Emerging evidence · Grade B
Small molecule · not a peptide
MK-677
MK-677 (Ibutamoren)
Score
70 / 100
Half-life
~24 h (oral)
Class
Oral ghrelin mimetic
Status
Investigational
TL;DR
01
An orally active ghrelin mimetic (ibutamoren) — notably NOT a peptide but a small molecule — that raises growth hormone and IGF-1 with once-daily dosing.
02
It is the best-studied agent in this family: a 2-year RCT in older adults raised GH/IGF-1 to young-adult levels and increased lean (fat-free) mass.
03
But the same trial found no gain in strength or physical function from that added lean mass, and it worsened insulin sensitivity and raised blood glucose.
04
In a large trial it also failed to slow Alzheimer's disease despite clearly raising IGF-1 — a clean example of 'the biomarker moved, the outcome didn't.'
05
It reliably raises appetite and can cause fluid retention; it is not approved, is prohibited in sport, and its supply is unregulated.
GH / IGF-1
Raised to young-adult range
Annals 2008 · 1 yr
Fat-free mass
+1.1 kg
vs −0.5 placebo · 1 yr
Strength / function
No change
despite added lean mass
Insulin sensitivity
Decreased
fasting glucose ↑
Alzheimer's trial
Failed
no effect despite IGF-1 ↑73%
Part 01 · How it works
Mechanism.
MK-677 (ibutamoren) copies ghrelin's action at the pituitary but, unlike the injectable GHRPs, it's an orally active small molecule with a long enough duration for once-daily pills. It genuinely raises growth hormone and IGF-1 — that part is well proven in humans. The catch is what that does and doesn't translate into: it adds lean body mass but, in the key trial, that extra mass came with no improvement in strength or function, while it also pushed blood sugar up and insulin sensitivity down. It's a clear case of a drug hitting its biological target without delivering the outcome people want.
It reliably turns the growth-hormone dial up with a daily pill — but turning that dial added weight without added strength, and nudged blood sugar the wrong way. The gauge moved; the payoff didn't.
Oral ghrelin mimetic
Non-peptide small molecule agonist at the GH-secretagogue receptor; orally bioavailable, ~24-h action.
GH/IGF-1 elevation
Raises pulsatile GH and IGF-1 to young-adult levels in older adults (proven in RCTs).
Body composition
Increases fat-free mass and body weight; visceral fat unchanged; no strength/function gain.
Metabolic effect
Decreases insulin sensitivity and raises fasting glucose; increases appetite and cortisol.
Part 02 · Dosing & administration
How it's taken.
Clinical · trial-validatedValues below describe how MK-677 has been administered in human clinical trials and/or approved labeling. Provided for educational purposes only — this is not medical advice and not instructions for self-administration. Consult your healthcare provider before making any health decision.
Standard dose
10–25 mg once daily (25 mg is the pivotal-trial dose)
Oral · Once daily, often taken at bedtime
Duration
Investigational; clinical studies ranged from days to 2 years. No established or approved duration of use.
·
The 25 mg once-daily dose comes directly from human RCTs (Nass 2008, a 2-year double-blind trial) — hence a clinical dose basis.
·
Not FDA-approved and sold only as an unregulated research chemical of uncertain purity — "clinical dose basis" describes the number’s origin, not product legitimacy.
·
Raises fasting glucose and lowers insulin sensitivity (documented in the RCT); baseline + follow-up labs and clinician oversight are warranted.
Need help with reconstitution?
Use the free peptide calculator for dilution, unit conversion, and injection volume.
Part 03 · Safety
Side effects, rare serious events, who shouldn't.
Common
Increased appetite
Often subsides after a few months (Annals RCT).
Common
Lower-extremity edema
Transient fluid retention, a GH-axis effect.
Common
Muscle pain
Reported in the long-term trial.
Common
Fatigue / lethargy
Anecdotal and in some trial reports.
Reported
Serious · rare
Decreased insulin sensitivity / hyperglycemia
Fasting glucose rose and insulin sensitivity fell in the 2-year RCT — relevant to diabetes/pre-diabetes.
