This page shows what was measured, who it was measured in, and what that does not settle.
What Ibutamoren does in the body
Age-related muscle loss and fracture recovery — investigational, and the programme ended
Ghrelin is the hormone the stomach releases when it is empty; it makes you hungry and it tells the pituitary to release growth hormone. Ibutamoren copies ghrelin at its receptor, so it does both: appetite rises and growth hormone comes out in the pulsatile pattern of a young adult, which raises IGF-1 in the blood. That part is not in dispute and never has been. What Merck tested, repeatedly and expensively, was whether that translated into people being stronger, recovering better or thinking more clearly. In three different populations the answer was no.
What happened in people
Fat-free mass +1.1 kg against -0.5 kg on placebo over one year, confirmed by two-year exploratory analysis
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
Its recorded molecular formula is C27H36N4O5S, weighing 528.7.
PubChem record · 178024 · read 2026-08-29
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 125 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Fat-free mass and abdominal visceral fat after 1 year
Fat-free mass +1.1 kg (95% CI 0.7 to 1.5) versus -0.5 kg (-1.1 to 0.2), P < 0.001; no significant difference in abdominal visceral fat
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Fasting glucose +0.3 mmol/L (P = 0.015) with decreased insulin sensitivity; cortisol +47 nmol/L (P = 0.020); increased appetite, transient lower-extremity oedema and muscle pain. Increased fat-free mass did not produce any change in strength or function.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, capsule or liquid, 25 mg once daily in every published trial
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
Stair climbing power +12.5 W (95% CI -10.95 to 35.88, P = 0.292); gait speed 0.7-score difference (95% CI 0.17 to 1.28, P = 0.011); IGF-1 +51.4 ng/mL (P < 0.001); no improvement in several other functional measures
Repeated elsewhere
Failed to Replicate
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. The trial was terminated early because of a safety signal of congestive heart failure in a limited number of patients. The authors conclude the compound has an unfavourable safety profile in this population.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, capsule or liquid, 25 mg once daily in every published trial
Interval reported. 95% CI -10
Written into the record, not signed off as a reviewed claim.
Change from week 6 to week 26 in a panel of functional performance measures
✗ The study did not show it
Who was studied
Bach 2004 hip fracture trial across 13 centres
How many people
161
Study design
Randomised, double-blind, placebo-controlled, 6 months treatment plus 6 months follow-up
Compared against
A dummy treatment
Kind of result
What a body can do day to day
What was found
IGF-I rose 84% (95% CI 63 to 107) versus 17% (8 to 28) on placebo; no significant differences in functional performance measures or overall Sickness Impact Profile score
Repeated elsewhere
Replicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, capsule or liquid, 25 mg once daily in every published trial
Interval reported. 95% CI 63 to 107) versus 17% (8 to 28) on placebo; no significant differences in functional performance measures or overall Sickness Impact Profile score
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
□Living longer, or avoiding a major eventNo evidence recorded. Death, a heart attack, a stroke, a hospital stay.No registered study measures this.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
□Symptoms and quality of lifeNo evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
□A number that stands in for healthNo evidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.No registered study measures this.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
□AnimalsNo evidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.No animal record is stored.
■Cells in a dishEvidence recorded. Cells or chemistry on a bench, far from a whole body.Stored mechanism abstracts describe steps measured in cells or tissue.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Ibutamoren
What a person takes: Oral tablet, capsule or liquid, 25 mg once daily in every published trial.
The measurement behind this step
A once-daily oral dose. The unusual consistency of the clinical programme — 25 mg in all four major trials — means the human dose-response is narrow but the exposure is well characterised at that dose, over durations up to two years. That is far more human data than any SARM on this site has.
Getting in
Swallowed once daily at 25 mg
An oral tablet or capsule. Every published trial used the same dose, 25 mg once a day.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Orally active non-peptide spiroindane. Twenty-five milligrams once daily is the dose in Bach 2004, Nass 2008, Sevigny 2008 and Adunsky 2011 alike, which is unusual and makes the trials directly comparable.
It crosses into the brain regions that control growth hormone release and appetite.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Distributes to anterior pituitary somatotrophs and to the hypothalamic arcuate nucleus, the two sites where GHS-R1a expression is highest and where ghrelin itself acts.
It binds the receptor that the hunger hormone ghrelin normally uses, and switches it on.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Agonist at GHS-R1a, a Gq-coupled receptor. Activation raises intracellular calcium in somatotrophs and, in the arcuate nucleus, drives NPY and AgRP neurons — which is why appetite increase is the commonest adverse effect and was reported in the trials as subsiding over a few months.
