Ipamorelin vs MK-677 (Ibutamoren): Evidence and Status
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[GH peptides · Comparison]

Ipamorelin vs MK-677: how do they differ?

Route · Human trials · FDA status

Short answer: Both act on the ghrelin (GH secretagogue) receptor. Ipamorelin is an injected five-amino-acid peptide;1 MK-677 (ibutamoren) is a non-peptide pill taken once daily.2 MK-677 has more human data: in a 2-year trial in older adults it raised GH and IGF-1 and lean mass, but also fasting glucose.3 Neither is approved, and FDA lists both as compounding safety risks.4

How do ipamorelin and MK-677 compare side by side?

From published human trials, FDA compounding lists and the 2026 WADA List. Neither has a US label.
IpamorelinMK-677 (ibutamoren)
What it isPentapeptide ghrelin-receptor agonist1Non-peptide ghrelin mimetic taken by mouth23
Approval statusNot approvedNot approved
Route in human studiesIV infusion56By mouth, once daily3
Doses studied0.03 mg/kg IV twice daily for up to 7 days (ileus trial)62, 10 or 25 mg daily;7 25 mg daily for up to 2 years3
Half-lifeabout 2 hours after IV dosing5Not stated in the trial abstracts cited here
GH responseSingle GH peak about 0.67 hours after IV dosing525 mg daily raised mean 24-hour GH 97% at 2 weeks7
Main human resultsPhase 2 ileus trial: no significant difference from placebo6More lean mass but no strength or function gain in older adults;3 no effect on Alzheimer progression8
Safety signalsFDA notes serious adverse events including death in a published IV study for gastric motility4Higher fasting glucose, lower insulin sensitivity;3 hip fracture trial stopped early for a heart failure signal9
FDA compounding statusCategory 2 under 503B (September 2023)4Category 2 under 503A and 503B, citing heart failure risk4
SportWADA S2.2.4 (named)10WADA S2.2.4 (named)10

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

Why does the route matter?

Ipamorelin is a peptide and was given into a vein in its human studies, where it produced one GH pulse peaking about 40 minutes after the dose, with a half-life of about 2 hours.5 In animals it raised GH without raising ACTH or cortisol, which is why it was called selective.1 MK-677 is a non-peptide that works by mouth.2 Taken once daily, it raised 24-hour GH and IGF-1 continuously: in older adults on 25 mg, IGF-1 went from 141 to 265 micrograms per liter over 4 weeks.7

What did the MK-677 trials find?

  • Healthy older adults (2008): 65 people aged 60 to 81, 25 mg daily. Lean mass rose 1.1 kg vs a 0.5 kg fall on placebo, and weight rose 2.7 kg vs 0.8 kg. Fasting glucose rose about 5 mg/dL, insulin sensitivity fell, and there was no gain in strength or function.3
  • Hip fracture (2011): 123 older patients. IGF-1 rose, but most function measures did not improve, and the trial was stopped early for a heart failure safety signal.9
  • Alzheimer disease (2008): 563 patients for 12 months. IGF-1 rose about 73%, with no effect on disease progression.8

For ipamorelin, the one phase 2 trial (117 patients after bowel surgery) found no significant benefit over placebo.6 No trial has compared the two directly. These are study protocols, not personalized advice; confirm any dosing with your prescriber.

What has FDA said about them?

Both are on FDA's Category 2 list of bulk substances that may pose significant safety risks in compounding. For ibutamoren, FDA points to the hip fracture trial that was terminated for a possible heart failure signal. For ipamorelin (listed under 503B), FDA cites immunogenicity risk and serious adverse events, including death, reported when it was given IV for gastric motility.4

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
Ipamorelin vs sermorelin: how do they differ?Ghrelin mimetic vs GHRH analog HGH vs MK-677: how do they differ?Replacing growth hormone vs prompting your own CJC-1295 vs sermorelin: what is the difference?Same GRF 1-29 backbone, different stability

Frequently asked questions

Is MK-677 a peptide?+
No. MK-677 (ibutamoren) is a non-peptide growth hormone secretagogue taken by mouth. Ipamorelin is a five-amino-acid peptide.21
Does MK-677 raise blood sugar?+
In the 2-year trial in older adults, fasting glucose rose about 0.3 mmol/L (5 mg/dL) and insulin sensitivity fell on 25 mg daily.3
Is MK-677 FDA approved?+
No. FDA placed ibutamoren mesylate in Category 2 for compounding because of a possible heart failure risk.4
Did ipamorelin work in human trials?+
Its phase 2 trial for ileus after bowel surgery found no significant difference from placebo on the main outcome.6
Can I track ipamorelin and MK-677 in Dose Track?+
Ipamorelin is built in with reconstitution math. MK-677 is not built in, but you can add it as a custom oral medication with daily reminders.

Sources

  1. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998.
  2. Codner E, et al. Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the GH-IGF-I axis. Clin Pharmacol Ther. 2001.
  3. Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149:601-11.
  4. FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (Category 2 and nominated-but-withdrawn lists). Updated April 2026.
  5. Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin in human volunteers. Pharm Res. 1999.
  6. Beck DE, et al. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for postoperative ileus. Int J Colorectal Dis. 2014.
  7. Chapman IM, et al. Stimulation of the GH-IGF-I axis by daily oral administration of a GH secretagogue (MK-677) in healthy elderly subjects. J Clin Endocrinol Metab. 1996;81:4249-57.
  8. Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008;71:1702-8.
  9. Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a phase IIb study. Arch Gerontol Geriatr. 2011;53:183-9.
  10. World Anti-Doping Agency. The 2026 Prohibited List, in force January 1, 2026 (English text as published in the Dutch Treaty Series, Tractatenblad 2026, 25).

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