’s atypical antipsychotic, Seroquel (quetiapine), when given to Alzheimer’s sufferers actually worsens their condition, according to Industry reports.

Researchers at Institute of Psychiatry, led by Professor Clive Ballard, studied 93 Alzheimer’s patients with dementia living in care homes in Newcastle. The study concludes that those patients taking Seroquel experienced a doubling in cognitive decline, compared with the control group given placebo, while those taking Novartis’ antipsychotic Exelon (rivastigmine), showed no significant improvement in agitation but no decline in cognitive function either.

Seroquel does not have regulatory approval for dementia but is often prescribed off-label basis to treat the symptoms of Alzheimer’s and the research noted that antipsychotics are used in up to 45% of British nursing homes. A year ago, the UK’s Committee on Safety of Medicines warned that the two most common-used antipsychotics, Eli Lilly’s Zyprexa (olanzapine) and Johnson & Johnson’s Risperdal (risperidone), increased the risk of a stroke when used to treat behavioural problems in older patients with dementia [[10/03/04b]], but this study concludes that quetiapine should not be used instead.

AstraZeneca reportedly responded by saying it “remains confident in Seroquel’s safety and efficacy profile, with more than eight million patients treated since its launch in 1997.” The firm claimed the sample used was too small for significant conclusions about the drug’s effect on cognitive decline to be made and noted that five patients disproportionately influenced the results.

Seroquel is an important product for the Anglo-Swedish drugmaker, having contributed $2 billion to revenues in 2004, but the news of the BMJ article had very little effect on the firm’s share price as observers noted that larger, more significant studies have backed up AstraZeneca’s safety and efficacy claims for the drug.