Documented
Increased cortisol
Small rise observed in the long-term trial.
Modest
IGF-1 elevation / mitogenic caution
Sustained IGF-1 elevation carries a theoretical mitogenic concern.
Expected
Product-quality risk
Sold as a research chemical; purity/dose not guaranteed.
Source-dependent
Absolute · do not use
×
Pregnancy, attempting conception, or breastfeeding (no safety data; raises IGF-1)
×
Diabetes, prediabetes, or significant insulin resistance, given reduced insulin sensitivity and higher fasting glucose
×
Heart failure or significant cardiac disease, given fluid retention and an observed congestive-heart-failure safety signal
×
Active or history of cancer, or high cancer risk, because of theoretical concern with elevating IGF-1 (a growth-promoting factor)
×
Active acromegaly or known GH/IGF-1 excess
×
Severe fluid-retention states or uncontrolled hypertension
Relative · discuss first
!
Diabetes or impaired glucose tolerance — worsens insulin sensitivity
!
Active or prior malignancy — IGF-1 mitogenic caution
!
Heart failure or fluid-overload states — edema risk
!
Competitive athletes — prohibited in sport
!
Pregnancy or breastfeeding — no data
Interactions
Insulin and insulin secretagogues (e.g., sulfonylureas)
MK-677 reduces insulin sensitivity and raises fasting glucose, which may worsen glycemic control and complicate dosing of glucose-lowering therapy
Major
Other glucose-lowering medications (e.g., metformin, GLP-1 receptor agonists)
May counteract glycemic goals; closer glucose monitoring is warranted if combined
Moderate
Corticosteroids
Additive effects on blood glucose and fluid retention; MK-677 itself modestly raises cortisol
Moderate
Injectable growth hormone or other GH secretagogues
Stacking can cause excessive GH/IGF-1 elevation, fluid retention, joint pain, and metabolic strain
Major
Drugs that prolong the QT interval
Limited data suggested a possible small increase in QT in early studies; caution with other QT-prolonging agents
Moderate
CYP3A4 inhibitors or inducers
MK-677 is metabolized hepatically, so strong CYP3A4 modulators could theoretically alter its exposure
Minor
Labs to monitor
Fasting glucose
Baseline and every 1-3 months
MK-677 raised fasting glucose and reduced insulin sensitivity in trials; rising levels may signal worsening glucose control
HbA1c
Baseline and every 3 months
Tracks longer-term blood sugar, which is the key metabolic risk given reduced insulin sensitivity
IGF-1
Baseline and every 3 months
Primary biomarker of the GH axis response; helps gauge target engagement and avoid excessive elevation
Comprehensive metabolic panel (including fasting insulin)
Baseline and periodically
Monitors glucose, electrolytes, and fluid/renal status given appetite, weight gain, and fluid-retention effects
Body weight and signs of edema or breathlessness
Ongoing self-monitoring; clinical review as needed
Fluid retention and a congestive-heart-failure safety signal were observed; rapid weight gain, swelling, or shortness of breath warrants prompt evaluation
Part 04 · Evidence
How strong is the evidence?
70
Grade B
Grade B, Emerging — and the best-evidenced of the secretagogues, which cuts both ways. Real RCTs confirm it raises GH/IGF-1 and lean mass, but those same trials show no functional benefit, worsened glucose handling, and a failed Alzheimer's outcome. Strong target engagement, weak proven payoff.
Mechanistic plausibility
Oral ghrelin mimetic with clearly demonstrated GH/IGF-1 elevation.
82
Human evidence
Multiple RCTs including a 2-year body-composition trial and a large Alzheimer's trial — unusually strong for this family.
72
Safety & tolerability
Appetite increase, edema, muscle pain, and importantly reduced insulin sensitivity / higher glucose; cortisol rise.
60
Outcome benefit
Added lean mass but no strength/function gain; failed to alter Alzheimer's progression.
48
Independence
NIH- and industry-funded RCTs across independent centers.
