For laboratory research use only. Not for human consumption. Sold by Explicit SARMs solely as reference material for in-vitro and animal research by qualified professionals. Not evaluated by the FDA and not intended to diagnose, treat, cure or prevent any disease.
By Explicit SARMs Team
MK-677 (ibutamoren) is a non-peptide growth hormone secretagogue and ghrelin-receptor (GHS-R1a) agonist with a long published record. MK-777 (acetamoren) is the N-acetyl analog of ibutamoren. They are often confused because of their similar names, but they are different molecules, and no published data show that MK-777 behaves like MK-677. This page compares them for laboratory research only.
Side-by-side comparison
| MK-677 (ibutamoren) | MK-777 (acetamoren) | |
|---|---|---|
| Type | Non-peptide growth hormone secretagogue; GHS-R1a agonist | N-acetyl analog of ibutamoren |
| CAS | 159634-47-6 (free base); 159752-10-0 (mesylate) | 950841-87-9 |
| Formula / MW | C27H36N4O5S / 528.7 (free base) | C29H38N4O6S / approx. 570.7 |
| Published research | Extensive, starting with Patchett et al. 1995 (PMID 7624358) | No peer-reviewed pharmacology studies found |
| WADA | Named in section S2 | Not named; S2 covers related substances |
| Explicit SARMs formats | 90 capsules, 10mg each; liquid, 30ml at 30mg/ml | 90 capsules, 10mg each |
What the literature covers
MK-677 was designed at Merck and first described by Patchett et al. (1995) as a non-peptide growth hormone secretagogue acting at the ghrelin receptor. MK-777 has a CAS number but, as of October 2026, no peer-reviewed pharmacology papers, so any comparison of activity would be speculation.
Why the difference matters for researchers
Because MK-777 is a distinct molecule with its own CAS number and analytical profile, researchers should treat it as a separate reference compound rather than as a substitute for MK-677.
How Explicit SARMs tests these compounds
Our manufacturer tests it twice during production, and we use an independent third-party lab for purity testing. A COA is available on request.
Related research compounds
FAQ
Is MK-777 the same as MK-677?
No. MK-777 (acetamoren) is the N-acetyl analog of MK-677 (ibutamoren). It is a different molecule with a different CAS number, and no published data show that it behaves like MK-677.
Is MK-677 a peptide?
No. MK-677 is a non-peptide growth hormone secretagogue that acts at the ghrelin receptor (GHS-R1a).
What formats does Explicit SARMs supply?
MK-677 comes as 90 capsules at 10mg each and as a 30ml liquid at 30mg/ml. MK-777 comes as 90 capsules at 10mg each. All are for laboratory research use only.
How are they tested?
Our manufacturer tests it twice during production, and we use an independent third-party lab for purity testing. A COA is available on request.
Published research cited
- Patchett AA, et al. Design and biological activities of L-163,191 (MK-0677). Proc Natl Acad Sci U S A. 1995;92(15):7001-7005. PMID 7624358.