A patient who is taking rimonabant, a weight loss drug, runs a higher risk of experiencing severe psychiatric events, such as depression and anxiety, according to an article in The Lancet, this week’s issue.

The authors explain that as the prevalence of obesity rises unabated, the demand for effective and safe anti-obesity agents that help you lose weight, and keep it off, has grown.

Professor Arne Astrup, Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Denmark, and team carried out a multi-study of four double-blind randomized controlled trials, involving 4,105 patients – they compared patients treated with 20 mg per day with rimonabant versus others who received a placebo.

The researchers found that׃

— The rimonabant patients lost 4.7kg more than the placebo patients after one year
— The rimonabant patients ran a 40% higher risk of experiencing adverse events or serious adverse events, compared to the placebo patients
— The rimonabant patients ran 2.5 times the risk of discontinuing treatment because of depression, compared to the placebo patients
— The rimonabant patients ran 3.5 times the risk of discontinuing treatment due to anxiety, compared to the placebo patients

After treatment with rimonabant was over there were no follow-ups, the authors point out – so we don’t know whether the patients put any weight back on afterwards.

“As with other weight-loss drugs, relapse is expected to occur after treatment has ended, and to achieve weight maintenance and maintain the improvement of the cardiovascular and diabetes risk factors the drug needs to be taken for life,” the researchers explained.

“Our findings suggest that 20 mg per day of rimonabant increases the risk of psychiatric events – i.e., depressed mood disorders and anxiety – despite depressed mood being an exclusion criterion in these trials. Taken together with the recent US Food and Drug Administration finding of increased risk of suicide during treatment with rimonabant, we recommend increased alertness by physicians to these potentially severe psychiatric adverse reactions,” the authors concluded.

Accompanying Comment

“These findings are especially striking since those with a history of significant depression or other psychiatric illnesses had been excluded before study entry; there is strong evidence that people with severe obesity are at high risk of depression…[this] meta-analysis raises major questions about the safety of rimonabant in obese people, who are already at an increased risk of depression, especially since the FDA review suggests that the risk of suicide is increased with this agent,” wrote , Professor Philip Mitchell and Professor Margaret Morris, School of Psychiatry and School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.

The authors added that as other companies are currently conducting human trials on similar drugs, they need to keep an eye on psychiatric complications.

“Efficacy and safety of the weight-loss drug rimonabant” R Christensen and others
“Depression and anxiety with rimonabant” P B Mitchell, M J Morris
The Lancet – Volume 370 • Number 9600 • November 17 – 23, 2007

Written by׃ Christian Nordqvist