MK-677 (Ibutamoren) dosing evidence
MK-677 has never been approved by the FDA or any other regulator, for any indication. It went through a large clinical programme through the 1990s and 2000s and development was not carried to approval: the largest efficacy trials were negative, and a randomised phase IIb trial in elderly hip-fracture patients was terminated early over a congestive heart failure safety signal, with its authors concluding the compound had an unfavourable safety profile in that population. The evidence status is unusual for an unapproved compound. Randomised, placebo-controlled human trials stated their doses explicitly, at several dose levels and for durations of up to two years, so the published range below is quoted from those trials rather than converted or inferred. What does not exist is an approved label, a titration schedule, a maximum duration, or any authority that has weighed the benefit against the risk and found the balance acceptable. It is a small molecule taken by mouth, so nothing about it is reconstituted or injected.
Curated by Dosavy from published literature and regulator labels. Published 11 September 2026, last reviewed 11 September 2026. No clinician reviews this page.
What the evidence says
| Experience | Route | Range | Frequency |
|---|---|---|---|
| Beginner | Oral | 10–25 mg[1][2][3][4]One range only: MK-677 has no label and no titration schedule, so no beginner/maintenance/maximum split can be honestly reconstructed. 10 mg and 25 mg once daily are the two doses repeatedly compared head-to-head in placebo-controlled trials; 25 mg/day is the dose used in every long-duration study (2 years in healthy older adults, 12 months in Alzheimer disease, 18 months in postmenopausal osteoporosis, 24 weeks in hip fracture). Effect on GH and IGF-1 is dose-dependent across 2, 10 and 25 mg. Trials that examined sleep dosed at bedtime. | Once daily |
- BeginnerOral
Once daily
One range only: MK-677 has no label and no titration schedule, so no beginner/maintenance/maximum split can be honestly reconstructed. 10 mg and 25 mg once daily are the two doses repeatedly compared head-to-head in placebo-controlled trials; 25 mg/day is the dose used in every long-duration study (2 years in healthy older adults, 12 months in Alzheimer disease, 18 months in postmenopausal osteoporosis, 24 weeks in hip fracture). Effect on GH and IGF-1 is dose-dependent across 2, 10 and 25 mg. Trials that examined sleep dosed at bedtime.
Published ranges, reported as the literature states them and numbered to the sources at the foot of this page. Not a recommendation.
Unusually for an unapproved compound, MK-677 has genuine randomised, placebo-controlled human dosing evidence at multiple doses and durations up to two years, and the range below is quoted directly from those trials rather than inferred. What does NOT exist is an approved label, a titration schedule, a maximum recommended duration, or any authority that has judged the benefit-risk balance acceptable. The largest efficacy trials were negative and one was stopped for a heart-failure signal. Doses outside the recorded range have also been studied: 2 mg/day was sub-effective in healthy elderly subjects (PMID 8954023), 50 mg/day was given for 4 days to GH-deficient adults in a rising-dose study (PMID 9329386), and children with GH deficiency received weight-scaled 0.2 and 0.8 mg/kg/day for 7 days (PMID 11452249). None of those supports extending the adult range upward.
MK-677 (Ibutamoren) at a glance
- Category
- GH secretagogue
- Half-life
- Not established
- Routes
- Oral
- Regulatory status
- Not approved
- Also sold as
- Ibutamoren, Ibutamoren mesylate, MK-0677, MK 677, mk 677, L-163,191
Mechanism
An orally active, non-peptide spiropiperidine agonist at the growth hormone secretagogue receptor (GHS-R1a), a ghrelin mimetic. It amplifies the body's own pulsatile growth hormone release rather than replacing GH, so secretion remains subject to negative feedback. Daily oral dosing raises 24-hour mean GH, IGF-1 and IGF-binding-protein-3, with IGF-1 restored into the young-adult range in older adults. GH and prolactin rise most after the first dose and attenuate with repeated dosing; cortisol effects are transient.
Reconstitution
Not a lyophilised peptide. MK-677 is a small molecule taken by mouth. No reconstitution is required or appropriate.
Storage
Dispensed by compounding pharmacies as oral capsules or a liquid; follow the dispensing pharmacy's storage instructions. Research-chemical material sold online carries no validated storage specification.
Frequency in practice
Once daily. Trials that examined sleep gave the dose at bedtime.
