Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of Ipamorelin and MK-677 — mechanism, dosing, side effects, legal status, and pricing.
Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) originally developed by Novo Nordisk and later advanced by Helsinn/Nycomed. It is a selective ghrelin receptor agonist / growth hormone secretagogue (GHRP). Its defining feature versus older GHRPs (GHRP-2, GHRP-6, hexarelin) is that in preclinical and early clinical studies it raised GH without meaningfully increasing ACTH, cortisol, or prolactin. It is not FDA-approved for any indication; a Phase 2 trial for postoperative ileus failed to meet its primary endpoint and clinical development was discontinued. In the wellness/grey market it is sold as a research chemical and used off-label for anti-aging and body-composition goals despite no clinically validated human dose for those uses.
MK-677 (ibutamoren, MK-0677, L-163,191) is an orally active, non-peptide small-molecule growth hormone secretagogue developed by Merck in the 1990s. It is a spiropiperidine ghrelin-receptor (GHSR-1a) agonist — not a peptide and not a SARM, though it is commonly misclassified as both in grey-market retail. Merck discontinued development after mixed efficacy and adverse metabolic / cardiovascular findings; it is not FDA-approved.
Ipamorelin
MK-677
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Ipamorelin
MK-677
No pricing data yet.
Check MK-677 prices →COA corpus from Disclosed Labs — independently tested batches only.
Ipamorelin
153
COAs
99.7%
Avg purity
17
Labs
MK-677
5
COAs
98.3%
Avg purity
3
Labs
Ipamorelin is among peptides under FDA review for the Category 1 (503A) list; if added, it would require a prescription to be compounded by registered 503A/503B pharmacies — not yet authorized. MK-677 remains research-only. In April 2026 the FDA removed 12 peptides from Category 2, which does not place them on the Category 1 list or authorize compounding. The FDA's Pharmacy Compounding Advisory Committee is advisory and meets July 23–24, 2026 to review nominations and make recommendations to the FDA.
The seminal preclinical characterization (Raun et al., 1998, PMID 9849822) established ipamorelin as the first GHRP-receptor agonist with GH-release selectivity comparable to GHRH, without raising ACTH or cortisol even at doses more than 200-fold above the ED50. Pharmacokinetic-pharmacodynamic modeling in healthy male volunteers (Gobburu et al., 1999, PMID 10496658) confirmed a roughly 2-hour half-life and dose-dependent GH response following IV infusion. The most advanced human study is Beck et al. (2014, PMID 25331030), a Phase 2, randomized, double-blind, placebo-controlled trial in 114 patients after bowel resection evaluating IV ipamorelin 0.03 mg/kg twice daily for postoperative ileus; the drug was well tolerated but did not separate from placebo on the primary endpoint (time to tolerance of solid food), and the sponsor (Helsinn/Nycomed) discontinued development. There are no completed registrational trials in adult GH deficiency, frailty, or body-composition indications. Ipamorelin is not FDA-approved for any indication. The 100–300 mcg dose range reflects community/compounding practice and is not clinically validated for anti-aging or body-composition use.
Key references
MK-677 has meaningful human data from Merck-sponsored Phase I/II trials. Murphy et al. (JCEM 1998, PMID 9467534) showed 25 mg MK-677 reversed nitrogen wasting during caloric restriction in healthy adults. Svensson et al. (JCEM 1998, PMID 9467542) reported ~40% IGF-1 elevation, increased fat-free mass, and higher energy expenditure over 8 weeks in obese men. Copinschi et al. (Neuroendocrinology 1997, PMID 9349662) documented improved slow-wave and REM sleep in young and older adults. Nass et al. (Ann Intern Med 2008, PMID 18981485) — the pivotal 2-year randomized trial in 65 healthy older adults — restored GH and IGF-1 to young-adult levels and increased fat-free mass, but produced modest fasting glucose elevation and insulin resistance. The Adunsky et al. Phase IIb hip-fracture trial (Arch Gerontol Geriatr 2011, PMID 21067829) was stopped early after a congestive-heart-failure safety signal (4/62 ibutamoren vs 1/60 placebo). Merck discontinued development. MK-677 is commonly mislabeled as a 'SARM' in grey-market retail — it is not; it is a ghrelin-receptor agonist and oral GH secretagogue. It has never been FDA-approved.
Ipamorelin and MK-677 are both in the Performance category and may have overlapping mechanisms. Researchers should review both profiles carefully, understand the mechanisms of action, and monitor the relevant biomarkers when combining compounds in the same class. As always, consult a licensed healthcare provider before making any decisions about combining research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
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Key references
Disclosed Labs