Sibutramine was taken off the market in Europe in January having been linked to an increased risk of cardiovascular events. No action other than label changes were taken in other major markets such as the US and Canada. The decision was based on an interpretation of a seven year trial: Sibutramine Cardiovascular Morbidity/Mortality Outcomes in Overweight or Obese Subjects at Risk of a Cardiovascular Event (SCOUT) and today the FDA Advisory panel will decide the future of the drug in the US. The results from this six year randomized clinical trial will be debated and the manufacturers, Abbot, hope that Sibutramine will remain on the approved list.
Dr. Eric Coleman, MD and deputy director of the Division of Endocrinology and Metabolism Products reviewed the drug’s efficacy in contributing to weight loss. A 2.8% reduction in body weight after 6 weeks was noted with the consumption of 10mg per day and beneficial lifestyle changes.
After randomization to Sibutramine whilst following a newer and healthier lifestyle, a decrease of 4.8% of weight after 12 months was noted with a slight increase after the twelfth month. At the 60th month, the difference in weight between those taking Sibutramine and those taking the placebo was roughly 2.8%. The average systolic and diastolic blood pressures and heart rates of those taking Sibutramine were higher than those taking the placebo.
Abbot stated that people with a history of cardiovascular illness were included in the SCOUT trial despite being contraindicated for this drug. The company maintains that the SCOUT study does satisfy benchmarks for weight loss drugs when taken by the right people. The SCOUT study proved that it should not be used incorrectly when taken by those with existing cardiovascular conditions. Abbott recognises however that due to changes in blood pressure and pulse rate, that the US label needs to be reviewed. If Sibutramine gets the all clear in the US today, then we would expect Abbott to lobby the European Medicines Agency for an urgent review of the data from the SCOUT trial.