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RUO · Research Use Only⚠ IGF-1 Elevation+2 more

MK-677 (Ibutamoren)

An oral, non-peptide ghrelin mimetic. We read all 60 studies. The protocol is below.

Updated 03 May 2026Read 12 minEvidence ●●●○○Citations 60
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The MK-677 (Ibutamoren) Report · $19

Everything you need to start: dose, sourcing, safety, our verdict.

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Built from 60 cited studies.

Status
Research-only
Class
IGF-1 Elevation
Evidence
3/ 5●●●○○
Phase 2 / 3 trials
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IGF-1 rise
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Oral only — no injectable form
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⚠ Cancer Concern · WADA-banned
Read this if
  • **top-of-page sorter — MK-677 is oral only. There is no injectable form.** The pharmacology is designed for oral bioavailability; anyone selling 'injectable MK-677' is selling a chemistry-class violation. If you came looking for an injectable, you came to the wrong page
  • you've been pinning anabolics and want a non-injectable GH-secretagogue layer
  • you're an older lifter who wants to keep training quality but can't pin every day
  • you're a women's-bodybuilding athlete and the water-retention pre-show effect is the tool you want
Skip this if
  • you have heart failure, severe edema, or pre-diabetes drifting toward T2D — water retention and insulin resistance are the side-effect spine
  • you compete in a tested sport — WADA-banned
  • you have active or recent cancer
The 4 ways you can buy MK-677 (Ibutamoren)
Brand
✗
Not available
No FDA-approved MK-677.
Compounded 503A
✓
Off-label
$90–$200/mo where sold
Mid–high. Small molecule, atypical for 503A; few compounders carry.
RUO (research-only)
✓
Sold 'for research only'
$30–$90/mo
Sold as 'SARMs'-adjacent oral solutions; purity rarely tested. Often mis-labeled with other ghreli…
Gray market
✓
Unregulated overseas import
Varies — not on user's vendor list
Small molecule — gray path is Chinese chemical suppliers, not the peptide raws this vendor list co…
Click any lane for the full Sourcing breakdown.
First 90 days · MK-677 (Ibutamoren)
Weeks 1–2
First-night signal. Sleep peptides work the night you take them or they don't. Build-up over weeks is not how this class works.
Weeks 4–8
Tolerance can build. If you need more dose to get the same effect, the signal is degrading. Most sleep peptides should be cycled (5-on-2-off, or similar), not run continuously.
Week 12 — decide
Decide. Continuous use is rarely the right pattern. If you're at week 12 still taking it nightly, you've probably built tolerance and aren't getting the original effect.
Quit if
  • Rebound insomnia on off days.
  • Increased daytime anxiety.
  • No perceptible sleep improvement in week 1 (week-2 placebo doesn't count).
Identity

What it is.

MK-677 (ibutamoren) is an orally bioavailable non-peptide ghrelin-receptor agonist developed by Merck in the 1990s. It's not technically a , but it occupies the same pharmacological slot as the GHRPs — it triggers a GH pulse through the -R1a receptor — and it shows up in every peptide conversation, so we cover it here.

The distinctive feature is that it's active orally. One pill, daily, raises GH and for roughly 24 hours. No injections. That's the entire commercial appeal.

Merck took it through Phase 2 trials for several indications — frailty in the elderly, muscle wasting, GH deficiency. The program was abandoned. The reason wasn't that it didn't work; it's that it produced insulin resistance, edema, and congestive heart failure in a frail-elderly trial. Now sold strictly as a research chemical (RUO) in the US. WADA-banned in and out of competition.

TL;DR

TL;DR. 30-second version.

The compressed verdict — what MK-677 (Ibutamoren) actually is, what the human evidence shows, and the watch-for in three bullets. Locked.

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Mechanism

Mechanism.

Mechanism · in the MK-677 (Ibutamoren) report

How the molecule actually works — receptor profile, downstream signaling, what to expect mechanistically.

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Evidence

Evidence. What we actually know in humans.

Evidence · in the MK-677 (Ibutamoren) report

The trial breakdown — phase, n, primary endpoint, who funded, what hit, what didn't.

