Characteristics of abnormal food-intake patterns in children with Prader-Willi syndrome and study of effects of naloxone.

Prader-Willi syndrome (PWS) is characterized by morbid obesity and abnormal appetite. It has been suggested that appetite is reduced by the administration of the opioid antagonist, naloxone. This has led to the hypothesis that appetite disturbance is a consequence of an abnormal hypothalamic response to appetite effects of endogenous opiates and opiate antagonist may be a useful treatment. To characterize the feeding patterns of PWS children and test this hypothesis, we administered an appetite test to 10 PWS children and 9 obese control children. We also examined the effects of naloxone on eating behavior of the children with PWS. While initial rate of eating did not differ, the PWS group showed a much delayed satiety resulting in a longer period of food intake. No difference in food intake was observed with naloxone (1.6 mg im, 30 min before the feeding test) treatment as compared with saline treatment.