MK-677 (Ibutamoren)

No. Ibutamoren is a small, non-peptide molecule. It gets filed with peptides because it switches on the same ghrelin receptor as GHRP-6 and ipamorelin, and because it is used in the same GH protocols. Being a small molecule is why it works as a pill.

10 to 25 mg once a day is the usual range. Almost every adult trial used 25 mg. Many people start at 10 mg to see how the hunger and water retention go, and some stay there. Guides say going above 25 mg adds side effects without much more IGF-1.

Bedtime is the common pick: you sleep through the worst of the hunger, and the sleep studies dosed at bedtime. If evening hunger is a problem, guides move it to the morning or split it, 12.5 mg morning and 12.5 mg at night.

About 4 to 6 hours, measured in beagles. The effect lasts much longer: IGF-1 stays raised for up to 24 hours after a single dose, which is why many guides loosely call it a 24-hour half-life. Either way, once a day is enough.

Yes, modestly. Over 2 years, fasting glucose rose about 5 mg/dL and insulin sensitivity fell. A 4-week study in older adults saw fasting glucose go from 5.4 to 6.8 mmol/L at 25 mg. That matters most for anyone already near prediabetes.

It adds lean mass, but the trials did not show strength gains. In older adults on 25 mg, fat-free mass rose 1.1 kg in a year while the placebo group lost 0.5 kg, with no change in strength or function. Obese men also gained fat-free mass in 8 weeks without losing fat.

In small studies, yes. Young adults on 25 mg at bedtime got about 50% more deep (stage IV) sleep and more than 20% more REM sleep. Older adults got nearly 50% more REM sleep.

The signal is in frail patients. A trial in elderly hip-fracture patients on 25 mg was stopped early when a few developed congestive heart failure, and FDA cites that trial for its Category 2 listing. The 2-year trial in healthy older adults reported no serious adverse effects. Water retention is the likely link.

Real but usually temporary. In the 2-year trial, more appetite was the top side effect and faded within a few months; leg swelling was mild and transient. Guides say the hunger peaks in the first 2 to 4 weeks and is gentler at 10 mg.

Nobody has proven it. Common cycles are 8 to 16 weeks on, or 12 to 16 on with 4 to 8 off. The longest trial ran 2 years straight at 25 mg and IGF-1 stayed up. Glucose is the usual reason people take breaks.

Both are sold. Capsules come in 10, 12.5 and 25 mg; liquids are usually 25 mg/mL. Buyers question how stable some liquids are. Most products are the mesylate salt (624.8 g/mol vs 528.67 for the free base), and labels rarely say which form the milligrams refer to.

It is not FDA approved. FDA put ibutamoren mesylate on its compounding Category 2 list over heart-failure risk, and its December 2025 warning letters say ibutamoren cannot be sold as a dietary supplement. It is still in drug trials as LUM-201.

Sports tests, yes. WADA's 2026 list names ibutamoren (MK-677) among growth hormone secretagogues, banned in and out of competition.

No. In 563 patients with mild to moderate Alzheimer's, 25 mg a day for 12 months raised IGF-1 by 72.9% but did not slow the disease on any measure.

Yes. Lumos Pharma runs it as LUM-201 for children with GH deficiency: Phase 2 compared 0.8 to 3.2 mg/kg a day with GH injections, and a Phase 3 trial at 1.6 mg/kg a day is recruiting.