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Human-Evidence Factbox
Phase 2 / 3 trials
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IGF-1 rise
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Oral only — no injectable form
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First 2 weeks
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Weeks 4–8
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Weeks 8–12
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>12 weeks
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STOP triggers
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WADA status
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Merck status
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Dose

Dose. The actual protocol.

Dose · in the MK-677 (Ibutamoren) report

The specific protocol — dose, titration schedule, cycle pattern, frequency, route.

We read 60 studies to write this report.
Get the report · $19 ↓
Sourcing

Sourcing. Where the cohort actually buys.

Sourcing · in the MK-677 (Ibutamoren) report

Sourcing breakdown — vendor methodology, red flags, our published test results, COA checklist.

We read 60 studies to write this report.
Get the report · $19 ↓
Safety

Safety. Side effects.

Safety · in the MK-677 (Ibutamoren) report

The watch-for list — contraindications, drug interactions, monitoring labs, when to stop.

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Editorial Position

Editorial position.

Editorial Position · in the MK-677 (Ibutamoren) report

Our editorial position — explicit yes / no / depends, with the reasoning behind it.

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Citations

Citations.

  1. 01Murphy MG, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. The Journal of clinical endocrinology and metabolism. 1998;83(2):320-5. PMID: 9467534.
  2. 02Cardaci TD, et al. LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report. Experimental physiology. 2022;107(12):1467-1476. PMID: 36303408.
  3. 03Cobani E, et al. Hepatotoxicity induced by MK-677. BMJ case reports. 2025;18(7). PMID: 40675653.
  4. 04Lee J, et al. Effect of the Orally Active Growth Hormone Secretagogue MK-677 on Somatic Growth in Rats. Yonsei medical journal. 2018;59(10):1174-1180. PMID: 30450851.
  5. 05Sigalos JT, et al. The Safety and Efficacy of Growth Hormone Secretagogues. Sexual medicine reviews. 2018;6(1):45-53. PMID: 28400207.
+Show all 60 citations
  1. 06Bright GM, et al. A GH Secretagogue Receptor Agonist (LUM-201) Elicits Greater GH Responses than Standard GH Secretagogues in Subjects of a Pediatric GH Deficiency Trial. Hormone research in paediatrics. 2022;95(1):76-81. PMID: 35354138.
  2. 07Sinha DK, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Translational andrology and urology. 2020;9(Suppl 2):S149-S159. PMID: 32257855.
  3. 08Kintz P, et al. Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue. Clinica chimica acta; international journal of clinical chemistry. 2026;578:120578. PMID: 40882886.
  4. 09Philip M, et al. Characterization of growth hormone secretagogue small molecule ibutamoren (MK-0677) and its possible metabolites in thoroughbred horses for doping control. Rapid communications in mass spectrometry : RCM. 2022;36(18):e9337. PMID: 35716382.
  5. 10Murphy MG, et al. Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 1999;14(7):1182-8. PMID: 10404019.
  6. 11Chong S, et al. Reversible Gynecomastia and Hypogonadism Due to Usage of Commercial Performance-Enhancing Supplement Use. JCEM case reports. 2024;2(8):luae148. PMID: 39145153.
  7. 12Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Archives of gerontology and geriatrics. 2011;53(2):183-9. PMID: 21067829.
  8. 13Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008;71(21):1702-8. PMID: 19015485.
  9. 14Murphy MG, et al. Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women. The Journal of clinical endocrinology and metabolism. 2001;86(3):1116-25. PMID: 11238495.
  10. 15Viljanto M, et al. Detection of the growth hormone secretagogue MK-0677 in equine hair following oral administration. Drug testing and analysis. 2023;15(3):361-367. PMID: 36354265.
