Peptide education
MK-677 (ibutamoren)
Ibutamoren · MK-677 · MK-0677 · Ibutamoren mesylate · LUM-201
MK-677, also called ibutamoren and studied as LUM-201, is a small molecule that stimulates growth hormone release. It is not a peptide and is not growth hormone itself.
An older-adult trial found more fat-free mass but no demonstrated improvement in strength or function. A separate Alzheimer trial did not slow measured progression. A separate study measured growth in selected children with growth hormone deficiency. FDA identifies ibutamoren as unapproved.
Overview
Quick answer
Raising growth hormone or IGF-1 is a measurable biological response, not proof that strength, function, or a disease outcome improves.
Is MK-677 a peptide?
No. Ibutamoren is a nonpeptide growth hormone secretagogue.
Does it improve strength?
In one trial of healthy older adults, fat-free mass increased but strength and function did not improve significantly. The trial was not adequately powered to settle functional outcomes.
What are the main safety concerns?
The older-adult trial reported higher fasting glucose and lower insulin sensitivity, as well as appetite, edema, and muscle pain. FDA describes a potential heart-failure signal in a separate hip-fracture trial.
Evidence
Evidence snapshot
In the older-adult trial, strength and function did not significantly improve.
IGF-1 rose, but the measured clinical scales did not differ significantly from placebo.
An analysis of a placebo-controlled trial reported higher annualized height velocity with LUM-201 in children with growth hormone deficiency.
FDA also warned about ibutamoren found undeclared in a specific product.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Verdict |
|---|---|---|---|
| More IGF-1 means better physical performance. | Fat-free mass increased in one older-adult trial, but strength and function did not significantly improve. | The compound stimulates growth hormone release and raises IGF-1. | A biomarker or body-composition change is not proof of improved performance. |
| It slows Alzheimer disease. | A trial randomized 563 participants, of whom 416 completed treatment and assessments at 12 months; its clinical scales did not show a significant benefit. | Serum IGF-1 increased during treatment. | The clinical outcome did not support this claim in the studied population. |
Bottom line
Main takeaway
This is a nonpeptide drug candidate, not a proven general wellness treatment.
Glucose effects and the FDA heart-failure signal matter alongside any proposed use.
Separate hormone endpoints from body composition and patient-level outcomes.
Identity
What it is
Ibutamoren is an oral nonpeptide secretagogue studied for its effects on the growth hormone and IGF-1 axis.
Research
Research evidence
Placebo-controlled studies measured both biomarkers and clinical outcomes. A separate analysis reported increased growth velocity in selected children with growth hormone deficiency; a phase 3 study is ongoing. Findings depend on the population and endpoint and do not establish a benefit for other uses.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| Older-adult body-composition trial | 71 healthy adults aged 60 to 81 randomized; 65 completed the first year | Randomized, double-blind, placebo-controlled modified crossover | Oral MK-677 | At 12 months, fat-free mass changed by 1.1 kg with MK-677 and -0.5 kg with placebo; strength and function did not significantly improve. | Six participants did not complete the first year. The study lacked adequate power for functional endpoints and enrolled healthy older adults. | Randomized comparison, with limited functional precision |
| Alzheimer disease trial | 563 people with mild to moderate disease randomized; 416 completed treatment and assessments at 12 months | Multicenter, randomized, double-blind comparison with placebo | Oral MK-677 | IGF-1 increased, but measured clinical and cognitive scales did not differ significantly over 12 months. | Not all randomized patients completed treatment and assessments; results apply to this disease population and the scales assessed. | Randomized clinical outcome study |
| Pediatric growth hormone deficiency analysis | 68 treatment-naive, prepubertal children who completed 6 months in a randomized trial | Post hoc analysis of a placebo-controlled trial | Oral ibutamoren studied as LUM-201 | Mean annualized height velocity over 6 months was 6.0 and 6.9 cm per year in the 0.4 and 0.8 mg/kg per day groups, versus 4.5 cm per year with placebo. | This per-protocol analysis involved a small, selected population and does not establish long-term outcomes or an approved treatment. | Pediatric randomized-trial analysis with limited generalizability |
Use context
Reported use context
These are trial methods, not a suggested regimen or an approved use.
Study and label context
The trial used 25 mg once daily; its primary body-composition comparison was at 12 months.
This was a research protocol, not a recommendation for strength, aging, or body composition.The trial assigned 25 mg once daily or placebo for 12 months.
Clinical scales did not show a significant benefit; this is not a treatment recommendation.Selected children received 0.4 or 0.8 mg/kg per day or placebo for 6 months.
This was a research protocol in a selected pediatric population, not an approved or recommended regimen.Cautions
Safety and unknowns
- Fasting glucose increased and insulin sensitivity decreased in the older-adult study.
- Appetite, transient lower-leg edema, and muscle pain were reported in that study.
- FDA notes a potential congestive heart-failure signal in a separate hip-fracture trial; its applicability to other populations is uncertain.
- Long-term safety and effects in people outside the studied populations remain uncertain.
Product quality
Product identity and quality
FDA found undeclared ibutamoren in one product marketed for children. The finding is specific to that product.
Ingredient identity
A product label may not establish what it contains.
Source and quality
A research report does not verify the contents or quality of a separate product.
Mechanism
How it is proposed to work
Ibutamoren stimulates the body's growth hormone system and can increase IGF-1.
The secretagogue receptor is distinct from the growth hormone-releasing hormone receptor.
Details
Technical details
Sources
References
- 1.
PubMed. Oral ibutamoren mesylate in children with growth hormone deficiency
doi:10.1067/mcp.2001.116514 PMID:11452249
A short hormone-response study that identifies ibutamoren as a nonpeptide secretagogue.
- 2.
PubMed. Oral ghrelin mimetic and body composition in healthy older adults
doi:10.7326/0003-4819-149-9-200811040-00003 PMID:18981485
Randomized modified-crossover trial; 71 participants were randomized and 65 completed the first year.
- 3.
PubMed. MK-677 and Alzheimer disease progression in a randomized trial
doi:10.1212/01.wnl.0000335163.88054.e7 PMID:19015485
A placebo-controlled trial with clinical endpoints in people with mild to moderate Alzheimer disease.
- 4.
PubMed. LUM-201 and growth in children with growth hormone deficiency
doi:10.1210/jendso/bvab030 PMID:33982679
Post hoc analysis of a randomized placebo-controlled trial; 68 selected children completed six months.
- 5.
ClinicalTrials.gov. Phase 3 study of LUM-201 in pediatric growth hormone deficiency
NCT06948214
Ongoing randomized placebo-controlled study; registration does not establish efficacy or approval.
- 7.
FDA. FDA bulk substances that may present significant safety risks
FDA discusses ibutamoren mesylate and a potential heart-failure signal in a hip-fracture trial.