Sibutramine ( Meridia, Reductil ), a serotonin and norepinephrine reuptake inhibitor ( SNRI ), is an antiobesity agent marketed in Canada since February 2001. Sibutramine is indicated as adjunctive therapy within a weight management program for obese patients with an initial body mass index ( BMI ) of 30 kg/m2 or higher, and for obese patients with an initial BMI of 27 kg/m2 or higher in the presence of other risk factors ( e.g., controlled hypertension, type 2 diabetes, dyslipidemia, visceral fat ).

Health Canada continues to receive reports of adverse reactions ( ARs ) in patients using Sibutramine who have contraindications. From Jan. 1, 2001, to May 31, 2007, Health Canada received 65 reports of cardiovascular ARs suspected of being associated with Sibutramine. Thirteen of these reports involved patients with at least 1 contraindicated condition.

A brief description of these 13 cases

A patient with a history of myocardial infarction who was taking Fluoxetine ( Prozac ) experienced fatal ventricular fibrillation 2 days after starting sibutramine therapy.

A patient with a history of myocardial infarction experienced a non ST-segment elevation myocardial infarction 21 days after starting Sibutramine therapy.

Three patients experienced serotonin syndrome, with cardiovascular ARs ( e.g., hypertension, palpitation and tachycardia ), from the concomitant use of a selective serotonin reuptake inhibitor ( SSRI ) and Sibutramine.

Five patients with a previous history of arrhythmia had arrhythmia while taking Sibutramine.

One patient took 10 capsules in 3 days and experienced tachycardia and confusion during concomitant use of Sibutramine with other weight-reducing agents not currently authorized for sale in Canada.

One patient, who experienced unstable hypertension after surgery, resumed her preoperative regimen of Sibutramine 2 days after surgery and experienced worsening hypertension, headache and cerebral edema. In this case, Meperidine was reported as a co-suspect drug.

One patient experienced a vitreous hemorrhage approximately 10 days after starting Sibutramine therapy. In this case, Paroxetine ( Paxil, Seroxat ) and Bupropion ( Wellbutrin ) were stopped 1 day before Sibutramine was started.

Sibutramine used at therapeutic doses has been reported to substantially increase blood pressure and heart rate in some patients. Such increases were observed within the first 4 months of therapy. Regular monitoring of blood pressure and heart rate is required when prescribing Sibutramine.
In the first 3 months of treatment, these parameters should be checked at least every 2 weeks and regularly every 1-3 months thereafter.

In 2002 and 2003, international regulatory actions were taken, including safety notices, concerning cardiovascular ARs associated with Sibutramine.
Health Canada and other foreign regulatory agencies reviewed the safety of Sibutramine and concluded that the benefit-risk profile of Sibutramine remained favourable.

Source: Health Canada, 2007

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