MK-677

Also known as: Ibutamoren, Nutrobal

Evidence Tier Cmed-high riskadvancednot approved

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.

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.

Research Details

Mechanism of Action

Ghrelin receptor agonist that stimulates endogenous GH release and increases downstream IGF-1.

Study Dose Range

Human studies and gray-market use commonly cite 10 mg to 25 mg orally once daily.

Administration Routes

oral

Onset / Timeline

GH rises acutely; IGF-1 and body-composition effects are tracked over weeks to months.

Expected Effects

Increased GH/IGF-1 signaling, appetite rise, and potential lean-mass increase in some human studies.

Adverse Effects

Edema, increased appetite, insulin resistance, elevated fasting glucose, joint discomfort, and possible cardiovascular safety concerns.

Contraindications

Use caution in diabetes, insulin resistance, edema-prone states, heart failure risk, and active malignancy.

Interaction Notes

Combining with other GH-axis compounds increases endocrine complexity and may worsen glucose control.

Related Goals

Muscle Growth & StrengthLongevity & Anti-AgingGH Axis Optimization

Known Interactions

caution with CJC-1295

Oral ghrelin-receptor agonism plus GHRH analog raises GH-axis complexity and glucose-monitoring burden.

caution with Sermorelin

MK-677 and sermorelin both push GH-axis signaling through different levers; treat as additive endocrine load.

caution with Tesamorelin

Combining ibutamoren with tesamorelin increases GH-axis burden and glucose-management uncertainty.

caution with Ipamorelin

MK-677 and ipamorelin both stimulate ghrelin-pathway signaling; redundancy and endocrine spillover risk rise.

caution with GHRP-2

Multiple ghrelin-receptor secretagogues in one stack increase endocrine noise and monitoring needs.

caution with GHRP-6

Redundant GHSR stimulation with added appetite and glucose-management downside.

caution with Hexarelin

Hexarelin plus MK-677 creates multiple GHS-pathway inputs with limited combination safety support.

Available From

No vendors currently listed for this peptide.

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Peptide Safety Basics

A practical risk framework covering route, evidence, product quality, and the mistakes that make gray-market research products look safer than they are.

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Frequently Compared

CJC-1295

Long-acting GHRH analogue studied in human trials for sustained GH/IGF-1 elevation.

Tier B

Sermorelin

GHRH(1-29) analogue that stimulates pulsatile GH secretion, historically used in clinical settings.

Tier B

Tesamorelin

FDA-approved GHRH analogue for HIV-associated lipodystrophy. Prescription only.

Tier A

Ipamorelin

Selective GHSR agonist profiled for more targeted GH release with less ACTH/cortisol spillover than earlier secretagogues.

Tier B-C

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.