2. GHRP-2, GHRH and SRIF interrelationships during chronic administration of GHRP-2 to humans
C Y Bowers, R Granda-Ayala J Pediatr Endocrinol Metab. 1996 Jun;9 Suppl 3:261-70.
Studies with chronic GHRP-2 or GHRH administration were performed to demonstrate and better understand the interrelationships between GHRP-2, GHRH and SRIF. Normal younger and older men and women received chronic GHRP-2, GHRH or GHRP-2 + GHRH for 7-30 days. It was demonstrated that chronic administration of either GHRP-2 or GHRH could convert an additive GHRP-2 + GHRH GH response to a synergistic one. In addition, the type of synergistic response induced by chronic GHRP-2 versus GHRH was different. Whether the GH response becomes desensitized during chronic administration depends in part on the dosage and frequency of administration. The potential to learn more about the in vivo actions of GHRP relative to the regulation of GH secretion is underscored by studying the GH responses to GHRP-2, GHRH and GHRP-2 + GHRH.
3. The Safety and Efficacy of Growth Hormone Secretagogues
John T Sigalos, Alexander W Pastuszak Sex Med Rev. 2018 Jan;6(1):45-53. doi: 10.1016/j.sxmr.2017.02.004. Epub 2017 Apr 8.
Introduction: Growth hormone (GH) increases lean body mass, decreases fat mass, increases exercise tolerance and maximum oxygen uptake, enhances muscle strength, and improves linear growth. Long-term studies of GH administration offer conflicting results on its safety, which has led to strict Food and Drug Administration criteria for GH use. The potential drawbacks of exogenous GH use are believed to be due in part to impaired regulatory feedback. Aim: To review the literature on GH secretagogues (GHSs), which include GH-releasing peptides and the orally available small-molecule drug ibutamoren mesylate. Methods: Review of clinical studies on the safety and efficacy of GHSs in human subjects. Main outcome measure: Report on the physiologic changes from GHS use in human subjects including its safety profile. Results: GHSs promote pulsatile release of GH that is subject to negative feedback and can prevent supra-therapeutic levels of GH and their sequelae. To date, few long-term, rigorously controlled studies have examined the efficacy and safety of GHSs, although GHSs might improve growth velocity in children, stimulate appetite, improve lean mass in wasting states and in obese individuals, decrease bone turnover, increase fat-free mass, and improve sleep. Available studies indicate that GHSs are well tolerated, with some concern for increases in blood glucose because of decreases in insulin sensitivity. Conclusion: Further work is needed to better understand the long-term impact of GHSs on human anatomy and physiology and more specifically in the context of a diversity of clinical scenarios. Furthermore, the safety of these compounds with long-term use, including evaluation of cancer incidence and mortality, is needed. Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev 2018;6:45-53.
