The FDA approved the drug Belviq in 2012. This approval came with the requirement that the manufacturer of the drug, Eisai, would complete a 5-year double-blind clinical trial utilizing a controlled placebo method. Over 5 years, this study involved 12,000 participants; some of these participants were given the placebo while others were given Belviq. Out of all the participants, 96% completed the study to the end. It was the results of that 96% that were evaluated by the FDA.
The original intention of the study was to assess the risk of cardiovascular problems that may be associated with taking Belviq in participants who already had cardiovascular disease or who otherwise had at least one risk factor for cardiovascular disease. On this front, the study found that there was no increased risk for cardiovascular-averse events in patients who were taking Belviq versus patients who were taking the placebo pills.
However, the results showed a different type of risk: an increased risk of cancer for users of Belviq. The double-blind study conducted by the manufacturer of Belviq found that participants who took Belviq had a higher rate of cancer development than participants who took the placebo for the duration of the study.