70
Part 05 · Research log
Every study we cite.
We list each study with its methodology, funding source, and our quality grade. Flagged studies aren't dismissed — they're tagged so you can weigh them.
01
2008
Annals of Internal Medicine Flagged
Oral ghrelin mimetic (MK-677) on body composition in healthy older adults
MK-677 25 mg raised GH/IGF-1 to young-adult levels and increased fat-free mass (+1.1 vs −0.5 kg) and body weight, but raised fasting glucose and decreased insulin sensitivity, and the added lean mass produced no change in strength or function.
2-year, double-blind, randomized, placebo-controlled · n = 65 · Well-controlled; the key nuance is the dissociation of lean-mass gain from functional benefit.
PMID 18981485 ↗
High
02
2008
Neurology Industry funded
MK-677 in mild-to-moderate Alzheimer's disease — phase 3
Raised serum IGF-1 by ~73% (clear target engagement) but produced no benefit on any cognitive or functional Alzheimer's endpoint versus placebo.
12-month, double-blind, multicenter RCT · n = 563 · Large, well-powered negative trial; strong evidence that raising IGF-1 did not help this outcome.
PMID 19015485 ↗
High
Evidence against
What didn't work, and where the evidence is thin.
Every publication is incentivized to tell you a peptide works. We catalogue the null results, failed trials, and mechanism limits we found in the same literature — so you can weigh them against the upside, with your provider.
01
Adds lean mass but not strength or function — and worsens glucose
Null result Annals of Internal Medicine · 2008
Over a year, MK-677 raised GH/IGF-1 and fat-free mass but produced no improvement in strength or physical function, while raising fasting glucose and decreasing insulin sensitivity.
What this means: The headline 'builds lean mass' is real but hollow if it doesn't improve strength or function — and it comes with a metabolic cost that matters for anyone glucose-sensitive.
PMID 18981485 ↗
02
Failed its Alzheimer's trial despite clear target engagement
Failed trial Neurology · 2008
In 563 patients, MK-677 raised IGF-1 by ~73% but had no effect on cognition or function in Alzheimer's disease.
What this means: A textbook 'biomarker moved, outcome didn't' result — a caution against assuming that raising GH/IGF-1 delivers clinical benefit.
PMID 19015485 ↗
Part 06 · Cost & access
Where it's available, at what price.
United States
Not approved
Never approved (Merck discontinued development). Sold as a research chemical; prohibited in sport. No legal consumer medicine.
Grey-market; unregulated
European Union
Not approved
No approved product; prohibited in sport.
N/A
United Kingdom
Not approved
No approved product; prohibited in sport.
N/A
Canada
Not approved
No approved product; prohibited in sport.
N/A
The Peptide Column takes no affiliate commission from any source. MK-677 (ibutamoren) is not an approved medicine, is prohibited in sport, and is sold as an unregulated research chemical; its lean-mass effect did not translate into strength or function in trials. We link only to clinician-directed care, never to sellers.
Part 07 · Your appointment
Questions to bring.
01
Given that MK-677 is not FDA-approved and is sold only as a research chemical, is there any role for it in my situation, and what are the safety and sourcing risks?
02
I have (or am at risk for) prediabetes, diabetes, or heart failure. How would raising my IGF-1 and lowering my insulin sensitivity affect those conditions?
03
What baseline and follow-up labs, including fasting glucose, HbA1c, and IGF-1, should I have if I were to consider this, and how often?
04
Are there FDA-approved alternatives that address my actual goal (for example, evaluating and treating a documented growth-hormone deficiency) with a known safety profile?
References
Every citation, numbered.
Citation list. For our editorial read of each study — including bias flags and quality grades — see the Research log above.
- 01. Oral ghrelin mimetic (MK-677) on body composition in healthy older adults · Annals of Internal Medicine, 2008 · PMID 18981485 ↗
- 02.
- 03. ClinicalTrials.gov / literature. MK-677 body-composition and Alzheimer's RCTs
- 04.