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 Hexarelin and MK-677 — mechanism, dosing, side effects, legal status, and pricing.
Hexarelin (His-D-2MeTrp-Ala-Trp-D-Phe-Lys-NH2) is a synthetic hexapeptide growth hormone secretagogue developed by Mediolanum (Italy) in the 1990s. It is a potent ghrelin-receptor (GHSR-1a) agonist that also binds the CD36 scavenger receptor, giving it a cardioprotective signal distinct from other GHRPs. It is not FDA-approved for any indication and remains a research-only compound; its clinical development for GH deficiency and cardiac indications did not reach approval. A defining feature versus other GHRPs is rapid, pronounced tachyphylaxis with chronic daily dosing.
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.
Hexarelin
MK-677
Category
Legal Status
Mechanism
Dose Range
Route
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Hexarelin
MK-677
No pricing data yet.
Check MK-677 prices →COA corpus from Disclosed Labs — independently tested batches only.
Hexarelin
10
COAs
99.4%
Avg purity
4
Labs
MK-677
5
COAs
98.3%
Avg purity
3
Labs
Ghigo et al. (1994, PMID 8126144, JCEM) characterized hexarelin's GH-releasing activity across IV, SubQ, intranasal, and oral routes in healthy men, establishing it as a potent GH secretagogue. Rahim & Shalet (1998, PMID 10990150, Growth Horm IGF Res) demonstrated that twice-daily SubQ hexarelin in healthy elderly subjects caused ~45% attenuation of the GH AUC over 16 weeks, with partial recovery 4 weeks after discontinuation — the canonical human tachyphylaxis study. Bodart et al. (2002, PMID 11988484, Circulation Research) showed that hexarelin's cardiovascular action in perfused hearts is mediated by CD36 rather than GHSR-1a and is absent in CD36-null animals. Hexarelin has never been FDA-approved; grey-market use for body composition, recovery, or cardiac benefit is not clinically validated.
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.
Hexarelin (Hormone) and MK-677 (Performance) are in different categories and target different biological pathways. This is a common pattern in multi-compound research protocols. Researchers should monitor the biomarkers from both profiles and watch for interactions listed in each compound’s contraindications. Consult a licensed healthcare provider before combining any research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Frequency
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Half-life
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Lab Testing
Key references
Disclosed Labs