MK-677

What it is

MK-677 (ibutamoren, also known as MK-0677) is an orally active, non-peptide small molecule that binds the ghrelin receptor (GHSR1a) and works as a growth hormone secretagogue: it stimulates the pituitary to release growth hormone in a pulsatile pattern and raises IGF-1. Unlike injectable growth hormone releasing peptides, it is taken by mouth. Merck developed it and tested it in randomized, placebo-controlled human trials for several conditions, none of which led to approval. In healthy older adults, 25 mg per day for up to two years increased fat-free mass but did not improve strength or physical function, and it raised fasting blood glucose while reducing insulin sensitivity. A 563-person, 12-month trial in mild-to-moderate Alzheimer's disease found no cognitive benefit despite a large rise in IGF-1. A hip-fracture recovery trial was stopped early after a congestive heart failure signal appeared in the treatment group. MK-677 is not approved by the FDA or any major regulator for any use, and in 2024 an FDA advisory committee voted against allowing pharmacies to use it in compounding. Development continues under the name LUM-201 for pediatric growth hormone deficiency. Outside of trials, it is sold online as an unregulated research chemical.

Dose ranges

Study-backed ranges carry a source you can open. Community ranges are widely reported but not clinically established - treat them as what people do, not as advice.

Storage

Common stacks

Interactions & cautions

MK-677 has never been approved, so no formal human drug-drug interaction trials have been published. The clearest signal from the available placebo-controlled trials is metabolic: in the dose-finding study (Chapman et al., 1996), fasting glucose rose from 5.4 to 6.8 mmol/L after 4 weeks of 25 mg/day; in the 2-year trial (Nass et al., 2008), fasting glucose rose by about 0.3 mmol/L (5 mg/dL) on average and insulin sensitivity decreased. This is relevant to people with diabetes, prediabetes, or other insulin-resistance risk, and to anyone taking glucose-lowering medication, since MK-677's effect on glucose could work against it, though no formal interaction study with a specific diabetes drug has been done. Fluid retention/edema and appetite increase were also common in the same trials. Separately, a randomized hip-fracture-recovery trial (Adunsky et al., 2011) was stopped early after a safety signal of congestive heart failure appeared in a limited number of MK-677 recipients, in a frail elderly population; whether this generalizes to healthier or younger users has not been studied. In 2024, an FDA advisory committee (the Pharmacy Compounding Advisory Committee) voted against adding ibutamoren mesylate to the list of bulk substances compounding pharmacies may use, so it remains outside routine, regulated clinical and pharmacy channels.

Questions people ask

Sources

1. [1]Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects PMID 8954023studyDose-ranging trial (2, 10, or 25 mg/day oral MK-677) in healthy elderly subjects showing a dose-dependent rise in 24-hour GH and IGF-1, and a significant increase in fasting glucose (5.4 to 6.8 mmol/L) after 4 weeks at 25 mg/day.
2. [2]MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism PMID 9467534study25 mg/day oral MK-677 during a 7-day caloric-restriction period reversed diet-induced negative nitrogen balance in healthy adults and was reported as generally well tolerated short-term.
3. [3]Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial PMID 18981485study2-year, randomized, placebo-controlled, modified-crossover trial of 25 mg/day oral MK-677 in 65 adults aged 60-81: increased fat-free mass (P<0.001), raised fasting glucose and lowered insulin sensitivity, raised cortisol, and the most frequent side effects were appetite increase, transient mild leg edema, and muscle pain, with no serious adverse effects and no improvement in strength or function.
4. [4]Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial PMID 19015485study563-patient, 12-month randomized trial of 25 mg/day oral MK-677 in mild-to-moderate Alzheimer's disease: IGF-1 rose 60.1% at 6 weeks and 72.9% at 12 months, but there was no significant benefit on cognitive or functional outcomes (CIBIC-plus, ADAS-Cog, ADCS-ADL, CDR-sob).
5. [5]MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study PMID 21067829studyPhase IIb trial of 25 mg/day MK-0677 in 123 elderly hip-fracture patients: IGF-1 rose significantly (P<0.001) and gait speed improved, but the trial was terminated early after a safety signal of congestive heart failure in a limited number of patients, and the authors concluded MK-0677 has an unfavorable safety profile in this population.
6. [6]Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males PMID 32257855reviewPeer-reviewed review reporting an oral elimination half-life of 5 to 6 hours for ibutamoren, summarizing trial doses (2/10/25 mg and 25 mg regimens), and noting elevated prolactin, fasting glucose, insulin, and fluid retention as reported adverse effects.
7. [7]NCATS Inxight Drugs: IbutamorenreferenceNIH drug-development database confirming ibutamoren is investigational only (never approved), reached Phase 2, and was developed by Merck for indications including fibromyalgia, muscle wasting in chronic kidney disease, Alzheimer's disease, and hip fracture, with development discontinued; provides CAS number and molecular formula.
8. [8]PubChem Compound Summary for CID 178024, IbutamorenreferenceChemical identity: IUPAC name, molecular formula C27H36N4O5S, molecular weight 528.7, and (via the linked synonyms record) CAS number 159634-47-6 and synonyms including MK-677, MK-0677 forms, and L-163,191.
9. [9]DailyMed: AX PHARMACEUTICAL CORP - ibutamoren mesylate powderregulatoryConfirms the only DailyMed listing found for ibutamoren mesylate is a bulk ingredient for animal drug compounding (not an FDA-approved human drug product), 99 g/100 g white powder, and the label includes no storage instructions.
10. [10]PCAC votes against four nominated bulk drug substancesreferenceTrade-press report confirming the FDA's Pharmacy Compounding Advisory Committee voted against adding ibutamoren mesylate (along with three other substances) to the Section 503A bulk drug substances list for human compounding.
11. [11]ClinicalTrials.gov: A Phase 3 Study of LUM-201 in Children With Growth Hormone Deficiency (NCT06948214)regulatoryRegistry record confirming an active, recruiting Phase 3 trial of oral LUM-201 (the current development code for ibutamoren) for treatment-naive pediatric growth hormone deficiency, sponsored by Lumos Pharma; confirms the compound remains unapproved and in development for this indication.
12. [12]MK 677: Your Ultimate Ibutamoren ResourcecommunityCommunity/health-content source reporting a typical self-directed dosing range of 10 to 25 mg/day, noting MK-677 is not FDA-approved, and describing water retention and insulin-sensitivity concerns anecdotally.