The pituitary releases growth hormone in bursts, more of them and bigger, and the liver responds by making more IGF-1.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Enhanced pulsatile GH secretion rather than a continuous elevation, preserving the physiological pattern. Hepatic GH receptor signalling then raises circulating IGF-1 by 50% to 85% depending on the population, an effect that was measured and confirmed in every trial of the compound.
Fat-free mass rises; the clinical outcomes did not
Scales and scans show more lean tissue and more body weight. Strength tests, walking tests, recovery from fracture and cognitive scores did not move.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Fat-free mass +1.1 kg against -0.5 kg on placebo over one year, confirmed at two. No change in strength or function in the same trial; no significant functional benefit in the larger hip fracture trial; no effect on four Alzheimer disease scales in 563 patients. Fasting glucose rose and insulin sensitivity fell, the expected metabolic consequence of sustained growth hormone elevation.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
In trials: 65 healthy adults aged 60 to 81 over two years, 161 and then 123 patients recovering from hip fracture, 563 patients with mild to moderate Alzheimer disease, and postmenopausal women with osteoporosis. Outside trials: people wanting appetite, sleep and muscle gains, mostly alongside SARMs.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
Where the result stopped carrying
No effect on any of four clinical scales in 563 patients with Alzheimer disease despite unambiguous target engagement
No significant functional benefit in either hip fracture trial, and the second was terminated early for a congestive heart failure signal
No change in strength or function in the two-year healthy-ageing trial, which the authors state explicitly
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Still being tested
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablet, capsule or liquid, 25 mg once daily in every published trial
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
The identity record classes it as investigational; no register records an approval.
No source is stored against this line.
What is in the pack
A once-daily oral dose.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold. The rest of the recorded wording: The unusual consistency of the clinical programme — 25 mg in all four major trials — means the human dose-response is narrow but the exposure is well characterised at that dose, over durations up to two years. That is far more human data than any SARM on this site has.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Documented in trials: increased appetite subsiding over months, transient mild lower-extremity oedema, muscle pain, a small rise in fasting glucose with decreased insulin sensitivity, and a rise in cortisol. The hip fracture phase 2b was terminated early for a congestive heart failure signal and its authors describe the safety profile in that population as unfavourable. Fluid retention and insulin resistance are the expected consequences of sustained growth hormone elevation and are the reason growth hormone itself is not given to healthy people. One published case of hepatotoxicity resolving on withdrawal.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral tablet, capsule or liquid, 25 mg once daily in every published trial
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
A recorded note compares this form with the others that are sold. It is kept below, word for word.
§ A fixed RNAWiki sentence
Where this came from
Wording RNAWiki always uses, not a finding about this substance.
The recorded note, unchanged: The unusual consistency of the clinical programme — 25 mg in all four major trials — means the human dose-response is narrow but the exposure is well characterised at that dose, over durations up to two years. That is far more human data than any SARM on this site has.
No source is stored against this line.
What is recorded as being sold
6 products list this as an active ingredient in the United States drug directory. 6 of them contain it and nothing else.
FDA National Drug Code directory · 85207-063 · read 2026-08-29
They are sold as powder.
FDA National Drug Code directory · 85207-063 · read 2026-08-29
9 marketed supplement labels list this ingredient, classed as non-nutrient/non-botanical, other combinations and other.
Those labels carry all other, no claim and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine, investigational agent. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Ibutamoren studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That raising IGF-1 produces functional benefit — tested in three populations across 912 randomised participants and supported in none
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a 1.1 kg fat-free mass gain represents contractile tissue, when body cell mass was inferred from intracellular water and strength did not change
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the appetite and sleep effects reported by users are established outcomes; appetite increase is documented in the trials as an adverse effect that subsided, and sleep architecture was not a reported endpoint in any of them
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
How much did people take in the studies?
The sources RNAWiki checked hold nothing for this field.
Why it matters. A result belongs to an amount. Without the amount the result floats free.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
How fast does the body clear it?
The sources RNAWiki checked hold nothing for this field.
Why it matters. Without this, nothing on this page can say how long anything lasts.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Ibutamoren are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
Two years in 65 older adults: fat-free mass up 1.1 kg, strength unchanged
In plain words
In a two-year randomised trial, ibutamoren raised growth hormone and IGF-1 into the young-adult range and added 1.1 kg of fat-free mass while placebo lost 0.5 kg. It made no difference to strength or function.
