Anti-obesity drugs 'fail to reduce weight'

Anti-obesity drugs are unlikely to permanently reduce patients’ weight, Canadian research findings suggests.

A meta-analysis showed little evidence that orlistat, sibutramine or rimonabant reduced patients’ weight loss by 5 per cent.

Such ‘modest’ weight loss could mean many patients will remain significantly overweight or obese despite drug treatment, say the researchers.

The study focused on 30 randomised placebo-controlled studies into anti-obesity drugs, involving almost 20,000 patients treated for at least one year.

Analysis showed that compared with placebo, orlistat reduced weight by an average of 2.9kg, sibutramine by 4.2kg and rimonabant by 4.7kg. As the average starting weight of participants was 100kg, the drugs often failed to reduce body weight by 5 per cent.

Of note, 30-40 per cent of participants dropped out of the trials, potentially affecting perceived effectiveness of the drug.

Last December, NICE published public health guidance on obesity. Use of orlistat and sibutramine were recommended if patients with a BMI of 30 or more fail to respond to lifestyle interventions.

However, treatment should only be continued beyond six months if the patient manages to lose 5 per cent body weight in that time, according to NICE.

NICE is also carrying out a technology appraisal into rimonabant, which was licensed by the EMEA last June.

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