What is Ibutamoren (MK-677)?
The short answer
Ibutamoren, or MK-677, is a lab-made pill that is studied in research on growth hormone.
What it is
Non-peptide ghrelin-receptor agonist studied in research on GH and IGF-1.
What people look into
Muscle and exercise, aging, sleep
- 6 sources
- Status as of
- How we source
- Ellum doesn't sell peptides.
Get updates on Ibutamoren (MK-677)
What it is
- Type
- Oral GH secretagogue (non-peptide)
- Also known as
- ibutamoren mesylate
- How it works
- Non-peptide ghrelin-receptor agonist studied in research on GH and IGF-1.
Regulatory status
Not FDA-approved How we label status
As of October 4, 2026, Ibutamoren (MK-677) is not FDA-approved for any use and is not on FDA's 503A bulks list.
- Federal (FDA)
- Not FDA-approved
- 503A compounding
- Category 2 (since 2023-09-29); 503B Category 2 (since 2022-12-29); not on 216.23 as of 2026-10-07 (as of October 7, 2026)
- PCAC history
- 2024-10-29: against 1-13-0; FDA staff: against
- WADA 2026
- S2.2.4
Timeline
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Timeline table
| Date | What happened | Source |
|---|---|---|
| FDA debarment notice in the Federal Register lists MK-677 among drug ingredients imported in the conduct behind the underlying conviction. | Federal Register, event of February 14, 2022, on federalregister.gov | |
| FDA warning letter states that products marketed as SARMs, including ibutamoren (MK-677), are unapproved new drugs. | FDA, event of July 6, 2022, on fda.gov | |
| Federal Register notice of an FDA Pharmacy Compounding Advisory Committee meeting lists ibutamoren mesylate among bulk drug substances under consideration for the 503A bulks list. | Federal Register, event of September 18, 2024, on federalregister.gov | |
| FDA warning letter states that products marketed as SARMs, including MK-677 (ibutamoren), are unapproved new drugs. | FDA, event of December 12, 2025, on fda.gov | |
| FDA warning letter states that laboratory analysis found undeclared ibutamoren mesylate (MK-677), an ingredient not approved by FDA, in two products. | FDA, event of December 19, 2025, on fda.gov | |
| FDA list of bulk drug substances nominated under section 503A, updated May 14, 2026, places ibutamoren mesylate in category 2, raise significant safety risks. | FDA, event of May 14, 2026, on fda.gov |
US enforcement actions
1 US enforcement action, in 2023.
Actions by US federal and state agencies whose documents name Ibutamoren (MK-677). Each row links to the government's own document.
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US enforcement actions table
| Date | Agency | Action | Document |
|---|---|---|---|
| FDA | Warning letter | FDA document, warning letter, June 12, 2023, on fda.gov |
References
Sources as of October 4, 2026
- FDA: www.fda.gov/media/94155/download
- FDA: www.fda.gov/media/185412/download
- FDA: www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
- FDA warning letter, June 12, 2023
- WADA: www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
- eCFR: www.ecfr.gov/current/title-21/chapter-I/subchapter-C/part-216/subpart-B/section-216.23