What was measured
Fat-free mass and abdominal visceral fat at 1 year, confirmed at 2 years
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Nass et al. ran a two-year, double-blind, randomised, placebo-controlled, modified-crossover trial in 65 healthy adults aged 60 to 81, at 25 mg orally once daily. Growth hormone and IGF-1 rose into the healthy young-adult range. Fat-free mass changed by +1.1 kg (95% CI 0.7 to 1.5) on drug against -0.5 kg (-1.1 to 0.2) on placebo, P < 0.001; body cell mass by intracellular water followed the same pattern (P = 0.021). Body weight rose 2.7 kg against 0.8 kg (P = 0.003), with the average increase in limb fat greater on drug (1.1 kg versus 0.24 kg, P = 0.001) and no significant difference in abdominal visceral fat or total fat mass. The paper states plainly that the increased fat-free mass did not result in changes in strength or function, and that the two-year exploratory analyses confirmed the one-year results.
Written into the record, not signed off as a reviewed claim
Metabolic cost measured in the same trial: glucose up, insulin sensitivity down
In plain words
The same two-year trial recorded a rise in fasting blood sugar, a fall in insulin sensitivity and a rise in cortisol, alongside the muscle gain.
What was measured
Fasting glucose, insulin sensitivity, cortisol and lipid changes over 12 months
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In Nass et al., fasting blood glucose rose an average of 0.3 mmol/L (5 mg/dL) on MK-677 (P = 0.015) and insulin sensitivity decreased. Cortisol rose 47 nmol/L (95% CI 28 to 71), equivalent to 1.7 micrograms/dL (P = 0.020). LDL cholesterol fell 0.14 mmol/L relative to baseline (P = 0.026) with no between-group difference in total or HDL cholesterol. The commonest side effects were an increase in appetite that subsided over months, and transient mild lower-extremity oedema and muscle pain. These are the mechanistic consequences of chronic growth hormone elevation and they are reported in the same paper as the fat-free mass gain; secondary accounts of this compound often carry the first result and not the second.
Written into the record, not signed off as a reviewed claim
Alzheimer disease: IGF-1 up 73%, and no effect on any clinical scale
In plain words
In 563 patients with Alzheimer disease, a year of ibutamoren raised IGF-1 by nearly three quarters and changed nothing about the disease on any of the four measures used.
What was measured
CIBIC-plus, ADAS-Cog, ADCS-ADL and CDR-sob at 12 months
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Sevigny et al. randomised 563 patients with mild to moderate Alzheimer disease to MK-677 25 mg or placebo daily for 12 months, with 416 completing. Serum IGF-1 rose 60.1% at six weeks and 72.9% at twelve months. In mixed-effects models there were no significant differences between groups on the CIBIC-plus, or on mean change from baseline in ADAS-Cog, ADCS-ADL or CDR sum of boxes. The authors state the conclusion in the paper title: despite evidence of target engagement, the drug was ineffective. This is the textbook shape of a target-engagement-without-clinical-benefit result, and it is a stronger negative than a trial that simply failed to reach its dose.
Written into the record, not signed off as a reviewed claim
A hip fracture trial stopped early for congestive heart failure
In plain words
A 123-patient trial in people recovering from a hip fracture was terminated before it finished, because of a heart failure safety signal in a small number of patients.
What was measured
Functional performance measures and IGF-1 at 24 weeks; reason for early termination
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Adunsky et al. randomised 123 elderly hip fracture patients to MK-0677 25 mg daily or placebo. IGF-1 rose 51.4 ng/mL against placebo (95% CI 34.42 to 68.44, P < 0.001). Mean stair climbing power at 24 weeks rose 12.5 W against placebo but the confidence interval crossed zero (95% CI -10.95 to 35.88, P = 0.292); gait speed showed a 0.7-score difference in means (95% CI 0.17 to 1.28, P = 0.011); several other functional measures showed no improvement. The trial was terminated early due to a safety signal of congestive heart failure in a limited number of patients, and the authors conclude that MK-0677 has an unfavourable safety profile in this population. An earlier 161-patient trial by Bach et al. had already found an 84% IGF-1 rise with no significant difference from placebo in functional performance or in the overall Sickness Impact Profile score.
Written into the record, not signed off as a reviewed claim
IGF-1 is a target-engagement marker, not an outcome
In plain words
Every trial showed IGF-1 rising, which proves the drug reached its target. Not one trial showed that reaching the target helped anybody.
What was measured
That raising IGF-1 delivers the benefits attributed to growth hormone — the specific inference four randomised trials were built to test, and none supported
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
IGF-1 rose 84% in Bach et al., 51.4 ng/mL over placebo in Adunsky et al., 60.1% at six weeks and 72.9% at twelve months in Sevigny et al., and into the young-adult range in Nass et al. Across those four trials, spanning 912 randomised participants and three distinct populations, the clinical outcomes were: no change in strength or function in healthy older adults, no significant difference in functional performance after hip fracture in the larger of the two fracture trials, and no effect on any Alzheimer scale. A biomarker that moves in every trial while the outcome moves in none is the definition of an unvalidated surrogate, and the entire consumer case for this compound rests on that biomarker.
