MK-677
Also known as: Ibutamoren, Nutrobal, MK677
MK-677 (also called Ibutamoren or Nutrobal) is an oral ghrelin-mimetic small molecule in the Growth Hormone Secretagogue class. MK-677, also called ibutamoren, is an orally bioavailable non-peptide agonist at growth hormone secretagogue receptor 1a.
For research use only.
Key Facts
- CAS
- 159752-10-0
- Molecular Weight (MW)
- 624.8 g/mol
- Half-life
- ~24 hours
- FDA status
- Not Approved
- Administration Route
- Oral
- Frequency
- Once daily
- Last updated
- Aug 30, 2026
- Reviewed
- Aug 30, 2026
- Targets
- GHSR
Vendor price snapshot
Price per mg is list price divided by vial size in milligrams when both are known from public vendor listings. Peptide Library does not sell peptides. Confirm live prices on the vendor site.
- Vendors listing this peptide
- 4
- Listed offers
- 4
- Price per mg range
- $5.60–$12.00/mg
Research summary
Oral non-peptide GH secretagogue (ibutamoren) that raises GH and IGF-1. Not FDA-approved. WADA S2 names ibutamoren (MK-677).
Peptide Library's MK-677 profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Protocol
- Dosage Range
- Research literature often 10–25 mg orally once daily — not an approved label
- Frequency
- Once daily
- Cycle
- Research-dependent
- Administration Route
- Oral
- Reconstitution Guide
- Oral — no reconstitution
- Timing Notes
- Educational catalog only — not medical advice
Not yet checked against primary sources
These figures are compiled from earlier reference material. They have not been verified against FDA labelling, registered trials or published literature, no citation is attached to them, and none of them is a recommended dose. MK-677 is queued for dosage evidence review.
Compare reported doses across the whole librarySequence & molecular data
| Molecular formula | C28H40N4O8S2 |
|---|---|
| Molecular weight | 624.8 g/mol |
| CAS number | 159752-10-0 |
| Half-life | ~24 hours |
| Appearance | Oral capsule / powder |
| Formulation | Oral capsule |
| PubChem CID | 6450830 |
| FDA UNII | R90JB6QJ2B |
| ChEMBL | CHEMBL2105872 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
MK-677, also called ibutamoren, is an orally bioavailable non-peptide agonist at growth hormone secretagogue receptor 1a. It mimics ghrelin at the pituitary and hypothalamus, producing a sustained increase in growth hormone and IGF-1 with a half-life supporting once-daily dosing — the property that distinguishes it from injectable peptide secretagogues. Because it activates the ghrelin receptor it also increases appetite. The recognised metabolic consequences follow from sustained GH elevation: reduced insulin sensitivity and increased fasting glucose, together with fluid retention and oedema. It has been studied extensively but is not approved for any indication.
Origin
Synthetic spiropiperidine small molecule.
Targets
Studies
- MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism
- Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue
- Hepatotoxicity induced by MK-677
- Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report
Regulatory & research status
MK-677 is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Availability | Research-Only |
| WADA (sport) | Banned in Sport |
| Library classification | Research-Only |
Benefits
Potential Side Effects
Side Effects
- Hunger
- Edema
- Insulin resistance
- Lethargy
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
MK-677: frequently asked questions
What is MK-677?
Oral non-peptide GH secretagogue (ibutamoren) that raises GH and IGF-1. Not FDA-approved. WADA S2 names ibutamoren (MK-677).
How does MK-677 work?
MK-677, also called ibutamoren, is an orally bioavailable non-peptide agonist at growth hormone secretagogue receptor 1a. It mimics ghrelin at the pituitary and hypothalamus, producing a sustained increase in growth hormone and IGF-1 with a half-life supporting once-daily dosing — the property that distinguishes it from injectable peptide secretagogues.
Is MK-677 FDA approved?
No. MK-677 is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What is the half-life of MK-677?
Reported half-life for MK-677 is ~24 hours. Half-life describes how long the compound persists in circulation, not how long any effect lasts, and published figures vary with route of administration, formulation and the population studied.
Is MK-677 banned in sport?
MK-677 is recorded here as prohibited in sport. Athletes subject to anti-doping rules should check the current WADA Prohibited List directly, since it is revised annually and classifications change.
What peptides are similar to MK-677?
Compounds most often compared with MK-677 include Ipamorelin, GHRP-6, GHRP-1 and Pralmorelin (GHRP-2). They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- WADA Prohibited List 2026External reference
- MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism — J Clin Endocrinol Metab, 1998External reference
- Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue — Clin Chim Acta, 2026External reference
- Hepatotoxicity induced by MK-677 — BMJ Case Rep, 2025External reference
- Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines — Basic Clin Pharmacol Toxicol, 2025External reference
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report — Exp Physiol, 2022External reference
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Aug 30, 2026 · Version 2
This MK-677 profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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