Imagine a pill that allowed you to eat what you like, as often as you like, but still allowed you to lose weight without any unwanted side-effects. Of course it doesn’t exist, but many of the world’s largest pharmaceutical companies have committed huge sums of money attempting to develop such a pill. The latest candidate is a synthetic version of a naturally occurring hormone, oxyntomodulin which acts as an appetite suppressant and takes away the pleasure of eating. Is this pill –codenamed OAP 189, the “wonder cure” for obesity we have all been waiting for?
Part of the impetus for the development of OAP 189, came from studies carried out in gastric bypass surgery patients. We know that the dramatic weight loss associated with bypass is largely due to an increase in various gut hormones – including oxyntomodulin – which help to suppress the appetite. In addition to the effect on appetite, these hormones also regulate blood sugar levels. This explains why 85% of type 2 diabetic patients are cured following a gastric bypass procedure. So the ideal weight loss pill would mimic the effects of these various hormones, but without the attendant risks of surgery and without any unwanted side effects. Oxyntomodulin is clearly a promising example of a new generation of weight loss drugs which could herald a new era in the medical treatment of obesity.
However, there are too many unanswered questions to claim the Holy Grail has been found just yet. Firstly, people do not overeat merely because they feel hungry; they eat for a variety of reasons including boredom, depression and stress. Secondly, even if the drug emerges intact from rigorous clinical trials, we have no idea what the long-term results will be. Obesity is a chronic, relapsing condition, so short term weight loss is not the issue. The key question is whether weight loss can be sustained. Thirdly, it is too ambitious to make any claims about a single drug mimicking the impact of a gastric bypass, because the effects of bypass surgery are mediated by many different hormones, not just one. Finally, there is the issue of safety. This area of scientific research is crowded with the remains of scores of “wonder” drugs that, despite initial hype, turned out to be not so wonderful. The most recent example was Rimonabant (Acomplia) which in June 2006 was hailed as the miracle solution to obesity and which was then withdrawn in 2008 because of serious side effects – notably an increased risk of suicide. The fact that OAP 189 is based on a naturally occurring hormone, unfortunately doesn’t guarantee that it will be free from unwanted or even serious side-effects.
Oxyntomodulin will not turn out to be a “miracle” cure for obesity, because true miracles just don’t happen. But given the continuing commitment and talent of teams of scientists, a genuinely safe and effective drug treatment for the obese may be closer to hand.
Dr David Ashton MD PhD
3rd April 2012