50 Best Peptides

This website is for informational purposes only and does not constitute medical advice. Read disclaimer

#48

MK-677

Growth HormoneIbutamorenIbutamoren MesylateNutrobalL-163,191

An orally active growth hormone secretagogue that mimics ghrelin to stimulate GH and IGF-1 release, notable for being a non-peptide small molecule rather than an injectable peptide.

Share:

Overview

MK-677 (Ibutamoren) is a non-peptide, orally active growth hormone secretagogue developed by Merck. Despite being frequently discussed alongside peptides, MK-677 is technically a small organic molecule that mimics the action of ghrelin by binding to and activating the GHS-R1a (ghrelin receptor) in the hypothalamus and pituitary gland. This stimulates the release of growth hormone in a pulsatile manner, and consequently increases IGF-1 levels.

The key advantage of MK-677 over peptide growth hormone secretagogues is its oral bioavailability — it can be taken as a pill rather than requiring injection. After oral administration, MK-677 produces a sustained increase in GH pulsatility and IGF-1 levels for up to 24 hours, allowing once-daily dosing. Studies have shown it can increase IGF-1 levels by 40-97% in various populations, maintaining these elevations with long-term treatment.

Clinical research on MK-677 has been relatively extensive compared to many research peptides. Studies in elderly populations showed improvements in body composition, bone mineral density, sleep quality, and nitrogen balance. A notable study in elderly subjects found that MK-677 restored the GH secretory pattern to that typical of young adults. Research in growth hormone-deficient adults showed comparable IGF-1 increases to injectable GH therapy at certain doses. Studies also demonstrated improved REM sleep and slow-wave sleep quality.

Despite positive clinical data, MK-677 has never received FDA approval. Concerns about sustained IGF-1 elevation, appetite stimulation (related to ghrelin-mimetic activity), potential insulin resistance with long-term use, and water retention have limited its commercial development. A large-scale study in elderly hip fracture patients (the MK-677 Study Group) showed no improvement in functional recovery despite increases in GH and IGF-1, raising questions about whether GH elevation alone is sufficient for therapeutic benefit in this population.

Research Uses & Applications

  • Oral stimulation of growth hormone and IGF-1 release
  • Research into age-related GH decline and body composition
  • Investigated for bone mineral density improvement in elderly populations
  • Studied for sleep quality improvement (slow-wave and REM sleep)
  • Research into muscle wasting and nitrogen balance improvement
  • Explored for GH deficiency as an oral alternative to injectable GH

Key Research Findings

  • Studies showed MK-677 increased IGF-1 levels by 40-97% in healthy elderly subjects with sustained elevation over 12 months.
  • Research demonstrated restoration of GH secretory patterns in elderly adults to profiles typical of young adults.
  • A 2-year study in elderly adults showed improvements in bone mineral density at the femoral neck and other sites.
  • Sleep studies documented increased slow-wave sleep duration and REM sleep quality with MK-677 treatment.
  • The hip fracture study showed no improvement in functional recovery despite significant increases in GH and IGF-1, questioning the clinical relevance of GH elevation alone.

Risks & Side Effects

  • Increased appetite and potential weight gain due to ghrelin receptor activation.
  • Water retention and edema, particularly in the first weeks of use.
  • Potential for insulin resistance and elevated fasting blood glucose with long-term use.
  • Theoretical cancer risk from sustained IGF-1 elevation.
  • Numbness and tingling in extremities (paresthesias) related to GH elevation.

Administration

Taken orally as a tablet or capsule, typically 10-25 mg once daily, usually at bedtime to minimize appetite side effects and align with natural GH release. No injection required. Some protocols start at lower doses (10 mg) and increase based on tolerance. Often used in cycles of 8-12 weeks, though longer use has been studied clinically.

Legal Status

MK-677 is not FDA-approved for any medical use. It is classified as a research chemical in most jurisdictions. Often marketed as a SARM (selective androgen receptor modulator) supplement, though this classification is incorrect as it acts on the ghrelin receptor, not androgen receptors. WADA lists it as a prohibited substance. The FDA has taken action against supplements containing MK-677.

Frequently Asked Questions

What is MK-677?

An orally active growth hormone secretagogue that mimics ghrelin to stimulate GH and IGF-1 release, notable for being a non-peptide small molecule rather than an injectable peptide.

What are the main uses of MK-677?

The primary research applications of MK-677 include: Oral stimulation of growth hormone and IGF-1 release; Research into age-related GH decline and body composition; Investigated for bone mineral density improvement in elderly populations; Studied for sleep quality improvement (slow-wave and REM sleep); Research into muscle wasting and nitrogen balance improvement; Explored for GH deficiency as an oral alternative to injectable GH.

What are the risks and side effects of MK-677?

Documented risks and side effects include: Increased appetite and potential weight gain due to ghrelin receptor activation.; Water retention and edema, particularly in the first weeks of use.; Potential for insulin resistance and elevated fasting blood glucose with long-term use.; Theoretical cancer risk from sustained IGF-1 elevation.; Numbness and tingling in extremities (paresthesias) related to GH elevation.. Always consult a healthcare professional before considering any peptide.

Is MK-677 legal?

MK-677 is not FDA-approved for any medical use. It is classified as a research chemical in most jurisdictions. Often marketed as a SARM (selective androgen receptor modulator) supplement, though this classification is incorrect as it acts on the ghrelin receptor, not androgen receptors. WADA lists it as a prohibited substance. The FDA has taken action against supplements containing MK-677.

How is MK-677 administered?

Taken orally as a tablet or capsule, typically 10-25 mg once daily, usually at bedtime to minimize appetite side effects and align with natural GH release. No injection required. Some protocols start at lower doses (10 mg) and increase based on tolerance. Often used in cycles of 8-12 weeks, though longer use has been studied clinically.

Related Peptides

#5

CJC-1295

Growth Hormone

#6

Ipamorelin

Growth Hormone

#11

Sermorelin

Growth Hormone

#12

Tesamorelin

Growth Hormone

Stay Updated on Peptide Research

Get the latest peptide research news and updates delivered to your inbox.

Official Store

Experience Peptides on Your Skin

Shop our curated collection of peptide-infused skincare — Copper Peptide serums, anti-aging treatments, hydrogel patches, and more.

Shop Peptide Skincare

Important Disclaimer

The information on this page is for educational and informational purposes only. It is not intended as medical advice. Always consult a qualified healthcare professional before considering any peptide or supplement. 50 Best Limited does not endorse, recommend, or promote the use of any peptide for self-administration. Read our full disclaimer.

← #47 ACE-031#49 PE-22-28 →