The medication ( Contrave, by iNova) contains a combination of the opioid antagonist naltrexone and the anti-cravings drug bupropion which is an anti-depressant.
It is indicated for patients with obesity (a BMI over 30) or in patients who have a BMI over 27 plus one or more weight-related comorbidities, such as type 2 diabetes.
In one US trial, 44% of participants who were overweight or obese with type 2 diabetes achieved more than 5% total weight loss and saw improvements in glycaemic control.
In a study of patients without diabetes, 42 percent of patients lost at least 5 percent of their body weight after a year. That means that most people taking CONTRAVE did not meet the 5 percent goal.
However, the withdrawal rate from phase 3 trials was as high as 50%, with up to one-third of participants experiencing nausea.
The head of Monash University’s physiology department, Professor Michael Cowley, who developed the drug, said it worked by influencing two key areas of the brain involved in regulating food intake: the hypothalamus and mesolimbic dopamine circuit.
The drug was dual-acting, helping to control both appetite and cravings.
Prescribing requires a gradual step-up of dosing over four weeks, and complete cessation if no substantial weight loss is seen by week 16.
The medication needs to be taken for about 6 weeks before the weight loss really starts, but the withdrawal rates from earlier trials was as high as 50%, mainly due to nausea. Like most diet drugs the initial weight loss is commonly followed by weight gain upon cessation due to the increase in appetite.
The price is likely to be more than $100 per month.
Weight loss can be challenging. A diet pill sounds like the perfect solution. But there is no weight loss medication that works perfectly for everyone.