The Oral Secretagogue
MK-677
Also known as Ibutamoren
At a glance
- What it is
- An oral GH secretagogue producing sustained rather than pulsatile elevation.
- Evidence
- Small human studiesHow the tiers workCopinschi et al. (1996) studied a 7-day course of MK-677 on 24-hour GH profiles, IGF-1 and adrenocortical function in humans, and Nass et al. (2008) ran two years in 65 healthy older adults. Why this tier
- Half-life
- Not established in available literature
- Routes
- Oral
- Category
- Growth hormone
- WADA
- Prohibited (S2.2.4)
Putting MK-677 on a schedule, with the vial it comes from and a log of each dose, happens in the app: Claritide for iPhone.
Why this tier
Copinschi et al. (1996) studied a 7-day course of MK-677 on 24-hour GH profiles, IGF-1 and adrenocortical function in humans, and Nass et al. (2008) ran two years in 65 healthy older adults. Both are real human data, and both point the same way: the GH axis responds, and glucose control gets worse. FDA separately cites a randomised hip-fracture trial terminated early over a potential congestive-heart-failure signal. This is the compound in the library with the strongest safety case against it, not the weakest evidence base.
What it is
MK-677, also called ibutamoren, is a growth hormone secretagogue taken orally rather than injected. Our material distinguishes it from the injectable peptides on one important axis: it produces sustained GH elevation rather than the pulsatile pattern that GHRH analogs and GHRPs preserve. Two randomised trials put its studied dose at 10–25 mg a day, with 25 mg the one carried furthest, and the same trials are where the rising fasting glucose comes from.
How it works
MK-677 is an orally active growth hormone secretagogue: it raises GH and IGF-1 without injection, which is its main practical appeal. Our sources characterise the release pattern as sustained rather than pulsatile. That distinction matters: the injectable secretagogues in this library are valued specifically because they preserve the body's natural bursts of GH release and the somatostatin feedback brake that governs them, whereas continuous elevation is the pattern associated with receptor desensitisation.
Commonly researched ranges
- Randomised trial doses10–25 mg
Two randomised trials converge here: Chapman 1996 compared 2, 10 and 25 mg/day, and Nass 2008 ran 25 mg/day for two years in 65 healthy older adults. 25 mg is the dominant studied dose. Read it with the metabolic result attached, because it came from the same trials: fasting glucose rose by about 5 mg/dL, insulin sensitivity fell, and cortisol rose by roughly 47 nmol/L. The GH axis responding and glucose control worsening are one finding, not two.
| Phase | Amount | Frequency | Timing | Note |
|---|---|---|---|---|
| Randomised trial doses | 10–25 mg | Once daily | Not established in available literature | Two randomised trials converge here: Chapman 1996 compared 2, 10 and 25 mg/day, and Nass 2008 ran 25 mg/day for two years in 65 healthy older adults. 25 mg is the dominant studied dose. Read it with the metabolic result attached, because it came from the same trials: fasting glucose rose by about 5 mg/dL, insulin sensitivity fell, and cortisol rose by roughly 47 nmol/L. The GH axis responding and glucose control worsening are one finding, not two. |
- Cycle guidance
- Not established in available literature
- Goals
- Muscle, Sleep, Recovery
Where this sits with the FDA
503A Category 2 and 503B Category 2 · bulk substances that may present significant safety risks
The only compound in this library with a live FDA “significant safety risk” designation under both compounding pathways. FDA cites a randomised placebo-controlled trial in hip-fracture recovery that was terminated early over a potential congestive-heart-failure safety signal.
Last change · 29 September 2023 · Added to the 503A Category 2 list on 29 September 2023.
Primary sourceHow it got here
- 29 December 2022
FDA placed MK-677 in 503B Category 2.
- 29 September 2023
FDA placed MK-677 in 503A Category 2.
WADA status
Named on the 2026 List under S2.2.4, growth hormone secretagogues. Prohibited at all times, and separately on the US Department of Defense Prohibited Dietary Supplement Ingredients List.
There is nothing to mix
Not applicable. None of the published routes for this compound take a diluent, so there is no concentration to calculate and no beyond-use window to track.
Week by week
Not established in available literature.
