Ibutamoren, Nutrobal
Evidence Grade C — Moderate human evidence. 37 published studies, 28 human. 8 registered clinical trials.
MK-677 (ibutamoren) is an orally active small molecule — not a peptide — that stimulates growth hormone release by activating the ghrelin receptor. Developed by Merck, it was never approved after clinical trials showed that the growth hormone and IGF-1 increases it produced did not translate into meaningful functional improvements. It is widely available through unregulated sources.
37 published studies: 28 human, 6 animal, 5 in-vitro, 3 reviews
MK-677 has no marketing authorisation from any regulatory agency. Multiple clinical trials were conducted by Merck: a 2-year study in elderly subjects showed increased IGF-1 and modest body composition changes but no functional improvement. A Phase II trial in hip fracture recovery did not meet its primary endpoints. Clinical development was discontinued.
MK-677 is not a peptide but a small-molecule peptidomimetic. Despite generating pharmacological effects on growth hormone and IGF-1 levels, these effects did not translate into clinically meaningful outcomes in the trials conducted. Products available through unregulated channels lack pharmaceutical quality assurance.
Research suggests MK-677 activates the ghrelin receptor orally, producing sustained growth hormone elevation and IGF-1 increases over 24 hours. It also stimulates appetite (consistent with ghrelin receptor activation). Unlike injectable growth hormone secretagogue peptides, its oral bioavailability allows sustained daily dosing without injection. These pharmacological observations are from clinical studies that did not demonstrate functional clinical benefit.
Research suggests a two-year study in elderly subjects showed increased IGF-1 levels and modest body composition changes but no functional improvement — the growth hormone elevation did not make people stronger or more mobile. A Phase II hip fracture recovery trial also failed to meet its primary endpoints. Clinical development was discontinued. Side effects include appetite and weight gain, increased fasting glucose (HbA1c rose from 5.5% to 5.8% over two years), and oedema. The unknown long-term cancer risk of sustained IGF-1 elevation is a theoretical concern. It is prohibited by WADA. Products from unregulated channels lack pharmaceutical quality assurance.
Phase 3 Study of LUM-201 in Children With Growth Hormone Deficiency
The Impact of Ibutamoren on Nonalcoholic Fatty Liver Disease
Growth Hormone Secretagogue MK-0677's Effect on Lean Body Mass in Chronic Kidney Disease Stage 4/5 Subjects
Growth Hormone Secretagogue MK-0677 Effect on IGF-1 Levels in ESRD Patients
Treatment of Sarcopenia in Post-Hip Fracture Patients (0677-032)
The information on this page is provided for educational and research reference purposes only. This is not medical advice. Always consult a qualified healthcare professional before making any health-related decisions.
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