The effect of treatment with the oral growth hormone (GH) secretagogue MK-677 on GH isoforms

Pharmacodynamic hormonal effects of anamorelin, a novel oral ghrelin mimetic and growth hormone secretagogue in healthy volunteers

“…Another possibility is that this may represent desensitization of the GRLN to the effects of the drug. However, this is less likely because long-term treatment (6 months) with the growth hormone secretagogue MK-677 has been shown to increase IGF-1 levels by 84% compared to a 17% increase with placebo [25], in spite of showing a similar decline in GH response after its initial administration [26]. In the latter study, the serum peak total GH concentration was 23.5 mcg/L after the first MK-677 administration, 6.2 mcg/L at 2 weeks, and 5.1 mcg/L at 8 weeks.…”

Influence of intravenous administration of growth hormone releasing peptide‐2 (GHRP‐2) on detection of growth hormone doping: growth hormone isoform profiles in Japanese male subjects

“…Ten healthy male volunteers (subjects [16][17][18][19][20][21][22][23][24][25] were Japanese (Mongoloid, 20-33 years old, BMI: 19. After 2 h, 100 µg of GHRP-2 (GHRP KAKEN100  ) was intravenously administered.…”

“…[1,10] Endogenous GH releasing substances, so-called GH-releasing peptide (GHRP) or GH secretagogue (GHS), [11] such as GHS/ghrelin receptor agonists, [11 -13] or somatostatine inhibitors [14] have also been prohibited by WADA. [14 -17] The effect of treatment with oral GHS (MK-677, ibutamoren) on GH isoforms was reported; [18] however, there is no evidence of how the isoform differential immunoassay would be affected by the use of GHS, and it is unclear whether rhGH abuse can be detected if used with GHSs. [14 -17] The effect of treatment with oral GHS (MK-677, ibutamoren) on GH isoforms was reported; [18] however, there is no evidence of how the isoform differential immunoassay would be affected by the use of GHS, and it is unclear whether rhGH abuse can be detected if used with GHSs.…”

Growth hormone isoforms

“…It is not known to which degree these assays differentiate among monomeric and oligomeric forms; judging from the values and percentages reported, they probably recognize both. Using a 20K-GH specific assay, the percentage of 20K-GH as part of total plasma GH has been investigated extensively and found to range between 3% and 15%, with a mean of approximately 5.2%, with no systematic or consistent differences between adults, children, genders, age, physiological state, health and disease (see above for comments on slightly higher mean values in one study of acromegaly and anorexia nervosa) [42,45,76,85,95,97,112,113]. The relatively wide range is due to a positively skewed distribution with a few high values.…”