  11. 16Xu H, et al. Design, Biological Characterization, and Discovery of Capromorelin Derivatives as Oral Growth Hormone Secretagogue Receptor Type 1a Agonist for the Treatment of Growth Hormone Deficiency. Journal of medicinal chemistry. 2025;68(6):6766-6788. PMID: 40091212.
  12. 17Liu H, et al. Structural basis of human ghrelin receptor signaling by ghrelin and the synthetic agonist ibutamoren. Nature communications. 2021;12(1):6410. PMID: 34737341.
  13. 18Copinschi G, et al. Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man. Neuroendocrinology. 1997;66(4):278-86. PMID: 9349662.
  14. 19Codner E, et al. Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children. Clinical pharmacology and therapeutics. 2001;70(1):91-8. PMID: 11452249.
  15. 20Patchett AA, et al. Orally active growth hormone secretagogues. Pharmaceutical biotechnology. 1998;11:525-54. PMID: 9760695.
  16. 21Smith RG. Development of growth hormone secretagogues. Endocrine reviews. 2005;26(3):346-60. PMID: 15814848.
  17. 22Stawerska R. New directions in growth hormone treatment in children. Pediatric endocrinology, diabetes, and metabolism. 2025;31(4):143-154. PMID: 41693185.
  18. 23Hanauer SB. Sarcopenia and the elusive fountain of youth. Nature clinical practice. Gastroenterology & hepatology. 2009;6(1):1. PMID: 19127276.
  19. 24Philip M, et al. Characterization of equine liver microsome-generated metabolites of growth hormone secretagogue small molecule ibutamoren. Rapid communications in mass spectrometry : RCM. 2021;35(23):e9201. PMID: 34542924.
  20. 25Tomillero A, et al. Gateways to clinical trials. Methods and findings in experimental and clinical pharmacology. 2009;31(2):107-46. PMID: 19455266.
  21. 26Barrios MM, et al. SARMs, Metabolic Modulators and Growth Hormone Secretagogues in Suspected Illegal Medicines, Bought as Sport Performance Enhancers: A Retro- and Prospective Study Within the GEON. Drug testing and analysis. 2025;17(10):2078-2085. PMID: 40551438.
  22. 27Chapman IM, et al. Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults. The Journal of clinical endocrinology and metabolism. 1997;82(10):3455-63. PMID: 9329386.
  23. 28Smith RG, et al. Peptidomimetic regulation of growth hormone secretion. Endocrine reviews. 1997;18(5):621-45. PMID: 9331545.
  24. 29Svensson J, et al. Discrepancy between serum leptin values and total body fat in response to the oral growth hormone secretagogue MK-677. Clinical endocrinology. 1999;50(4):451-6. PMID: 10468903.
  25. 30Svensson J, et al. Treatment with the oral growth hormone secretagogue MK-677 increases markers of bone formation and bone resorption in obese young males. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 1998;13(7):1158-66. PMID: 9661080.
  26. 31Svensson J, et al. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. The Journal of clinical endocrinology and metabolism. 1998;83(2):362-9. PMID: 9467542.
  27. 32Yoon YS, et al. Antiviral activity of sertindole, raloxifene and ibutamoren against transcription and replication-competent Ebola virus-like particles. BMB reports. 2020;53(3):166-171. PMID: 31964466.
  28. 33Svensson J, et al. Treatment of obese subjects with the oral growth hormone secretagogue MK-677 affects serum concentrations of several lipoproteins, but not lipoprotein(a). The Journal of clinical endocrinology and metabolism. 1999;84(6):2028-33. PMID: 10372705.
  29. 34Svensson J, et al. The effect of treatment with the oral growth hormone (GH) secretagogue MK-677 on GH isoforms. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 2003;13(1):1-7. PMID: 12550076.
  30. 35Chapman IM, et al. Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects. The Journal of clinical endocrinology and metabolism. 1996;81(12):4249-57. PMID: 8954023.
  31. 36Yau M, et al. Treatment of Pediatric Growth Hormone Deficiency With Oral Secretagogues Revisited. Journal of the Endocrine Society. 2021;5(7):bvab096. PMID: 34141995.
