MK-677 (also known as MK-677 or Ibutamoren) is a performance-enhancing peptide studied for its effects on growth hormone, muscle gain, sleep. Oral ghrelin receptor agonist boosting GH/IGF-1 and sleep quality. Causes insulin resistance and glucose issues. Not FDA-approved, development discontinued.
Ibutamoren (MK-677) is a potent, long-acting, orally-active, selective non-peptide agonist of the ghrelin receptor (GHS-R1a) and growth hormone secretagogue. It mimics ghrelin's action by binding to receptors in the hypothalamus and pituitary gland, increasing growth hormone secretion by 50-97% and significantly elevating IGF-1 levels while preserving natural pulsatile GH secretion patterns. Clinical trials in elderly populations demonstrated significant increases in lean body mass (1.1 kg gain vs 0.5 kg loss with placebo over 12 months), improved bone mineral density, and enhanced markers of bone formation.
Overview
Notable for dramatically improving sleep quality with 20-50% increases in REM sleep and 50% increases in slow-wave sleep.
However, ibutamoren consistently impairs glucose metabolism, causing fasting blood glucose elevation, decreased insulin sensitivity, and increased HbA1c in multiple trials, leading to dose reductions or discontinuation.
One clinical trial was terminated due to serious adverse events including cardiovascular concerns and congestive heart failure cases in elderly patients.
Not FDA-approved and development appears discontinued due to safety concerns, particularly cardiovascular risks and metabolic effects.
Common side effects include increased appetite, water retention, insulin resistance, and potential increased cancer risk from elevated IGF-1.
Recommended 8-12 week cycles at 10-25mg daily, typically taken before bed for sleep benefits.
As a growth hormone secretagogue, it is prohibited by the World Anti-Doping Agency (WADA) both in and out of competition.
Mechanism of action
Oral ghrelin receptor agonist that raises growth hormone and IGF-1. Increases lean mass, bone density, and deep sleep. Causes insulin resistance and elevated blood sugar.
Reported effects
Effects reported in the literature and from preclinical models include:
- Preliminary data have been reported for oral ibutamoren as a growth hormone secretagogue in children with partial growth hormone deficiency. [4] Anecdotal
- A single 10 mg oral dose was incorporated into human hair at 1.3 pg/mg, and a 600 mg regimen over 90 days gave 224 pg/mg, which established a minimal detectable dose for doping control. [1] Anecdotal
- Ibutamoren was the most frequently reported compound in suspected illegal sport-performance products analysed by laboratories in 13 European countries. [2] Preclinical
- Most of the seized sport-performance samples were assumed to contain active doses, and some were overdosed, so consumer health risks cannot be neglected. [2] Preclinical
- Recent use with the SARM RAD-140 preceded one case of atraumatic splenic rupture, where IGF-1 pathway effects were raised only as a speculative contributing factor. [3] Anecdotal
Evidence grades: FDA approvedApproved (non-US)Phase IIIPhase IIPhase IPreclinicalAnecdotal
Dosage and administration
Low dose
- 10-15mg daily (ideal for sleep, longevity, first-time users)
Moderate dose
- 20-25mg daily (clinical trial standard, body recomposition)
High dose
- 30mg+ daily (advanced users, not recommended due to side effects)
Timing
- Before bed: Maximizes sleep benefits, reduces daytime hunger
- Morning: Increases appetite throughout day (useful for bulking)
Cycle duration
- 8-12 weeks recommended, up to 16 weeks for intermediate
Half
- life: 24 hours (once daily dosing sufficient)
General
- Monitor fasting glucose and insulin sensitivity during use
Natty status
MK-677 is classified as not natty. It appears on the WADA prohibited list and is banned by major natural bodybuilding federations.[5] Use of this compound places the athlete in the enhanced category rather than the natural category in competitive contexts.
Research
The peptide has been the subject of 9 studies and reference works collected on this site. Additional bibliography is in § External links below.
Related compounds
Other peptides in this catalogue with overlapping mechanisms or status:
References
- ^ Hair detection study for doping control
- a b Illegal medicines analysis
- ^ Spontaneous Splenic Rupture in a Patient With Recent Use of Performance-Enhancing Compounds: A Case Report and Literature Review.
- ^ New directions in growth hormone treatment in children. Recent review
- a b World Anti-Doping Agency. (2026). Prohibited List 2026.
External links
- Wikipedia article
- Elderly trial on body composition effects
- Diabetes case report
- Ghrelin pathway therapeutic potential review
- Treatment of Pediatric Growth Hormone Deficiency With Oral Secretagogues Revisited.
- MK-677 Capsules — commercial
This page was last updated on August 4, 2026, at 00:36 (UTC).
Research last reviewed on August 4, 2026.
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