Harrison-Woolrych M et al. (2006) Bruising associated with sibutramine: results from postmarketing surveillance in New Zealand. Int J Obes (Lond) 30: 1315–1317

Sibutramine is a selective serotonin reuptake inhibitor used to treat obesity. Such agents have been associated with bleeding events; the product information for Meridia® (sibutramine, Abbot Laboratories, IL, USA) states that bruising occurred in 0.7% of sibutramine-treated patients compared with 0.2% for placebo. A causal relationship had not, however, been proven.

The New Zealand Intensive Medicines Monitoring Programme included postmarketing prescription data and adverse-event reports from all 9,532 patients prescribed sibutramine between February 2001 and November 2002. Harrison-Woolrych et al. identified five cases of sibutramine-associated bruising in the New Zealand cohort, three of which resolved when sibutramine was withdrawn (two unknown); one patient experienced recurrence of bruising on sibutramine reintroduction—indicative of a causal relationship.

The authors also identified 39 reports of sibutramine-associated bruising notified to the WHO Uppsala Collaborating Centre for International Drug Monitoring. Of these, 31 had sufficient information for causality assessment; in 11 patients, bruising improved when sibutramine was withdrawn, and it recurred in one patient when sibutramine was reintroduced. In two WHO cases, however, sibutramine was not the sole drug that could cause bruising, because either aspirin or co-trimoxazole had been coadministered.

The overall risk of bruising when taking sibutramine was <1%. The authors suggest that sibutramine might reduce the amount of serotonin available for release by platelets, which could impair platelet aggregation. They advise caution in prescribing sibutramine to patients predisposed to bleeding complications, or who are on medicines that affect hemostasis or platelet function.