Regulatory
Never approved by the FDA or any other regulator. Developed by Merck (as L-163,191 / MK-0677) through multiple phase 2 and phase 3-scale trials in the 1990s and 2000s; development was not carried to approval. It reaches users through telehealth prescribers, 503A compounding programmes and research-chemical vendors, none of which is an approved supply chain. Prohibited in competitive sport as a growth hormone secretagogue. It is detectable in hair for months after use and features in Court of Arbitration for Sport casework (PMID 40882886).
What to know before anything else
Not approved for human use. Despite a large clinical programme including a 563-patient 12-month trial, no regulator has ever approved MK-677 for any indication.
CARDIAC SAFETY SIGNAL: a randomised phase IIb trial in 123 elderly hip-fracture patients was terminated early because of a congestive heart failure safety signal, and the authors concluded that 'MK-0677 has an unfavorable safety profile in this patient population' (PMID 21067829).
Impairs glucose handling. In obese young men, 25 mg daily left fasting glucose and insulin unchanged but produced impaired glucose tolerance on OGTT at both 2 and 8 weeks (PMID 9467542). A review of this drug class identifies reduced insulin sensitivity and raised blood glucose as its main recurring safety concern (PMID 28400207).
Target engagement is not benefit. In 563 patients with mild-to-moderate Alzheimer disease, 25 mg daily raised serum IGF-1 by roughly 73% at 12 months and had no effect at all on any measure of disease progression (PMID 19015485).
Raises IGF-1 substantially and keeps it raised. Long-term cancer-incidence and mortality data for GH secretagogues do not exist; the review that says they are 'well tolerated' says in the same breath that this data is needed (PMID 28400207).
Causes weight gain that is not all lean tissue. Over 1 year in healthy 60-81 year olds, body weight rose 2.7 kg on MK-677 versus 0.8 kg on placebo; fat-free mass increased by 1.1 kg but limb fat also increased more than on placebo (PMID 18981485).
Stimulates appetite strongly via the ghrelin receptor, a mechanism, not a side effect, and one that works directly against a fat-loss goal.
Case reports describe serious events in recreational users stacking MK-677 with SARMs, including atraumatic splenic rupture (PMID 42064485) and adverse shifts in bone density, lipids, liver enzymes and testosterone (PMID 36303408). Causality is not established, but neither combination has been studied.
Reviewed interactions
These are the pairs Dosavy holds reviewed, cited data on. A combination that is not listed here has not been assessed, which is not the same as being safe.
- Cautionwith Semaglutide
These pull in opposite directions. MK-677 is a ghrelin-receptor agonist (ghrelin is the hunger hormone), and in obese young men 25 mg daily produced impaired glucose tolerance on OGTT at both 2 and 8 weeks. A GLP-1 agonist is taken to suppress appetite and improve glycaemic control, so MK-677 works against both of its endpoints.[5]
GHS-R1a agonism increases appetite and, via raised growth hormone, reduces insulin sensitivity; semaglutide suppresses appetite and enhances glucose-dependent insulin secretion.
- Cautionwith Tirzepatide
Same opposition as with any incretin agonist: MK-677 raises appetite and degrades glucose tolerance, which is the opposite of what tirzepatide is prescribed to do. If you are running both, the fasting glucose and HbA1c you would otherwise attribute to the tirzepatide are being pulled on from two directions.[5]
MK-677 acts at the ghrelin receptor to stimulate appetite and raises growth hormone, which reduces insulin sensitivity; tirzepatide agonises GIP and GLP-1 receptors to do the reverse.
- Cautionwith Sermorelin
A daily oral ghrelin-receptor agonist plus a GHRH analogue stimulates growth hormone release through two separate pathways, producing more than the sum of the parts. MK-677 already keeps GHS-R1a engaged continuously, so the sermorelin is layering a second stimulus onto a receptor system that is not resting between doses.
Sermorelin acts on the pituitary GHRH receptor; MK-677 on GHS-R1a. The two converge synergistically on the somatotroph.
- Cautionwith Tesamorelin
GHRH analogue plus oral ghrelin-receptor agonist: synergistic on growth hormone output, and with a prescription drug on one side of it. Tesamorelin's approved dose and its IGF-1 monitoring expectations were set for monotherapy; MK-677 raises IGF-1 independently and also impairs glucose tolerance, which tesamorelin's label already flags as something to watch.[5]
Both raise growth hormone and therefore IGF-1, tesamorelin through the GHRH receptor and MK-677 through GHS-R1a.
MK-677 (Ibutamoren) questions
Is MK-677 a SARM or a steroid, and how does it actually work?
