Obesity drug alters brain, says scientist

A British scientist has warned that Sanofi-Synthelabo's experimental obesity drug Acomplia could alter the way people think.

Acomplia -- which turns off the biological switch that makes cannabis smokers hungry -- is seen as a potential blockbuster for the French pharmaceutical group, which is battling for control of larger rival Aventis.

Prof Steve Bloom, from Imperial College London, told a news conference on obesity that the drug worked on the cannabinoid system which affected many different parts of the brain, not just the appetite centre.

Phase III clinical trial results showed the drug not only helped people lose weight but was very useful for stopping smoking, he noted.

"That sounds great but what it is telling you is that it is altering the way you think. Maybe it will stop them getting promoted, maybe it will stop them being interested in sex," he said. "You are affecting the whole way the brain works because you are blocking this fundamental brain function."

A Sanofi spokeswoman said more than 13,000 people were taking part in clinical trials of Acomplia and no major side-effects had been reported. The most common complaints were nausea and dizziness but these effects were "mild and transient".

Bloom is a leading researcher in obesity, whose findings about the role of the hunger-regulating hormone PYY3-36 were published in the New England Journal of Medicine last September.

He complained that pharmaceutical companies were not interested in funding development of new drugs based on this hormone because it was not patent-protected.