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Investigational oral growth-hormone secretagogue · no approved dose
MK-677 (ibutamoren)
MK-677 increased fat-free mass in one trial but did not improve strength or function. A separate trial stopped after a heart-failure signal.
- More fat-free mass did not mean better strength or function.
- A separate trial after hip fracture stopped after a heart-failure signal.
- These studies do not establish an approved dose.
Ibutamoren mesylate is studied as MK-677, MK-0677, MK0677, and LUM-201. It is an oral growth-hormone secretagogue. It prompts the body to raise its own growth hormone and IGF-1.
It is not recombinant human growth hormone. It is not a SARM.
One randomized trial enrolled healthy adults age 60–81. The active group took 25 mg once daily for one year. Mean fat-free mass rose by 1.1 kg with MK-677.
It changed by −0.5 kg with placebo. The added mass did not improve measured strength or function. Fasting glucose rose and insulin sensitivity fell.
Mild, short-term swelling of the lower limbs was reported. A separate trial enrolled people after hip fracture. There, 25 mg/day did not improve most measures of function.
The trial stopped early after a congestive-heart-failure signal. These are research findings, not an approved dose. They do not show an anti-aging result or set a personal schedule.
What matters first
- Body composition is not function: The longer trial enrolled healthy older adults. Their fat-free mass rose. Measured strength and function did not improve.
- Keep the serious safety signal visible: The later hip-fracture trial stopped early. FDA’s review reports congestive heart failure in 4/62 active and 1/61 placebo people.
- Keep glucose and fluid findings visible: The reviewed trials report higher fasting glucose and lower insulin sensitivity. They also report swelling or fluid overload and weight gain. These findings belong with the groups in which they occurred.
- Study counts conflict: The stopped hip-fracture registry lists 83 enrolled. The paper and FDA review report 123 randomized. The healthy-adult paper reports 71 randomized. Its registry lists 72, with no planned-or-actual label.
- Names do not transfer approval: LUM-201 is another research name for ibutamoren. An approved growth-hormone injection is a different product. Its approval, use, and dose do not extend to ibutamoren.
- Every amount is research exposure: Each oral schedule belongs to its studied group, duration, and endpoints. None creates a consumer dose-escalation plan.
Healthy older-adult evidence
The one-year body-composition trial
The full paper reports 71 healthy volunteers age 60–81. They were randomized to MK-677 25 mg once daily or placebo. The two-year trial used a double-blind, modified-crossover design.
Sixty-five people completed the key first year. The separate NCT00474279 registry lists enrollment of 72. It does not say planned or actual.
It posts no results. The one-person difference remains unresolved.
The supervised protocol allowed a blinded dose cut from 25 to 10 mg daily. Four people had that cut. Two had higher fasting glucose.
One was after the year-two crossover. The other person withdrew after three months. Two more had increased joint pain.
Both withdrew after 12 months. This detail matters for safety. It is not a consumer dose-adjustment instruction.
At one year:
| Measure | MK-677 25 mg once daily | Placebo | Meaning |
|---|---|---|---|
| Mean fat-free-mass change | +1.1 kg | −0.5 kg | Body-composition endpoint; it did not produce improved measured strength or function |
| Average change in body weight | +2.7 kg | +0.8 kg | Weight increased rather than establishing selective muscle gain |
| Mean fasting-glucose change | +0.3 mmol/L (+5 mg/dL) | Not supplied as a matching value in the abstract | Glucose rose and insulin sensitivity decreased with MK-677 |
The PubMed abstract lists three frequent effects. Appetite rose, then eased after several months. Mild swelling in the lower limbs was short-lived.
Muscle pain was also reported. People were generally healthy. Those with diabetes were excluded.
Almost all were White. The authors say the trial was too small and too short to assess endpoints for function. It does not establish treatment for frailty, sarcopenia, disability, or aging.
Short hormone and bone-marker studies
The first dose-response trial enrolled 32 healthy adults age 64–81. They received placebo or 2, 10, or 25 mg MK-677 once daily. There were separate 14- and 28-day periods.
Growth hormone rose with dose. At 25 mg/day, mean IGF-1 started at 141 micrograms/L. It reached 219 at two weeks and 265 at four weeks.
Mean fasting glucose rose from 5.4 to 6.8 mmol/L at four weeks. This short study measured hormones and lab values. It did not measure strength or mobility.
It did not measure a clinical anti-aging outcome.
Three bone-marker trials included 187 adults age 65 or older. Healthy groups received 10 or 25 mg daily for two weeks. Another schedule gave 25 mg for two weeks, then 50 mg for two weeks.
A group with impaired function took a different schedule. It gave 5, 10, or 25 mg daily for two weeks. This was followed by 25 mg daily for seven weeks.
IGF-1 rose. Lab markers of bone formation and breakdown also rose. These changes do not show stronger bones.
They do not show that fractures or impaired function were prevented.
Hip-fracture trials
Earlier six-month study
The earlier randomized hip-fracture paper enrolled 161 adults age 65 or older. All had been mobile before their hip fracture. They joined shortly after surgery.
FDA’s study review reports the assigned groups. There were 84 on MK-0677 25 mg once daily and 77 on placebo. Treatment lasted six months, followed by six months without it.
