Trying Two Analogues of Growth Hormone Releasing Factor Both alleviate radiation-induced growth hormone deficiency

The stimulation of growth hormone release by synthetic human pancreatic growth hormone releasing factor [hpGHRF(1-40)] and a shorter chain amidated analogue, hpGHRF(1-29) NH2, was studied in 7 normal subjects and 6 patients with radiotherapy-induced growth hormone deficiency. A single 200}J.g dose of hpGHRF(1-40) or hpGHRF(1 -29)NH2 was administered IV. Mean serum growth hormone peaks of 67 and 57 mUlL were found in normal subjects given hpGHRF(1-40) and hpGHRF(1-29)NH2' respectively. There were no significant differences between the two analogues in either peak responses or total amount of growth hormone secreted over 2 hours (hpGHRF(1-40) = 284 units; hpGHRF(1-29)NH2 = 260 units).

Megavoltage radiotherapy in 6 patients with pro/actinomas reduced the mean maximal growth hormone response to hypoglycaemia from 38 mUlL to undetectable levels, except for 1 patient whose peak serum concentration rose subnormally to 8 mUlL. Both hpGHRF(1-40) and hpGHRF(1-29)NH2 induced increases in serum growth hormone levels greater than those seen after hypoglycaemia. In 3 patients, growth hormone responses were within the normal range. These results suggest that irradiation-induced growth hormone deficiency ' ... may be due to failure of synthesis or delivery of endogenous GHRF from the hypothalamus to pituitary cells.' Grossman. A. et al .. · British Medical Journal 288: 1785 (Jun 1984)

0156-2703/ 84/ 0630-0009/ 0$01 .00/0 © ADIS Press INPHARMA® 7 Jul1984 9