Growth hormone deficiency - pralmorelin
Somatotropin, or growth hormone, is essential in the control of both metabolism and growth, but if there is a deficiency in the body, either of the hormone itself or the body's response to it, the result is retarded growth.
Somatotropin, or growth hormone, is essential in the control of both metabolism and growth, but if there is a deficiency in the body, either of the hormone itself or the body's response to it, the result is retarded growth.
Growth hormone-releasing hormone (GHRH) stimulates the release of the growth hormone itself, as does the peptide hormone ghrelin, which is secreted by the stomach.
In a search for alternatives to administering growth hormone, Japanese company Kaken has identified pralmorelin as a peptide mimic of ghrelin.1 In an open label dose escalating study, six pre-pubertal children were given 0.3, 1.0 or 3.0 µg/kg/day in subcutaneous doses for consecutive two-month periods.2 For the fourth two-month period, they were given 3.0µg/day along with a similar quantity of GHRH. Levels of growth hormone increased in a dose dependent fashion in response to the drug. Growth velocities were higher during treatment than during baseline or follow-up periods.
In a further trial, intranasal doses of 5-15µg/kg were given to 15 short children twice a day for three months, and then three times a day.3 The growth rate of most of the children increased significantly - up to a mean rate of 6.1cm a year after treatment, from 3.7cm in the year beforehand.
The effects of oral doses of the drug on body weight and appetite have also been investigated.4 A total of 10 pre-pubertal children with growth hormone were given 900µg/kg twice a day for 12 months. A significant increase in appetite was reported by seven of the children, but no statistical significant increase in body mass index was observed.
It is also being investigated in adults. A trial has been carried out in 33 men with prolonged critical illness, and a combination of pralmorelin, GHRH and thyrotropin releasing hormone (TRH) gave beneficial metabolic effects; these were not seen with pramorelin alone.5 And 14 critically ill patients were given a five day infusion of pralmorelin with TRH, which reactivated GH and TRH.6
The agent has already been launched in Japan as a diagnostic agent for growth hormone deficiency. Trials continue for its use in treating people of short stature.