- oral
MK-677 (Ibutamoren)
Ibutamoren Mesylate (MK-0677, L-163,191)
MK-677 (Ibutamoren) at a glance
FDA category 2How studies gave it
Swallowed
Evidence on this page
3 peer-reviewed papers, published 2008 to 2011
FDA compounding lists
FDA put it on the list of bulk substances that may carry significant safety risks.
What it is
A non-peptide, orally active small molecule that acts as a potent agonist of the growth hormone secretagogue receptor (GHS-R1a), mimicking endogenous ghrelin to stimulate pulsatile GH and IGF-1 release. MK-677 has been studied in multiple human randomized controlled trials across indications including sarcopenia, diet-induced catabolism, Alzheimer's disease, hip fracture recovery, and sleep quality, but has not received FDA approval for any indication.
It is discussed in biohacking communities in the context of GH optimization, body composition, sleep improvement, and recovery, and is notable for its oral bioavailability and ~24-hour effective half-life.
Published research
MK-677 has been evaluated in multiple human RCTs: a 2-year sarcopenia trial in healthy older adults (Nass et al. 2008, PMID 18981485, n=65), diet-induced catabolism reversal (Murphy et al. 1998, PMID 9467534), a large Alzheimer's trial (Sevigny et al. 2008, PMID 19015485, n=563), hip fracture recovery (Adunsky et al. 2011, PMID 21067829, terminated early), and sleep quality improvement (Copinschi et al. 1997, PMID 9349662).
Key findings include sustained GH/IGF-1 elevation with oral once-daily dosing, increased lean mass, but also insulin resistance and glucose intolerance concerns with extended use. Lumos Pharma's Phase 2 OraGrowtH trials for pediatric GHD have met primary endpoints. Community dosing ranges are derived from clinical trial protocols.
What the terms on this page mean12 termsHide
- peptide
- A short chain of amino acids, the building blocks of proteins.
- agonist
- A molecule that binds a receptor and switches it on.
- GH
- Growth hormone, released by the pituitary gland, involved in growth and tissue repair.
- receptor
- A docking point on a cell. A molecule that fits it can switch a process on or off inside that cell.
- endogenous
- Made by the body itself, rather than given from outside.
- IGF-1
- Insulin-like growth factor 1, made largely in the liver in response to GH, and the marker most GH studies measure.
- randomised controlled trial
- A trial that assigns people to treatment or control by chance, which is what lets it separate an effect from luck.
- bioavailability
- The share of a dose that reaches the bloodstream intact.
- half-life
- The time it takes for a drug's concentration in the blood to fall by half. It does not, by itself, determine a dosing schedule.
- PMID
- The identifier PubMed gives a paper. It is what makes a citation checkable.
- Phase 2
- A mid-size trial testing whether the substance does anything useful.
- clinical trial
- A study that tests something in people under a written plan, with results recorded.
Compounding status
FDA category 2- FDA lists it as
- Ibutamoren mesylate
- Applies to
- Compounders under section 503A; 503B
- Added
- 503A: September 29, 2023; 503B: December 29, 2022
- What that means
- FDA has identified significant safety risks relating to the use of these substances in compounding pending further evaluation and does not intend to adopt the enforcement policy it applies to category 1 substances.
Source: Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA. Content current as of 2026-04-22; read 2026-09-05. This describes what a compounding pharmacy may supply. It is not advice about your own use.
Also given oral
- NoopeptNoopept (Omberacetam, GVS-111, N-Phenylacetyl-L-prolylglycine Ethyl Ester)Not on either FDA list
- SemaglutideSemaglutide (acylated GLP-1(7-37) analog)Not on either FDA list
- BPC-157 ArginateBPC-157 Di-L-Arginine Salt (Bepecin Arginate)Not on either FDA list
- DihexaN-hexanoic-Tyr-Ile-(6)-aminohexanoic amide (PNB-0408)Nomination withdrawn
- GHRP-6Growth Hormone Releasing Peptide-6FDA category 2
- KPVLysine-Proline-Valine (α-MSH C-terminal tripeptide)Nomination withdrawn
Where this came from3 referencesHide
Each one was resolved at PubMed and confirmed to be the work this page cites. Author, title, journal and year come from the PubMed record, not from the page text.
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial
Nass R, et al.. Annals of internal medicine (2008). PMID 18981485.
- MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study
Adunsky A, et al.. Archives of gerontology and geriatrics (2011). PMID 21067829.
- Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial
Sevigny JJ, et al.. Neurology (2008). PMID 19015485.
About this page
Reviewed 2026-08-11. This page reports what published studies and FDA documents say. It carries no dose, cycle length or stack, and it does not tell you whether a substance is appropriate for you. Side-effect reports circulating on forums are self-reported rather than measured, so they are not republished here.
See the editorial policy for how corrections are handled.