  32. 37Hakim RM, et al. Anabolic interventions in ESRD: light at the end of the tunnel?. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2009;54(2):201-4. PMID: 19556045.
  33. 38Smith RG. The aging process: where are the drug opportunities?. Current opinion in chemical biology. 2000;4(4):371-6. PMID: 10959763.
  34. 39Cutler C, et al. Equine metabolism of the growth hormone secretagogue MK-0677 in vitro and in urine and plasma following oral administration. Drug testing and analysis. 2022;14(7):1273-1290. PMID: 35302297.
  35. 40Ghigo E, et al. Orally active growth hormone secretagogues: state of the art and clinical perspectives. Annals of medicine. 1998;30(2):159-68. PMID: 9667794.
  36. 41Shimatsu A. [Ghrelin-related drugs: clinical perspectives]. Nihon rinsho. Japanese journal of clinical medicine. 2004;62 Suppl 9:435-8. PMID: 15506422.
  37. 42Bayes M, et al. Gateways to clinical trials. Methods and findings in experimental and clinical pharmacology. 2006;28(9):657-78. PMID: 17200730.
  38. 43Prahalada S, et al. Insulin-like growth factor-1 and growth hormone (GH) levels in canine cerebrospinal fluid are unaffected by GH or GH secretagogue (MK-0677) administration. Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme. 1999;31(2-3):133-7. PMID: 10226793.
  39. 44Blackman MR. Use of growth hormone secretagogues to prevent or treat the effects of aging: not yet ready for prime time. Annals of internal medicine. 2008;149(9):677-9. PMID: 18981489.
  40. 45Abdul Ghafoor N, et al. Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines. Basic & clinical pharmacology & toxicology. 2025;136(1):e14111. PMID: 39668330.
  41. 46Svensson J, et al. Effects of growth hormone and its secretagogues on bone. Endocrine. 2001;14(1):63-6. PMID: 11322502.
  42. 47Komatsu Y, et al. [Ghrelin and bone metabolism]. Nihon rinsho. Japanese journal of clinical medicine. 2004;62 Suppl 9:384-7. PMID: 15506410.
  43. 48Minamitake Y. [Structure-activity relationship of ghrelin]. Nihon rinsho. Japanese journal of clinical medicine. 2004;62 Suppl 9:328-31. PMID: 15506395.
  44. 49Micic D, et al. Growth hormone secretagogues: the clinical future. Hormone research. 1999;51 Suppl 3:29-33. PMID: 10592441.
  45. 50Ghigo E, et al. Endocrine and non-endocrine activities of growth hormone secretagogues in humans. Hormone research. 1999;51 Suppl 3:9-15. PMID: 10592438.
  46. 51Lu Z, et al. Highly potent growth hormone secretagogues. Bioorganic & medicinal chemistry letters. 2007;17(13):3657-9. PMID: 17482461.
  47. 52Smith RG, et al. Growth hormone releasing substances: types and their receptors. Hormone research. 1999;51 Suppl 3:1-8. PMID: 10592437.
  48. 53Svensson JA, et al. Clinical and experimental effects of growth hormone secretagogues on various organ systems. Hormone research. 1999;51 Suppl 3:16-20. PMID: 10592439.
  49. 54Robinson IC. Hypothalamic targets for growth hormone secretagogues. Acta paediatrica (Oslo, Norway : 1992). Supplement. 1997;423:88-91. PMID: 9401551.
  50. 55Svensson J. Growth hormone secretagogues as therapeutic agents. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 1999;9 Suppl A:107-9. PMID: 10429892.
  51. 56Muccioli G, et al. Growth hormone-releasing peptides and the cardiovascular system. Annales d'endocrinologie. 2000;61(1):27-31. PMID: 10790589.
  52. 57Smith RG, et al. Growth hormone secretagogue receptor family members and ligands. Endocrine. 2001;14(1):9-14. PMID: 11322507.
  53. 58Smith RG, et al. Ghrelin receptor (GHS-R1A) agonists show potential as interventive agents during aging. Annals of the New York Academy of Sciences. 2007;1119:147-64. PMID: 18056963.
  54. 59Piper T, et al. An in vitro assay approach to investigate the potential impact of different doping agents on the steroid profile. Drug testing and analysis. 2021;13(5):916-928. PMID: 33283964.
  55. 60Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Annals of internal medicine. 2008;149(9):601-11. PMID: 18981485.
The MK-677 (Ibutamoren) Report · $19

Everything you need to start.

Dose, sourcing, safety, our verdict. One purchase. Yours forever.

Built from 60 cited studies.

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