Background
Sibutramine (Reductil) is a tertiary amine, originally developed as an antidepressant, but with weight-loss inducing properties. Sibutramine works to suppress the appetite, primarily by inhibiting reuptake of the neurotransmitters serotonin and noradrenaline, which help to control food intake. In practice this means that patients tend to eat less, because they feel satisfied with smaller portions of food. Sibutramine is absorbed from the gastrointestinal tract after oral administration and at least 77% of a single dose is absorbed.
Sibutramine is licensed for the promotion of weight loss as an adjunctive therapy within a weight management programme for patients with a body mass index (BMI) of 30Kg/m2 or higher, or for patients with a BMI of ³ 27 Kg/m2 in the presence of co-morbidities (eg dyslipidaemia, diabetes). Clinical trials have confirmed that it achieves clinically relevant weight loss of 5-10% of baseline weight, with consequent reduction in obesity-associated co-morbidities1. The drug is available as a 10 or 15mg capsule. The most common side effects include dry mouth, headache, constipation and insomnia. It may cause a small increase in average blood pressure, and a higher increase in some patients, hence careful monitoring is essential.
Sibutramine in Practice
Adjunctive Therapy
The first – but often forgotten – principle is that treatment with sibutramine is adjunctive, i.e. it is in addition to, not instead of long-term behavioural and lifestyle change. The current epidemic of obesity is largely environmental in origin and, unless environmental factors (excess consumption of energy-dense foods, sedentary lifestyle etc) are addressed, drug therapy will not be successful. Patients may want a magic bullet, but no drug can overcome the obesogenic effects of the environment.
Who to treat - is the patient ready for change?
At the Healthier Weight Centre (HWC), we do not prescribe sibutramine, unless there is good evidence to think the patient is ready for change. There is a paradox here. Many patients will tell their doctor that they are “desperate” and would “do anything” to lose weight, but in the very next sentence express strong resistance to a simple recommendation to walk for 20 minutes each day. Prescribing sibutramine to someone who continues to exhibit strong ambivalence to making modest lifestyle changes is a practice which will fail. It is essential for patients to understand that there is no ‘magic bullet’ and that long-term behavioural change is essential. At the HWC, poor attendance at classes and lack of record keeping, would disqualify a patient from adjunctive drug therapy – simply because it will be neither effective, nor in the patient’s best interest.
When should I prescribe the treatment?
The decision as to when to treat is as important as whether to treat. As a generalisation, I encourage patients to achieve the maximum weight loss possible without the use of drug therapy. This has the effect of allowing time for new behaviours to become established, whilst reinforcing the point that drug therapy is adjunctive. I usually introduce the medication at precisely the time when, having already lost some weight, the patient is beginning to struggle. Obviously this is because as the patient’s body weight has fallen, it becomes more difficult to create and maintain the energy deficit required for meaningful weight loss.
Sibutramine in Binge Eating Disorder
In binge-eating disorder, a person eats an abnormally large quantity of food within a 2-hour period and feels unable to control the eating behaviour. Typically, the patient eats despite not feeling hungry, feels embarrassed to be seen eating and feels guilty afterwards. Patients (mostly women) are often very distressed about the binges, which can damage self-esteem and social relationships. Various treatment options have been proposed, but there is no evidence that specific psychological intervention is any more effective than management within a structured, behaviourally orientated, weight-loss programme. There is some evidence that treatment with serotonin reuptake inhibitors may improve outcomes in binge-eaters2. At the HWC we identify potential binge-eaters by a combination of careful history taking and a standard questionnaire. Those who are identified this way are treated with sibutramine earlier in the programme than they would otherwise be. In addition, I believe these patients should be offered extended treatment with sibutramine in maintenance.
Is intermittent therapy with sibutramine effective?
Some patients report that after a period of time, sibutramine appears to become less-effective. This habituation may be partly psychological, partly physiological. Because of the possibility of habituation, the question of whether intermittent therapy may be as effective as continuous therapy could be important. In a recent study, researchers randomised patients into two groups – those taking sibutramine continuously and those taking the drug intermittently (with 6-week periods off medication)3. At 48 weeks weight loss was similar in both groups. These data suggest that intermittent therapy could be a useful approach where patients may need to be on medication for an extended period.
Dr David Ashton, Medical Director, Healthier Weight Centres
References
1. Bray GA, et al. Sibutramine produces dose-related weight loss.
Obes Res 1999; 7:189-198
2. McElroy S, et al. Placebo-controlled trial of sertraline in the treatment of binge eating disorder. Am J Psychiatry 2000; 157:1004-1006
3. Wirth A, Krause J. Long-term weight loss with sibutramine: A randomised controlled trial. JAMA 2001; 286;1331-1339
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