The protocol excluded diabetes, uncontrolled high blood pressure, and congestive heart failure.
IGF-1 rose 84% with MK-0677 and 17% with placebo. No overall measure of function differed significantly. Nor did the overall nursing-home sickness-impact score.
Some figures showed trends. These did not prove a statistically significant benefit in function. The authors said meaningful effects on physical function remained uncertain.
Later Phase 2b study stopped for safety
The later Phase 2b paper reports 123 older people after hip fracture. They were randomized for 24 weeks. MK-0677 was 25 mg/day (n=62).
Placebo had n=61. Mean stair-climbing power did not improve significantly versus placebo. The difference was 12.5 W; 95% CI −10.95 to 35.88; p=0.292.
One reported gait-speed score improved. Its difference was 0.7; 95% CI 0.17–1.28; p=0.011. Several other measures of function did not improve.
IGF-1 rose, but most measures of function did not improve.
The trial stopped early after a congestive-heart-failure signal. FDA’s 2024 evaluation reports heart failure in 4/62 MK-0677 and 1/61 placebo people. Raised blood glucose occurred in 4/62 versus 1/61.
Raised HbA1c occurred in 3/62 versus none. The active group gained more weight. Both systolic and diastolic blood pressure stayed higher.
The paper calls the safety profile unfavorable in this group.
The NCT00128115 registry is TERMINATED. It lists actual enrollment of 83 and posts no results. The paper and FDA review report 123 randomized.
This review cannot resolve that difference. Both counts must stay labeled by source.
The heart-failure finding was 4/62 versus 1/61. This is a serious signal from a small group of older people after fracture. It is not a rate for all users.
It caused the trial’s early stop. It must stay beside each summary of benefits or studied doses.
Current study and US regulatory status
The current ClinicalTrials.gov ibutamoren query returns eight records. Five are completed. One was withdrawn with zero enrollment.
One was terminated, and one is recruiting. The recruiting record is a Phase 3 study in children with growth-hormone deficiency. It uses the LUM-201 name.
It does not supply adult sarcopenia, anti-aging, or post-fracture evidence. But the research program cannot be called abandoned worldwide.
FDA describes Drugs@FDA as its approved-product database. We checked its September 4, 2026 data page and 12-table archive. No match appeared, regardless of letter case, for ibutamoren, MK-677, MK-0677, MK0677, LUM-201, or L-163,191.
The archive does contain somatropin records. Those confirm that the search can find entries. They refer to different injected drugs.
The exact openFDA ingredient query returned HTTP 404 “No matches found.”
The exact DailyMed search found two historical ibutamoren-mesylate powder SPL records. They are dated 2016 and 2017. The result was not zero.
But those records do not prove FDA approval. No ibutamoren product was found in the current US approval sources checked. Another growth-hormone drug cannot lend it an approval or dose.
That includes somatropin.
FDA’s 2024 review says ibutamoren mesylate is not in an FDA-approved drug. It proposed against adding it to the 503A bulk-drug-substances list. The review found too little evidence of meaningful clinical benefit.
It also raised safety concerns. These include high blood glucose and raised liver enzymes. They include swelling, fluid overload, and congestive heart failure.
This was an agency review for an advisory-committee proceeding. It is not presented as a later final rule.
Reader questions
Is MK-677 the same as ibutamoren?
FDA uses several names for this same substance. They are ibutamoren mesylate, MK-677, MK-0677, MK0677, and LUM-201. Each study keeps the name it used.
This helps avoid pooling records by mistake.
Is ibutamoren growth hormone or a SARM?
No. It is an oral growth-hormone secretagogue. It prompts the body to raise its own growth hormone and IGF-1.
It is not recombinant human growth hormone. It is not a SARM.
Did MK-677 build muscle in healthy older adults?
The one-year trial found a mean fat-free-mass gain of 1.1 kg with MK-677. Placebo showed a 0.5 kg loss. Fat-free mass describes body composition.
The gain did not improve measured strength or function. The study did not establish treatment for sarcopenia. It did not establish an anti-aging benefit.
What doses were studied?
The reviewed studies used different oral schedules. A short dose-response trial used 2, 10, or 25 mg daily. The longer healthy-adult and hip-fracture trials used 25 mg daily.
Short bone-marker trials included 5, 10, 25, and 50 mg phases. These are research schedules. They do not set a default dose or dose-escalation plan.
What happened in the stopped hip-fracture trial?
Most measures of function did not improve. The trial stopped early after a congestive-heart-failure signal. FDA reports heart failure in 4/62 active and 1/61 placebo people.
There were also glucose, weight, and blood-pressure concerns. The signal belongs to this studied group. It must not be hidden or called a rate for all users.
Is ibutamoren approved in the United States?
Current Drugs@FDA and exact openFDA ingredient searches found no approved ibutamoren product. DailyMed contained two historical powder records. A DailyMed entry does not prove approval.
Somatropin’s approval, approved uses, and dose do not apply to MK-677.
Can these study amounts be used as a personal schedule?
No. These amounts describe controlled research in selected people. They are not a clinical recommendation or wellness schedule.
They do not establish anti-aging use. They do not set a schedule for use without supervision.