MK-677
Also known as Ibutamoren · Nutrobal
Oral ghrelin-receptor agonist used as a GH secretagogue in research and bodybuilding markets.
FDA Safety Flag
The FDA has identified this substance as one that may present significant safety risks when used in compounding, including concerns about immunogenicity, impurity characterization, and/or insufficient safety information.
WADA S2
This substance falls under WADA S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics). If you are subject to anti-doping rules, this category of substances is prohibited at all times.
Not Approved
This substance is not approved by any major regulatory body for human therapeutic use. All information is derived from preclinical research, limited clinical studies, or off-label contexts.
Evidence visual
MK-677 evidence and risk matrix
advanced researcher fit
Evidence
Tier C
Risk
med high
Regulatory
not approved
WADA
S2
FDA
flagged
Route
oral
Mixed evidence profile. Useful for comparison, not a standalone protocol decision.
Overview
MK-677, also known as ibutamoren, is an oral ghrelin-receptor agonist that raises GH and IGF-1. Human studies exist in GH-deficiency and aging contexts, but it is not FDA-approved and has meaningful safety questions, including fluid retention, glucose effects, and FDA-cited cardiac risk concerns. WADA explicitly bans ibutamoren under S2 growth-hormone secretagogues.
Decision path
Where MK-677 fits in the research path.
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Peptide research path
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Research Details
Ghrelin receptor agonist that stimulates endogenous GH release and increases downstream IGF-1.
oral
Human studies and gray-market use commonly cite 10 mg to 25 mg orally once daily.
Increased GH/IGF-1 signaling, appetite rise, and potential lean-mass increase in some human studies.
GH rises acutely; IGF-1 and body-composition effects are tracked over weeks to months.
Use caution in diabetes, insulin resistance, edema-prone states, heart failure risk, and active malignancy.
Edema, increased appetite, insulin resistance, elevated fasting glucose, joint discomfort, and possible cardiovascular safety concerns.
Combining with other GH-axis compounds increases endocrine complexity and may worsen glucose control.
Cost at a glance
No reliable cycle cost estimate yet. We need cleaner listing price and pack-size data before showing a trustworthy number.
Age, sex, and monitoring
Life-stage fit
Most often discussed for younger and midlife adults, but metabolic and fluid-retention risks narrow the fit quickly with age.
Best fit age ranges: 25-34, 35-44
55-64
Later-life GH-axis stimulation becomes harder to justify without clear medical supervision.
65+
Cancer, cardiovascular, and glucose-management risk make this a poor fit for most older adults.
Sex-specific note
The endocrine burden is real for both sexes, but the evidence is not strong enough to support different male and female recommendation logic beyond reproductive caution.
female
Avoid in pregnancy or active conception planning because GH-axis manipulation lacks reproductive safety data.
Monitoring burden
highGH-axis and glucose-related monitoring burden is materially higher than for simpler wellness compounds.
Baseline labs and checks
fasting glucose or HbA1c, CMP, IGF-1, blood pressure and weight baseline
Follow-up cadence
More frequent early follow-up, then reassessment every few months if continued.
Red flags
- rapid edema
- worsening glucose control
- numbness or carpal-tunnel-like symptoms
Known Interactions
Oral ghrelin-receptor agonism plus GHRH analog raises GH-axis complexity and glucose-monitoring burden.
MK-677 and sermorelin both push GH-axis signaling through different levers; treat as additive endocrine load.
Combining ibutamoren with tesamorelin increases GH-axis burden and glucose-management uncertainty.
MK-677 and ipamorelin both stimulate ghrelin-pathway signaling; redundancy and endocrine spillover risk rise.
Multiple ghrelin-receptor secretagogues in one stack increase endocrine noise and monitoring needs.
Redundant GHSR stimulation with added appetite and glucose-management downside.
Hexarelin plus MK-677 creates multiple GHS-pathway inputs with limited combination safety support.
Information provided for educational and research reference only. Not medical advice. Not for diagnosing, treating, curing, or preventing disease. Products referenced are labeled Research Use Only (RUO) by vendors; not for human or veterinary use.
Sources and review notes
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks - U.S. Food and Drug Administration - accessed 2026-05-15
Used for FDA compounding-risk context and peptide safety flags.
- The Prohibited List - World Anti-Doping Agency - accessed 2026-05-15
Used for athlete-facing WADA risk and peptide-class restrictions.
- Peptide therapeutics: current status and future directions - PubMed / Nature Reviews Drug Discovery - accessed 2026-05-15
Used for broad peptide-therapeutics background and evidence framing.
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