What it is
MK-677, also called ibutamoren (development code MK-0677), is an orally active, non-peptide growth hormone secretagogue. It mimics ghrelin at the GHS-R1a receptor to raise the body’s own growth hormone (GH) and IGF-1. Unlike the injectable peptides in this library, it is a small molecule taken by mouth. It was investigated by Merck across several indications but was never approved for human use, and development was discontinued. It is not a licensed medicine and is not a legal dietary supplement ingredient.
What people use it for
Reported goals are sustained GH and IGF-1 elevation for body composition, recovery, sleep and appetite. Because it is oral and long-acting, people use it as a once-daily alternative to injectable secretagogues. Be aware that the human trial record, while larger than for most peptides here, was strong enough on safety signals to stop Merck advancing it.
Typical dose range
The widely used community dose is 25 mg once daily, commonly taken at bedtime. Clinical trials used 25 mg daily in healthy older adults. Some users run lower (for example 10 to 12.5 mg) to reduce side effects, especially water retention and appetite. Higher is not better here: the side effect burden rises and there is no benefit case for pushing the dose. Dosing is oral so no reconstitution is involved, but if you are also running injectable peptides alongside it, the calculator can help with those: Peptide Calculator - Reconstitution & Dosage | Buy Peptides UK
Half-life and frequency
MK-677 has a long half-life of roughly 24 hours, which is why a single daily oral dose produces sustained, measurable GH and IGF-1 elevation without injections. Once-daily dosing is standard.
Reconstitution (typical)
Not applicable. MK-677 is an oral compound (powder, capsule or liquid), so there is no bacteriostatic water reconstitution step. If a product is supplied as a raw powder, accurate measurement of the small daily amount is the main practical challenge, and a milligram scale is more relevant than a syringe.
Storage
Keep it cool, dry and out of direct light, in a sealed container. Liquid or suspended preparations should follow the supplier’s storage guidance. Keep well away from children given the appetite and metabolic effects.
Common side effects
This is the compound in this set with the clearest documented downsides, so be specific:
- Increased appetite (reported in about 67 percent of treated older adults versus 36 percent placebo in trial data).
- Water retention and mild oedema (about 44 percent versus 27 percent placebo).
- Transient muscle pain (about 33 percent versus 9 percent placebo).
- Fatigue or lethargy.
- Elevated fasting glucose and reduced insulin sensitivity. Studies report increases in blood glucose, reduced insulin sensitivity and rises in HbA1c, which is a meaningful concern for anyone with blood sugar issues.
Most important: at least one clinical programme was stopped early over a heart failure signal. In an elderly hip fracture trial (Adunsky and colleagues), congestive heart failure occurred more often in the ibutamoren group (about 6.5 percent versus 1.7 percent placebo), which led to early termination and contributed to Merck discontinuing development. That is a genuine red flag, not a rumour.
Stacking and co-solubility
Not a solubility question, since it is oral. People sometimes run it alongside injectable secretagogues or GHRH analogs, but stacking multiple GH-raising compounds compounds the same risks (glucose disturbance, IGF-1 elevation, fluid retention). The conservative approach is not to layer several GH-raising agents at once.
Evidence grade
Small human RCTs exist (for example Nass and colleagues 2008 in older adults, plus the hip fracture and Alzheimer’s programmes). They show MK-677 reliably raises GH and IGF-1 (for example IGF-1 up roughly 84 percent versus 17 percent placebo in one hip fracture study), but functional benefit endpoints often failed, and a congestive heart failure signal appeared in the elderly. So: efficacy at raising IGF-1 is well established, real-world functional benefit is not, and there is a documented safety concern.
Honest unknowns
- Long-term cardiovascular safety in younger, healthy users is not established, and the heart failure signal in older adults is unexplained.
- Long-term metabolic impact (glucose, insulin sensitivity, HbA1c) of years of use is not characterised.
- Whether intermittent or lower dosing meaningfully reduces these risks is not proven.
- Product purity and actual content vary by source, which affects the real dose taken.
Research use only. Not medical advice. 18+.