GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue.
Patchett. A A AA; Nargund. R P RP; Tata. J R JR; Chen. M H MH; Barakat. K J KJ; Johnston. D B DB; Cheng. K K; Chan. W W WW; Butler. B B; Hickey. G G
Key Findings
- L-163,191 triggers GH release with an EC50 of ~1.3 nM, indicating high potency.
- Oral dosing as low as 0.125 mg/kg in dogs significantly raised GH levels.
- The compound selectively increased GH without major changes in aldosterone, LH, thyroxine, or prolactin; only modest cortisol elevation was observed.
Practical Outcomes
- For biohackers, MK‑0677 looks like a promising oral alternative to injectable GHRP‑6 for boosting growth hormone. However, human data are still pending, so any self‑experiment should start at very low doses, track cortisol levels, and be approached cautiously until more clinical evidence is available.
Summary
The study shows that the compound L-163,191 (also called MK-0677) is a very strong, oral drug that makes the body release growth hormone, working in a way that's almost identical to the peptide GHRP‑6. In animal tests it boosted GH at tiny doses and didn’t noticeably change other hormones except for a small rise in cortisol.
Abstract
A potent, orally active growth hormone (GH) secretagogue L-163,191 belonging to a recently synthesized structural class has been characterized. L-163,191 releases GH from rat pituitary cells in culture with EC50 = 1.3 +/- 0.09 nM and is mechanistically indistinguishable from the GH-releasing peptide GHRP-6 and the prototypical nonpeptide GH secretagogue L-692,429 but clearly distinguishable from the natural GH secretagogue, GH-releasing hormone. L-163,191 elevates GH in dogs after oral doses as low as 0.125 mg/kg and was shown to be specific in its release of GH without significant effect on plasma levels of aldosterone, luteinizing hormone, thyroxine, and prolactin after oral administration of 1 mg/kg. Only modest increases in cortisol were observed. Based on these properties, L-163,191 has been selected for clinical studies.
Study Information
pubmed
1995
1995-07-18T00:00:00.000Z
10.1073/pnas.92.15.7001