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 ACE-031 and MK-677 — mechanism, dosing, side effects, legal status, and pricing.
ACE-031 (ramatercept) is a soluble fusion protein of the activin receptor IIB (ActRIIB) extracellular domain and human IgG1 Fc, developed by Acceleron Pharma as a myostatin/activin ligand trap for muscle-wasting disorders. Clinical development was HALTED in 2011 after unexpected vascular adverse events (epistaxis, telangiectasia) attributed to off-target BMP-9/10 inhibition. NOT FDA-approved; all further development was terminated. Now sold only as a grey-market research chemical. WADA-prohibited (myostatin inhibitor).
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.
ACE-031
MK-677
Category
Legal Status
Mechanism
Dose Range
Route
Frequency
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
ACE-031
1 vendor lists this, but none clear the trust bar (score ≥70) yet.
Check ACE-031 prices →MK-677
No pricing data yet.
Check MK-677 prices →COA corpus from Disclosed Labs — independently tested batches only.
ACE-031
1
COAs
99.8%
Avg purity
1
Labs
MK-677
5
COAs
98.3%
Avg purity
3
Labs
Phase 2 in ambulatory boys with Duchenne muscular dystrophy was terminated early in 2011 after unexpected nose-bleeds and telangiectasia were observed (attributed to off-target BMP-9/10 neutralization); published results later showed no significant 6MWT benefit vs. placebo in the truncated trial (Campbell et al., Muscle & Nerve, 2017; PMID 27462804). A single-ascending-dose Phase 1 study in healthy postmenopausal women (Attie et al., Muscle & Nerve, 2013; PMID 23169607) showed dose-dependent modest lean-mass increase but also the same vascular signal. Acceleron formally discontinued ACE-031 in 2013 and pivoted to other ActRII programs. No FDA approval; development TERMINATED for vascular safety. WADA-prohibited.
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.
Key references
ACE-031 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.
Dosing Notes
Half-life
Side Effects
Contraindications
Lab Testing
Disclosed Labs