Side effects
Common
- Raised fasting glucose and reduced insulin sensitivity
- Fluid retention and joint discomfort
Rare
- Transaminitis (raised liver enzymes)
- Splenic rupture (confounded case report)
- Congestive heart failure signal
Contraindications and interactions
Do not use if
- Active cancer: GH promotes cell proliferation
- Do not combine with other GH secretagogues or exogenous GH without medical guidance
- Heart failure or reduced cardiac reserve: FDA cites a hip-fracture trial terminated early over a potential congestive-heart-failure signal
- Diabetes or impaired glucose tolerance: the two-year randomised trial recorded rising fasting glucose and falling insulin sensitivity
- Liver disease: a 2025 case report describes transaminitis that resolved after stopping
- Drug-tested competition: on the WADA Prohibited List and on the US Department of Defense Prohibited Dietary Supplement Ingredients List
Interactions
- Other GH secretagogues and exogenous GHcaution
Cumulative GH-axis load with unpredictable hormonal effects.
- Diabetes medicationcaution
Fasting glucose rises and insulin sensitivity falls, which moves the target the medication is aimed at.
- Cancer therapiesavoid
Growth-promoting pathways.
Absence from this list does NOT mean safety. It means lack of research.
Storage and cost
- Storage
- Our sources do not publish storage guidance for MK-677. It is taken orally and is not reconstituted.
- Cost
- Not established in available literature
MK-677 in full
Limited coverage
MK-677 appears in the growth-hormone comparison table on our tesamorelin page and in the source list of our sleep guide. We hold no dedicated page, no dosing figures and no timeline for it.
The safety profile is the exception, and it is unusually well documented for a compound with no approval: two human trials, three published safety findings and a live FDA designation. Those are on this page in full.
What our sources do say
MK-677, ibutamoren, is a growth hormone secretagogue that works orally. Everything else in the GH section of this library is injected, so that is its distinguishing practical feature and the reason it stays popular.
The mechanistic caveat is the one our comparison table flags: the GH release pattern is described as sustained, not pulsatile.
That single word matters more than it looks. Tesamorelin, CJC-1295, ipamorelin and the GHRPs are all valued because they work through the pituitary and preserve the body's natural bursts of GH release, with the somatostatin feedback brake left intact. Continuous elevation is the pattern our tesamorelin page associates with receptor desensitisation and with the risk profile of injected growth hormone. MK-677 sits closer to that end.
Evidence
Copinschi et al. (1996) studied a seven-day course in humans, measuring 24-hour GH profiles, IGF-1 and adrenocortical function. Our comparison table rates the evidence as moderate, with "oral convenience" as the noted advantage.
The dose, and what came with it
The dosing row on this page is not community practice. It is two randomised trials: Chapman 1996 compared 2, 10 and 25 mg a day, and Nass 2008 ran 25 mg a day for two years in 65 healthy older adults. On evidence alone that makes MK-677 one of the better-documented compounds in this library, and the row is 10 to 25 mg once daily because that is the band those trials actually used.
Read it with what the same trials measured. Fasting glucose rose by around 5 mg/dL, insulin sensitivity fell, and cortisol rose by roughly 47 nmol/L. The GH axis responding and glucose control getting worse are one result, not two, and no cycle length has ever been shown to avoid the second half.
Our own published material still states no frequency or cycle length for it, and we do not fill that in from elsewhere.
The safety side is where the asymmetry sits. There is one sourced dose band on this page and five sourced adverse findings: a trial stopped early over a congestive-heart-failure signal, a two-year randomised trial recording worse glucose control, a hepatotoxicity case report, a confounded splenic rupture, and a Department of Defense listing. Every GH-axis caution applies on top of that: active cancer as a contraindication, and no stacking with other GH-modulating compounds without medical guidance.
Sources
- 1Copinschi et al., 1996 · Effects of a 7-day treatment with MK-677 on 24-hour GH profiles, IGF-I, and adrenocortical function, JCEM 81(8)
- 2Nass et al., 2008 · Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults, Ann Intern Med 149(9). Two years, n=65, 25 mg/day.
- 3BMJ Case Reports, 17 July 2025 · transaminitis associated with MK-677 in a healthy adult
- 4US Department of Defense Operation Supplement Safety, 23 February 2024 · MK-677 (ibutamoren)
- 5FDA · Certain bulk drug substances for use in compounding that may present significant safety risks
- 6Chapman et al., 1996 · 2, 10 and 25 mg/day oral MK-677 in healthy older adults, the dose-comparison trial (dose review, 2026-08-17)
- 7Nass et al., 2008 · PubMed record for the two-year 25 mg/day trial (dose review, 2026-08-17)
- 8University of Maryland M-CERSI · FDA-commissioned ibutamoren review (dose review, 2026-08-17)
Every record in this library is free to read, and it stays free. Your own schedule, vials and log live in the app: Claritide for iPhone.