Gathering the record
Relay is organizing the evidence and source boundaries.
Oral ghrelin-receptor agonist small molecule
Ibutamoren is an oral small molecule that activates the ghrelin receptor and increases pulsatile growth hormone and IGF-1.
60-Second Overview
Start with what it is, why it matters, what research has shown, and what remains unknown. The science follows after the orientation.
Start here. These four answers explain why the compound matters before the page introduces the deeper science.
Ibutamoren, often called MK-677, is an investigational oral small molecule that activates a ghrelin-related signal and increases the body's own growth hormone and IGF-1.
Researchers have studied whether sustained hormone changes can affect body composition, recovery after fracture, sleep physiology, or physical function without injecting growth hormone itself.
A one-year randomized trial in healthy older adults increased growth-hormone measures and fat-free mass but did not improve strength or physical function. Other controlled studies produced mixed condition-specific findings and reported appetite, swelling, muscle discomfort, or worsened glucose measures.
Whether any group gains durable functional benefit that outweighs glucose, edema, appetite, cardiovascular, and possible proliferative risks remains unresolved. Ibutamoren is not approved, and biomarker change is not automatically clinical benefit.
The research depth, routes, studies, and primary sources below explain how Relay knows—and where the evidence stops.
Research context
Published research has investigated this compound using the following study designs.
These records explain what researchers did. They are not instructions, recommendations, or a transferable protocol.
A one-year controlled trial investigated ibutamoren in healthy older adults, measuring hormone levels, body composition, strength, function, and safety.
Reported study administration—not a recommendation.
Research at a glance
Evidence depth, confidence, and route context explain how Relay knows—not what anyone should do.
Multiple controlled human studies with mixed clinical outcomes and unresolved long-term benefit-risk.
Research depth describes how large and mature the overall record is. It does not tell you whether the results were positive.
Whether any population gains durable functional benefit that outweighs glucose, edema, appetite, cardiovascular, and other longer-term risks.
Confidence describes how reliable and consistent the conclusions are. It can be high for one outcome and low for another.
The strongest evidence type shows what the best-supported conclusions are actually based on.
Human findings are more directly relevant than animal or laboratory results, but they still apply only to the populations and outcomes studied.
Route-specific record
These are exposures used in cited research for a specific route and population—not an instruction for an individual.
Half-life describes how long it takes the measured amount in the body to fall by half. It is not a dosing recommendation.
Evidence can change by administration method. Findings from one route should not automatically be applied to another.
Evidence boundary: The selected older-adult population and study size cannot resolve uncommon or very long-term harms. Higher hormone levels and fat-free mass did not produce improved strength or physical function. Amounts shown describe cited research exposure—not a dosage recommendation.
Detailed evidence
Start with the strongest supported conclusion and its main uncertainty. Claim-level records below show how the evidence changes by question, population, route, formulation, and study design.
A one-year randomized trial in healthy older adults increased GH/IGF-1 and fat-free mass without improving strength or physical function.
This is the strongest supported conclusion in the current human evidence—not a summary of every claim made about the compound.
Whether any population gains durable functional benefit that outweighs glucose, edema, appetite, cardiovascular, and other longer-term risks.
Keeping the main uncertainty visible prevents an early or promising finding from looking more settled than it is.
Questions people bring to the evidence
Research questions—not promises of benefit.
This is the strongest human-evidence boundary in the current record.
Mechanistic findings explain biological plausibility; they do not establish a human outcome.
Relay keeps this uncertainty visible rather than converting it into a prediction.
The safety snapshot reflects the studied record and its limitations.
Regulatory and identity status determine how the evidence should be interpreted.
Mechanisms
Human studies establish endocrine target engagement. A 12-month older-adult trial increased fat-free mass but did not improve strength or function, illustrating why biomarker and composition changes are not automatically clinical benefit.
A plausible mechanism can explain why a study was attempted. It does not prove that the compound improves a human outcome.
Studies
Study arms are reported for transparency. They describe what researchers did in a defined record and do not transfer across identities, routes, formulations, or populations.
A later trial phase can ask a more mature question, but it does not guarantee a positive result, regulatory approval, or relevance outside the studied population.
Randomized double-blind placebo-controlled trial
Healthy adults aged 60 to 81
Over one year, MK-677 increased GH/IGF-1 and fat-free mass but did not improve strength or physical function.
Study administration: Oral MK-677 versus placebo
Limitations: Selected older adults; not powered for uncommon or very long-term harms.
Randomized placebo-controlled trial
Older adults after hip fracture
In older adults after hip fracture, endocrine effects did not translate into the prespecified functional benefit.
Study administration: Not stated in the current record.
Limitations: Specific post-fracture population and mixed outcome record.
Randomized crossover physiology study
Healthy adults
Endpoints were not fully described in the current record.
Short human studies demonstrated endocrine target engagement and sleep-architecture effects.
Study administration: Not stated in the current record.
Limitations: Short physiological study; not a clinical sleep-outcome trial.
Safety snapshot
Human studies report appetite increase, edema, muscle pain, and worsened glucose measures in some settings; long-term cardiovascular and neoplastic safety are unresolved.
Controlled human evidenceReported events depend on population, formulation, route, exposure, comparator, and study size.
Open sourceThe current record does not support a reliable common-versus-uncommon frequency split.
Evidence boundaryUnder-detected or under-reported events must not be described as rare.
No source-qualified compound-specific warning or contraindication is encoded in the current record.
Evidence boundaryInvestigational; no FDA-approved ibutamoren product. Whether any population gains durable functional benefit that outweighs glucose, edema, appetite, cardiovascular, and other longer-term risks.
The current record does not identify a reliable compound-specific pattern of events that caused study discontinuation.
Evidence boundaryThis is an evidence gap, not proof that discontinuations did not occur.
No compound-specific patient-facing urgent-action threshold is established in the current Relay record.
Evidence boundaryRelay does not infer emergency guidance from study discontinuations, mechanism, or incomplete adverse-event reporting.
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PMID 18981485
PMID 21067829
PMID 9349662