Written into the record, not signed off as a reviewed claim
Present as an undeclared drug in products, and hepatotoxicity reported
In plain words
Ibutamoren turned up inside products sold as SARMs that did not list it, and a case of liver injury in a man in his early thirties has been published.
What was measured
Frequency as an undeclared product ingredient; published hepatotoxicity case
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In Van Wagoner et al., 17 of 44 internet-purchased products (39%) contained an unapproved drug other than a SARM — ibutamoren, GW501516 or SR9009. Cobani et al. report transaminitis in an otherwise healthy man in his early thirties after two months of MK-677, resolving to normal after stopping. Reversible gynaecomastia and hypogonadism have been reported after commercial performance-enhancing supplement use involving this class. As with every case report on these pages, this establishes that the event occurs and gives no rate.
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What is not here
6 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A growth hormone secretagogue that reliably does exactly what it says — IGF-1 up by 51 to 84 percent, fat-free mass up 1.1 kg against a 0.5 kg loss on placebo — and produced no measurable gain in strength, function or cognition in any trial that looked for one, before a hip fracture trial was stopped early for heart failure.
Recorded evidence blocks (7)
Q1
What did Ibutamoren's largest trial (64 people) and its longest (3.7 years) measure?
64 people in Ibutamoren's largest registered study, 3.7 years in its longest registered window, measuring MK-0677 25 mg is superior to placebo in reducing symptoms of fibromyalgia, as assessed by the Fibromyalgia Impact Questionnaire (FIQ) over a 24-week treatment period. ClinicalTrials.gov · 2026-09-01
3 phase2, 1 na; NCT00395291; 2010-05; no ageing endpoint recorded. Last human test completed 2024, NCT05364684.
Interpretation These counts include studies where Ibutamoren was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
phase2
3
na
1
Last recorded human testNCT05364684
2024-12-23
recorded 2026-09-01 · last checked 2026-09-04
Q2
Ibutamoren was tested only in human — what did it show?
MK-0677 25 mg is superior to placebo in reducing symptoms of fibromyalgia, as assessed by the Fibromyalgia Impact Questionnaire (FIQ) over a 24-week treatment… — the recorded outcome words.
Show the evidence
humanNCT00116129
mechanism-only; MK-0677 25 mg is superior to placebo in reducing symptoms of fibromyalgia, as assessed by the Fibromyalgia Impact Questionnaire (FIQ) over a 24-week treatment period; 4
"Could not obtain drug supply from manufacturer"; 1 of 4 registered studies
Show the evidence
TrialNCT01343641
withdrawn; "Could not obtain drug supply from manufacturer"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Which one trial of Ibutamoren posted no result?
Posted no result
1 of 1 completed trials
Registrations
NCT00116129
Completion dates
oldest 2008-04
Show the evidence
TrialNCT00116129
2008-04
Q5
At the median, Ibutamoren's trials enrolled 30.5 people — anything larger?
Median enrolment
30.5
Largest enrolment
64
Registered trials counted
4
Q6
Was Ibutamoren studied with caloric restriction?
caloric restriction is named in Ibutamoren's label sentences: "During the first week of caloric restriction (i.e. diet alone), daily nitrogen losses were similar for both treatment groups (mean +/- SE; MK-677 group -2.67 +/- 0.40 g/day vs. placebo group -2.83 +/- 0.26 g/day)." openfda-label+europepmc · 1998-02-01
1 recorded statement; caloric restriction
Show the evidence
caloric restriction
During the first week of caloric restriction (i.e. diet alone), daily nitrogen losses were similar for both treatment groups (mean +/- SE; MK-677 group -2.67 +/- 0.40 g/day vs. placebo group -2.83 +/- 0.26 g/day).
"Despite evidence of target engagement as indicated by an increase in serum insulin-like growth factor-1, the human growth hormone secretagogue MK-677 25 mg was ineffective at slowing the rate of progression of Alzheimer disease."
recorded 2026-09-04 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ChEMBL 37 — CC BY-SA 3.0 Unported · ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · Open Targets 26.06 — CC0 · derived from this page's own recorded fields; no external licence · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 6 source rows
✓ no critical contamination: no quarantine open
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✓ no raw internal fields: enforced by the copy-contract test over the rendered page
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