Why is this of concern?
Rimonabant was licensed in the EU for adjunctive use in the treatment of obesity in June 2006. Advice from the MHRA in July 2007 warned that it must not be used by patients with major depression or those being treated with antidepressants, because of the risk of psychiatric side effects.
What is the new information?
A recent meta-analysis published in the Lancet examined the evidence for efficacy and safety of rimonabant from published placebo-controlled randomised controlled trials (four trials, n=4105, 12–24 weeks duration). Whereas patients receiving rimonabant lost, on average, 4.7kg of weight in the first year (P<0.0001), its use was associated with considerably more adverse events (Odds Ratio (OR) 1.4, P=0.0007) and serious adverse events (OR 1.4, P=0.03). The estimated numbers needed to harm (NNHs) were 25 and 59, respectively, i.e., these numbers of patients would need to be treated for one of them to experience one additional adverse event or serious adverse event, respectively. Further analysis identified that depression and anxiety, leading to withdrawal from the study, were more likely to occur in patients receiving rimonabant than placebo (depression: OR =2.5, P=0.01, NNH 49; anxiety OR 3.0: P=0.03, NNH 166).
This study provides high-quality evidence for an increased risk of psychiatric side effects with the use of rimonabant. In the general population the increased risk of serious psychiatric side effects is likely to be even higher with the use of rimonabant than identified in this analysis, as the clinical trials excluded people with depressed mood. This is borne out by the MHRA advice that about one in ten people who take rimonabant experience psychiatric side effects, mainly low mood and depression, and approximately one patient in every hundred may experience suicidal thoughts. Up to the end of June 2007, the MHRA had received 364 reports of psychiatric reactions with rimonabant.
Prescribers, who are considering the use of rimonabant for the treatment of patients with obesity, should be alert to the increased risk of psychiatric side effects associated with its use. Prescribers are reminded to observe the recommendations and contraindications for the use of rimonabant, in this and other respects, as detailed in the summary of product information (www.medicines.org.uk) and to report any incidences of adverse reactions suspected to be related with its use to the MHRA through its Yellow Card scheme.