Therapy Analysis - Anorexia & Bulimia
Treatment
Eating disorders, like most other mental illnesses, are treated using a combination of psychotherapy and pharmacotherapy. It is not unusual to hospitalize anorexic and bulimic patients in order to monitor eating behaviour and to treat dehydration, electrolyte imbalances or severe psychiatric problems, although some treatment centres offer day clinics, which provide nutritional therapy to help patients achieve a healthy weight, without the severity of full hospitalization. The most common approach to psychotherapy is cognitive behavioural therapy to address distorted cognitions regarding weight and shape.
It is only once the patients have gained some weight that doctors are able to prescribe drug treatments, usually in the form of antidepressants and anxiolytics. Indeed, the importance in treating the underlying anxiety and depression in both anorexia and bulimia is as important as changing eating behaviour. Although the difference between the two disorders seems relatively slight, the treatments used are quite different, with no drugs in development for both indications.
Our data shows that Eli Lilly's Prozac (fluoxetine), a selective 5-HT reuptake inhibitor, is the only drug launched for the treatment of bulimia (Table 1). In a Phase II trial, it proved significantly superior to placebo in reducing the frequency of binge-eating and vomiting, and is also additionally launched for the treatment of depression, anxiety and obsessive-compulsive disorder, all of which are associated with the disease itself. This mode of action appears to be the most common in the treatment of bulimia, confirmed by our data, which highlights 3 5-HT reuptake inhibitors in active development (Graph 1), including Biovail's solubilityenhanced oral formulation of fluoxetine, which is awaiting registration in the US for the above indications, and Pfizer's sertraline, currently in Phase II trials for bulimia and binge eating disorder. There are also some reports that Zofran (ondansetron), a 5-HT3 antagonist indicated as an antiemetic, might have some use in bulimia.
Treatments for anorexia are of a different nature and according to our data, none are yet launched (Table 2). Daiichi is currently conducting Phase I trials with its gherelin agonist, SUN-11031. This acts to simulate the biological effects of gherelin, which has been shown to enhance the use of carbohydrates and reduce fat utilization, and therefore may also enhance fat storage. It has been found to induce weight gain and strong feeding impulses in rodents. Neurocrine Biosciences also sees potential in a biological anorexia therapy, in the form of its preclinical candidate, a corticotropin releasing factor 2 receptor (CRF-2) antagonist. This may be useful as a stimulant for food intake, as CRF-2 controls energy expenditure and food intake by decreasing the desire for food.
Other psychotropic medicines are used to treat the psychiatric symptoms associated with anorexia. Anxiolytics can be administered prior to food to reduce the anxiety associated with eating. Also, hormone replacement therapies have been used to replace estrogen and prevent the onset of osteoporosis in anorexics with chronic amenorrhea, but this has not proven to be particularly beneficial. Our data show 3 drugs in active development as appetite stimulants for the non-nervosa form of anorexia, and in illnesses where there is a concomitant loss of appetite such as cancer. Such appetite stimulants could prove to be very useful in the treatment of anorexia nervosa, as an adjunct to psychological therapy.
These highly prevalent syndromes appear to be overlooked by the pharmaceutical industry, with only a handful of drugs in development and even fewer launched for the diseases. The lack of scientific understanding of eating disorders results in a high R&D risk for pharmaceutical companies, and with the current treatment strategies predominantly involving psychotherapy, there seems even less of an incentive for novel therapy development. However, pharmaceutical companies still see limited potential in treating the ill-effects of anorexia and bulimia.
With increasing research into the neurobiological etiology of the disorders, the possibility of developing breakthrough therapies is improving, but with optimism for a crack-down on pro-eating disorder websites, and the ever-increasing media awareness of devastating consequence of the disorders, we can hope that these fatal diseases will simply go out of fashion.
Sophie Green
Pharmaprojects Analyst
Image courtesy of Dr Mohamed Osman, MD
