MK-677 (Ibutamoren)
Ibutamoren · Nutrobal
An orally active, long-acting GH secretagogue — convenient but notably raises appetite and blood sugar.
Class
Non-peptide ghrelin receptor agonist / GH secretagogue
Half-life
~24 hours
Evidence
Randomized human trials
Randomized human trials
Supported by randomized controlled trials in humans. Several compounds at this level are FDA-approved for specific indications.
Overview
MK-677 is not a peptide — it is an orally bioavailable small molecule that activates the same ghrelin receptor as ipamorelin. Its long half-life means once-daily oral dosing sustains elevated GH and IGF-1 around the clock, which is both its main convenience and its main drawback.
It has been studied in humans more than most compounds here, including trials in the elderly and in muscle-wasting states. A two-year study in older adults showed sustained IGF-1 elevation and increased lean mass, but also a signal toward reduced insulin sensitivity and raised fasting glucose.
The trade-off profile is distinctive: strong appetite stimulation (useful for bulking, unwanted for cutting), noticeable water retention, and the most pronounced glucose effect of the GH-axis compounds. It is WADA-prohibited and failed to gain approval despite reaching phase 2 for several indications.
How it works
- Agonises the GHS-R1a ghrelin receptor, driving sustained GH and IGF-1 elevation.
- Orally active with ~24-hour half-life — sustained elevation rather than a pulse.
- Strongly stimulates appetite via the ghrelin pathway.
- Sustained GH signalling produces more insulin resistance than pulsatile secretagogues.
What the research shows
Researched effects
- Sustained IGF-1 elevation and increased lean body mass over 12–24 months in older adults
- Improved nitrogen balance in catabolic states
- Improved sleep architecture (increased REM and slow-wave sleep) in some studies
- Increased bone turnover markers
Limitations & what it won't do
- Reduced insulin sensitivity and elevated fasting glucose in longer trials.
- Significant water retention and appetite increase.
- Lean-mass gains did not consistently translate to functional strength improvements in the elderly trial.
- WADA-prohibited; not FDA-approved.
Dosing protocols
These ranges reflect published trials and community protocols. They are reference information, not a prescription. Doses are per injection unless noted.
Commonly used oral protocol
10–25 mgHigher doses increase water retention and glucose effects without proportional benefit. Many use 10–12.5 mg.
Administration
Not an injectable reconstitution compound
Side effects
Common
- Marked appetite increase
- Water retention and puffiness
- Lethargy or grogginess (often improves)
- Numbness/tingling in hands
- Vivid dreams
Serious / rare
- Reduced insulin sensitivity and elevated fasting glucose
- Fluid retention worsening heart failure
- Elevated IGF-1 with theoretical tumour-promotion risk
Contraindications & interactions
Do not use if you have
- Active cancer or current oncology treatment
Sustained IGF-1 elevation; contraindicated during active malignancy.
- Pregnant, breastfeeding, or trying to conceive
No pregnancy safety data.
- Cardiovascular disease
Marked fluid retention makes established heart failure an unacceptable risk.
Use caution if you have
- Type 2 diabetes or insulin resistance
MK-677 has the strongest glucose-worsening effect of the GH-axis compounds. Monitor closely or avoid.
- Type 1 diabetes
Significant insulin coordination required.
- High blood pressure
Fluid retention can raise blood pressure.
- Past cancer diagnosis (in remission)
IGF-1 elevation warrants oncology clearance.
- Carpal tunnel or nerve compression
Fluid retention frequently aggravates carpal tunnel.
Medication interactions
- cautionInsulin — Meaningfully raises glucose; insulin needs often increase. Close monitoring required.
- monitorSulfonylureas — Opposing glucose effects complicate control.
- cautionGrowth hormone (rhGH) — Redundant and additive on IGF-1.
- cautionCorticosteroids — Additive glucose elevation and fluid retention.
What to monitor
- Fasting glucose and HbA1c — the key marker for this compound
- IGF-1 levels
- Blood pressure and weight/fluid status
Commonly combined with
References
- Nass R et al. — Effects of MK-677 on body composition in older adultsAnnals of Internal Medicine 2008;149:601-611
- Chapman IM et al. — MK-677 (an orally active GH secretagogue) reverses diet-induced catabolismJ Clin Endocrinol Metab 1998
Research & educational information only — not medical advice.
You must be 18 or older to use this site. The peptides described are presented as research chemicals intended for research purposes only. Most are not approved by the FDA for human use. Dosing ranges reflect what has appeared in the scientific literature or community protocols and are not prescriptions. Nothing here replaces evaluation by a licensed physician who knows your full medical history.
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