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New Compound Stimulates Growth Factors In Some Children

Short-term administration of the orally active nonpeptide growth hormone secretagogue ibutamoren mesylate (MK-0677) can increase growth hormone, insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels in some children with growth hormone deficiency.

Ibutamoren mesylate stimulates growth hormone release through a pituitary and hypothalamic receptor that is different from the growth hormone -releasing hormone receptor. It should be tested for its effect on growth velocity, says an international team of investigators based at the Institute of Maternal and Child Research, University of Chile, Santiago, Chile.

They evaluated the safety and tolerability and the growth hormone-insulin-like growth factor responses to two dosages of oral ibutamoren mesylate given for seven to eight days to 15 prepubertal boys and three prepubertal girls with idiopathic growth hormone deficiency.

The children, aged 10.6 ± 0.8 years, had a bone age of 7.4 ± 0.7 years, growth velocity and height below the 10th percentile for age and a maximum growth hormone response of 10 µg/L to two different growth hormone stimulation tests.

The children were assigned to one of three treatment groups with ibutamoren mesylate. Group 1 received 0.2 mg/kg per day on days one to seven followed by matching placebo. Group 2 received 0.2 mg/kg per day on days eight to 14 preceded by matching placebo. Group 3 received 0.8 mg/kg per day on days eight to 14. On day 15, all 18 children received an 0.8-mg/kg dose of ibutamoren mesylate.

Children in groups 1 and 2 were studied first to assess safety at the low dose before advancement to the high dose. Hormonal profiles were evaluated on day 1 (baseline) and day 15.

Results were expressed as the change from baseline. In group 3, median increases from baseline on day 15 were:

- serum growth hormone peak concentration: 3.8 µg/L (range, 0-34.3)
- growth hormone area under the concentration-time curve from time zero to eight hours: 4.3 µg · h/L (range, 1.3 -35.6)
- serum insulin-like growth factor-1: 12 µg/L (range, -4-116)
- serum insulin-like growth factor binding protein: -3.0.4 µg/L (range, -0.9-1.5).

There were no changes in serum prolactin, glucose, triiodothyronine, thyroxine, thyrotropin, peak serum cortisol, insulin concentrations or 24-hour urinary free cortisol after ibutamoren mesylate 0.8 mg/kg/day for eight days.
Clinical Pharmacology and Therapeutics 2001; 70(1): 91-98. "Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone–insulin-like growth factor I axis in growth hormone–deficient children"

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