MK-677: sustained growth hormone elevation, and what the two-year trial found
The only orally active growth hormone secretagogue in common use, and the one with the most human trial data behind it. That data is worth reading carefully, because it is more informative than the marketing and less flattering.
Regulatory status. The app’s reference records this compound’s status as “Research”, reproduced here rather than summarised. It means no regulator has reviewed a manufacturer’s evidence for identity, purity, potency or safety in people for this compound, so nothing below is a marketing claim about a product you can buy.
Purity, identity and concentration are therefore unverified by anyone but whoever made the vial. The storage rule in the fact box below is general practice for this formulation rather than a specification for a particular product: General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
This page names no vendor, no clinic and no testing service, and there is no discount code anywhere on this site — the moment a page like this recommends where to buy, it stops being information.
- Also known as
- Nutrobal
- Class
- Growth hormone secretagogue
- Regulatory status
- Research
- Modelled half-life
- 24 h
- Time to peak
- 1 h
- Formulation
- Oral
- Storage
- Room temperature and dry, in the original container with whatever desiccant came in it, out of light.
- Once opened
- Unchanged once opened, as long as it stays dry.
- What ruins it
- Humidity is the real enemy — a bathroom cabinet is the worst place in the house for these.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
Continuous rather than pulsatile, and why that is the whole story
MK-677 is a non-peptide agonist at the ghrelin receptor — the same receptor ipamorelin and the GHRPs act at — with two properties that distinguish it from all of them: it is orally bioavailable, and the app models its half-life at about a day. A single daily tablet therefore produces sustained receptor occupancy rather than a discrete pulse.
That difference explains most of the compound's profile. Growth hormone is normally released in bursts against a suppressive background, and the burst pattern is thought to matter to how tissues respond. Continuous elevation of GH and IGF-1 is a different physiological state from amplified pulses, and it is the state associated with the fluid retention, joint symptoms and insulin resistance that show up in the trials. Whether it is also the state associated with the benefits people want is the question the human data was supposed to answer.
What the human trials actually found
Established clinical use The most informative study is a two-year randomised placebo-controlled trial in healthy older adults, published in 2008. Daily MK-677 raised growth hormone and IGF-1 into the range of healthy young adults and increased fat-free mass by roughly one and a half kilograms against placebo. It did not improve strength or physical function. Fasting glucose rose and insulin sensitivity fell.
That is an unusually clean result and it is rarely quoted in full. The compound does what it says at the level of the hormone and at the level of body composition, and the functional outcome that would justify the intervention did not follow. Two years is long enough to see it if it were there.
The compound has continued in pharmaceutical development for paediatric growth hormone deficiency, where the goal is diagnostic and therapeutic in people whose axis is genuinely underactive — a different question from raising a normal axis. It has never been approved for any indication, and the app records its status simply as research.
The effects that reliably turn up
Appetite stimulation is the most consistent, and it is mechanism rather than side effect: this is a ghrelin receptor agonist held at the receptor continuously. For anyone whose goal involves a caloric deficit, that is working against them, and it is the most common reason people stop.
Fluid retention, bloating and numbness or tingling consistent with carpal tunnel involvement follow from raised GH and are amount-dependent. The metabolic effect is the one that does not announce itself: reduced insulin sensitivity and rising fasting glucose were consistent findings in the trial data, which is why the app puts fasting glucose and HbA1c on the panel beside IGF-1. The HbA1c page covers why those two markers can disagree and what the disagreement means.
Prolactin and cortisol are on the app's panel for this compound and not for ipamorelin, reflecting the difference in selectivity and in exposure. None of this is a page's decision to weigh: a rising fasting glucose in someone taking a compound known to raise it is a conversation with a clinician, not a number to watch alone.
The curve, the accumulation ratio and the peak-to-trough figures have a page of their own: MK-677 / Ibutamoren half-life and steady state.
The dosing rows the app records
Off-label or community practice Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.
| Label | Amount | Route and frequency | Duration recorded |
|---|---|---|---|
| Starting | 10mg/day | Oral at bedtime | 4–8 weeks |
| Standard | 15–25mg/day | Oral at bedtime | 3–6 months, then break |
What the app monitors alongside it
The panel below is the app’s own monitoring note for MK-677 / Ibutamoren, verbatim. The analytes in it that have a page here are linked; those pages cover what each one measures, which assay produced it and how to read a trend.
- Monitoring panel
- IGF-1 every 6–8 weeks, fasting glucose, HbA1c, prolactin, cortisol, lipid panel. Baseline before starting.
Drawbacks and risks the app records
From the app's own entry, and it lines up closely with what the trials reported — which is unusual, and is the benefit of a compound that actually went through human study.
- Significant appetite stimulation
- Water retention and bloating
- Elevated cortisol and prolactin
- Can raise blood glucose — insulin resistance risk
- Numbness and tingling (carpal tunnel like)
- Not FDA approved
Questions people actually ask
Is MK-677 a SARM?
No. It is a growth hormone secretagogue acting at the ghrelin receptor and has nothing to do with androgen receptors. It is frequently sold and discussed alongside that class, which is a marketing category rather than a pharmacological one.
Why does it cause more side effects than injectable secretagogues?
Chiefly because of exposure rather than potency. A day-long half-life taken daily means continuous receptor occupancy and continuously elevated IGF-1; an injected peptide with a two-hour half-life produces a pulse and then clears. Continuous elevation is where fluid retention and insulin resistance come from.
Does the lean mass gain mean it works?
It means fat-free mass increased, which in the trial was accompanied by no improvement in strength or function. Fat-free mass includes body water, and growth hormone causes fluid retention. That is the most plausible reading of a lean-mass increase with no functional change, and it is why the functional endpoints matter.
How long does it take to clear?
The app models a day-long half-life, so about five days for a dose to clear and roughly the same for the level to plateau after starting. The half-life page has the curve and the accumulation figures.
Where the load-bearing numbers come from
Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.
- Two-year trial in healthy older adults
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults, Annals of Internal Medicine, 2008
- Ghrelin receptor agonism and oral bioavailability
- The compound’s published pharmacology from the 1990s development programme
- Continued development for paediatric growth hormone deficiency
- Ongoing clinical development of the same molecule under a different programme name
- Modelled half-life
- app.html’s TL_PK entry
A daily oral compound with a rising glucose signal is the case for logging the labs beside the dose. TherapyLog charts both on one timeline.
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