Long-term effect of pizotifen treatment on growth hormone levels of underweight children, including those with anorexia nervosa.

Eight underweight children, 3 of them with anorexia nervosa, were treated for 3 months without interruption with 1.0 to 1.5 mg pizotifen per day. Their mean weight gain was 4.6 +/- 1.1 kg (range 2.5 to 11.5 kg) and their height increased by 1.4 +/- 0.5 cm (range 0 to 4 cm), as in normal controls. Before the start of and at the end of treatment with pizotifen, protracted insulin tolerance tests were performed, during which blood glucose and growth hormone (hGH) levels were measured (10 times over 2 hours). In the same patients, hGH levels were measured (6 times over 2 hours) in the late evening, during sleep. Treatment with pizotifen did not decrease the hGH response to insulin-caused hypoglycaemia. After pizotifen, some blood glucose levels were lower than before pizotifen. The mean hGH values during sleep did not change significantly after pizotifen. In 1 patient with anorexia nervosa the increased hGH levels decreased during treatment to very low levels (she gained 11.5 kg); in another patient they increased (she gained 2.5 kg). The possible mechanisms of pizotifen action are discussed briefly. There were no changes in serum prolactin levels during pizotifen administration.