EMEA has recommended that doctors stop prescribing Sanofi-aventis' anti-obesity drug rimonabant

The European drugs watchdog, EMEA (European Medicines Agency), has recommended that doctors stop prescribing Sanofi-aventis’ anti-obesity drug rimonabant, because the risk of side effects that include serious psychiatric problems and suicide are too high.

The problems with the drug, marketed in Europe as Acomplia, were not unknown, with the US Food and Drug Administration (FDA) having already refused to approve the drug in July. Shortly after the FDA’s decision, the EMEA announced it would subject the drug to further scrutiny.

Rimonabant is a cannabinoid CB1 receptor blocker, derived from the appetite-stimulating effects of cannabis. Its ability to ease food cravings sparked interest in its possible use as a quitting aid for obese smokers. However, recent results from new clinical trials have shown that patients taking the drug are almost twice as likely to suffer from psychiatric problems as those not taking the drug.

According to an EMEA statement, ’patients who are currently taking Acomplia should consult their doctor or pharmacist at a convenient time to discuss their treatment.’

Sanofi-aventis has released a statement saying that it was complying with the EMEA’s decision but it believed the first-in-class drug ’ will remain an important therapeutic answer to a highly prevalent and increasing unmet medical need.’ Merck’s ’me-too’ alternative, taranabant, was recently dropped after failing to produce the target 5 per cent weight loss during Phase III clinical trials.

Be positive

The current rash of problems with anti-obesity drugs suggests the condition is harder to treat than initially expected. However, all is not lost as Phase II clinical trial results published by Danish researchers in The Lancet on Thursday showed that tesofensine could produce weight loss double that of rimonabant - and without the psychiatric side effects.

The drug - being developed by Danish firm NeuroSearch - inhibits the presynaptic uptake of the neurotransmitters nordrenaline, dopamine and serotonin in the brain, suppressing hunger and leading to an energy deficit which causes the body to burn fat.

Additionally, Imperial College London, UK, spin-out company Thiakis has started human clinical trials on a drug based on oxyntomodulin, the gut hormone that regulates feelings of hunger and satiety.

Matt Wilkinson

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