Mysimba’s approval in Europe in March 2015 opened up new options for obesity treatment in Europe.
Mysimba – marketed under the brand name Contrave in the US – is a combination of naltrexone and bupropion, which were both known to curb appetite by working on the brain’s signaling processes.
The European Medicines Agency (EMA) approved Mysimba for treating adult patients who have a body mass index over 30kg/m2, or to those that are 27kg/m2 to 30kg/m2 if they suffer from additional diseases related to obesity (e.g. type 2 diabetes, dyslipidemia, controlled hypertension).
The EMA’s decision points on Mysimba Europe approval
Before Mysimba and another drug were approved in March 2015, only one drug was available for obesity treatment in Europe. It’s not surprising that obesity experts in Europe voiced concerns about the dire lack of treatment options. The EMA, however, previously rejected several weight-loss drugs approved in the US citing safety concerns. What, then, got Mysimba approved?
Mysimba’s efficacy was tested in several different trials lasting 56 weeks. The average weight loss ranged from -8.1% to -3.7% for patients taking Mysimba, compared to -4.9% to -1.3% in the placebo treatment. Overall, 28-48% of patients taking Mysimba lost more than 5% of their body weight over the course of the 56-week trials. On the other hand, this was 12-23% for those receiving placebo treatment.
Patients taking Mysimba also got bonus perks, including changes to their waist size and less “bad” cholesterol in their blood.
But those who took Mysimba also experienced various side effects like nausea, constipation, headaches, vomiting, dizziness, insomnia, and dry mouth more frequently than those in the placebo treatment. Some patients also experienced negative effects on mental health after taking Mysimba. Although these symptoms were rare compared to other side effects, they did occur more frequently among Mysimba takers. In fact, Mysimba trials had a high drop-out rate; some experts suspect that the severity of side effects may be to blame.
What’s more, the amount of weight loss wasn’t particularly remarkable. Patients who took Mysimba ultimately lost only 3-4% more than those in the placebo treatment. Though the difference was statistically significant, this is considered a modest to moderate outcome.
In addition to this, there are a number of uncertainties regarding how Mysimba could affect the heart and blood vessels, as well as increasing the risk of seizures. Because Mysimba’s effects are moderate at most, some experts were strongly opposed to having Mysimba in Europe; they argued that the small improvements don’t justify the side effects patients suffer and the risks Mysimba exposes them to.
Ultimately, the EMA’s verdict was that the net benefit still outweighs the costs; they say that although the side effects may be discomforting, patients can simply stop taking Mysimba if the side effects are too severe for them. As a result, they granted Mysimba approval in Europe.
Recently, Orexigen obtained more promising study results about Mysimba’s potential. Patients who took Mysimba in concert with a commercial weight loss program lost nearly 10 percent of their body weight after 26 weeks, as opposed to 0.9 percent in a business-as-usual situation. Furthermore, those who made it through the program at 26 weeks generally maintained the reduced body weight until the entire of the trial at 78 weeks.
Regulations for safety
With the potential risks in mind, the EMA set rigorous guidelines for using and monitoring Mysimba in Europe.
First, there is a mandatory re-assessment of treatment with Mysimba after 4 months. Only those who see reasonable improvement (at least 5%) during this time span are allowed to continue with the treatment. The EMA also listed Mysimba under medicines under additional monitoring, which requires the drug to be monitored with more care than usual. Rules for risk management are also in place to ensure that physicians and patients use Mysimba safely. Doctors also receive guidance about quitting the treatment for patients if they don’t see sufficient results or if there are concerns about side effects. Companies marketing Mysimba will also further investigate how the drug affects the heart and blood vessels.
A year after getting Mysimba approved: Mysimba launch in Spain
Orexigen markets Mysimba in Europe through European partner companies. Mysimba launched in Spain in January 2017 through Orexigen’s partner, Laboratorios Farmacéuticos Rovi , SA. A further Mysimba launch is expected in Central and Eastern Europe through Valeant Pharmaceitucals international, Inc, according to Orexigen’s business priorities as of January 2017.
*Mysimba is a prescription only drug, consult your doctor before use.