It is neither. MK-677 is an orally active, non-peptide spiropiperidine that agonises the growth hormone secretagogue receptor GHS-R1a, which is the ghrelin receptor. It mimics ghrelin rather than supplying a hormone, so it amplifies your own pulsatile growth hormone release and that release stays subject to normal negative feedback. Daily oral dosing raises 24-hour mean growth hormone, IGF-1 and IGF-binding-protein-3. Growth hormone and prolactin rise most after the first dose and attenuate with repeated dosing; cortisol effects are transient.
Why was MK-677 never approved, given how large the trials were?
Because the large trials did not show a benefit and one showed a harm. In 563 patients with mild-to-moderate Alzheimer disease, 12 months of daily dosing raised serum IGF-1 by roughly 73% and had no effect on any measure of disease progression. A randomised phase IIb trial in 123 elderly hip-fracture patients was terminated early for a congestive heart failure safety signal. Its original developer took it through multiple phase 2 and phase 3-scale trials and development was not carried to approval. It now reaches people through telehealth prescribers, compounding programmes and research-chemical sellers, none of which is an approved supply chain, and it is prohibited in competitive sport.
Should MK-677 be taken in the morning or at night?
The trials dosed it once daily, and the ones that examined sleep gave the dose at bedtime. That is the whole of what the published record establishes about timing. No trial compared morning against evening dosing for body composition, appetite or glucose handling, so anything stated about which is better for those outcomes is preference rather than evidence.
Does MK-677 affect blood sugar?
Yes, and this is its most consistently reproduced metabolic effect. In obese young men, daily dosing left fasting glucose and insulin unchanged but produced impaired glucose tolerance on an oral glucose tolerance test at both 2 and 8 weeks, so a normal fasting reading does not rule it out. A review of this drug class identifies reduced insulin sensitivity and raised blood glucose as its main recurring safety concern. Anyone taking a GLP-1 receptor agonist should note the two pull in opposite directions on exactly this endpoint.
Is the weight gained on MK-677 muscle or water?
The trial data says it is not all lean tissue. Over one year in healthy adults aged 60 to 81, body weight rose 2.7 kg on MK-677 against 0.8 kg on placebo, fat-free mass increased by 1.1 kg, and limb fat also increased more than on placebo. So more than half of the weight gained was something other than fat-free mass, and fat was part of it. The library records no trial measuring strength or muscle cross-section on this compound, so whether the fat-free mass gain does anything is not answered here.
Why does MK-677 increase appetite so much?
Because that is the receptor it was built to hit. GHS-R1a is the ghrelin receptor, and ghrelin is the hormone that signals hunger, so strong appetite stimulation is the mechanism working rather than a side effect of it. That matters for what people take it for: it works directly against a fat-loss goal, and combined with impaired glucose tolerance it makes an unintended gain in fat mass a predictable outcome rather than a surprise.
What is still unknown about taking MK-677 long term?
The thing most worth knowing is absent rather than reassuring. MK-677 raises IGF-1 substantially and keeps it raised, and long-term cancer-incidence and mortality data for growth hormone secretagogues do not exist; the review describing them as well tolerated says in the same sentence that this data is needed. Case reports describe serious events in recreational users combining MK-677 with SARMs, including an atraumatic splenic rupture and adverse shifts in bone density, lipids, liver enzymes and testosterone. Causality is not established in either report, and neither combination has been studied. It is also detectable in hair for months after use.
Every number above, and where it came from
5 sources, numbered where they are used. Each one links to the paper or the label itself, not to a summary of it.
- [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.
The Journal of clinical endocrinology and metabolism · 1996 · Randomized, double-blind, placebo-controlled trial · n=32
- [2]Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group.
Journal of bone and mineral research · 1999 · Pooled randomized, double-blind, placebo-controlled trials · n=187
- [3]Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.
Annals of internal medicine · 2008 · 2-year double-blind, randomized, placebo-controlled, modified-crossover trial · n=65
- [4]Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial.
Neurology · 2008 · Multicenter double-blind randomized controlled trial · n=563
- [5]Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure
The Journal of Clinical Endocrinology and Metabolism · 1998 · Randomised double-blind placebo-controlled trial
The rest of the math
- Reconstitution calculatorThe full version of the tool above, with syringe barrel sizes and IU conversion.
- Vial longevityHow many doses a vial holds and the date it runs out.
- Cost per doseVial price against doses drawn, so two vial sizes can be compared honestly.
- Half-life and decayFirst-order clearance, time to steady state, and what remains at a given hour.
Same class as MK-677 (Ibutamoren)
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A calculator answers once and forgets. Dosavy keeps the concentration you mixed, the doses you actually took, and a reminder for the next one, with the same evidence labels you see on this page.