MK-677 (Ibutamoren) Tablets

Investigational Oral Growth Hormone Secretagogue (Ghrelin Receptor Agonist)

Last Updated: June 27, 2026
Medical Review Status: Reviewed for scientific accuracy
Reviewed By: Pharmaceutical Affairs Team
Reading Time: 6 min read

Quick Facts

Quick Answer

MK-677, also known as Ibutamoren, is an investigational oral growth hormone secretagogue that stimulates the ghrelin receptor (GHSR-1a), promoting the natural release of growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Unlike recombinant growth hormone, MK-677 is taken orally and works by enhancing endogenous hormone secretion. It remains an investigational compound and has not been approved by the U.S. FDA, UK MHRA, or EMA for the treatment of any medical condition.

Why is MK-677 Different?

• Orally active growth hormone secretagogue
• Stimulates natural GH and IGF-1 production
• Long elimination half-life allowing once-daily administration in research settings
• Does not directly administer growth hormone
• Studied for muscle mass, bone density, sleep quality, and age-related decline
• Investigational status with ongoing scientific interest

Product Overview

MK-677 (Ibutamoren) Tablets contain Ibutamoren Mesylate, an orally active, non-peptide growth hormone secretagogue investigated for its ability to increase endogenous growth hormone and insulin-like growth factor-1 (IGF-1) levels through activation of the ghrelin receptor. Unlike injectable recombinant growth hormone therapies, MK-677 is designed to stimulate the body’s natural hormonal pathways and has been evaluated in multiple clinical and preclinical studies exploring endocrine function, body composition, skeletal health, metabolism, and healthy aging.

Researchers have investigated MK-677 across several therapeutic areas, including adult growth hormone deficiency, sarcopenia, frailty associated with aging, osteoporosis, muscle wasting disorders, recovery from catabolic illness, and sleep physiology. Studies have demonstrated sustained increases in circulating GH and IGF-1 concentrations, although clinical outcomes have varied depending on patient population, study duration, and endpoints.

Because MK-677 remains an investigational compound, it has not received approval from major regulatory authorities for the treatment or prevention of any disease. Its use is currently limited to scientific research and clinical investigation where permitted under applicable regulations.

This information is intended to provide an evidence-based overview of MK-677 (Ibutamoren) and should not be interpreted as medical advice, treatment guidance, or an endorsement of unapproved therapeutic use.

Product Information

Mechanism of Action

MK-677 selectively activates the ghrelin receptor (growth hormone secretagogue receptor, GHSR-1a), stimulating pulsatile secretion of endogenous growth hormone from the anterior pituitary. Elevated growth hormone subsequently increases hepatic production of insulin-like growth factor-1 (IGF-1), a hormone involved in tissue growth, muscle metabolism, bone remodeling, and cellular repair. Unlike exogenous growth hormone administration, MK-677 enhances physiological hormone release through endogenous endocrine pathways.

Research Areas

• Adult Growth Hormone Deficiency
• Sarcopenia
• Age-Related Muscle Loss
• Cachexia and Muscle Wasting
• Bone Mineral Density Research
• Sleep Physiology
• Metabolic Function
• Healthy Aging
• Endocrinology Research

Potential Research Findings

• Increased circulating growth hormone levels
• Increased IGF-1 concentrations
• Improved lean body mass in selected studies
• Potential effects on bone metabolism
• Improved slow-wave sleep observed in certain clinical investigations
• Long-term clinical benefit remains under investigation

Safety Considerations

Clinical studies have reported adverse events including increased appetite, transient edema, muscle discomfort, fatigue, elevated fasting glucose, insulin resistance, and weight gain in some participants. The long-term safety profile has not been fully established, and the benefit-risk profile continues to be evaluated in clinical research.

Frequently Asked Questions

What is MK-677 (Ibutamoren)?

MK-677 is an investigational oral growth hormone secretagogue that activates the ghrelin receptor to stimulate natural growth hormone and IGF-1 secretion.

Is MK-677 approved by the FDA?

No. MK-677 has not been approved by the U.S. Food and Drug Administration, the UK Medicines and Healthcare products Regulatory Agency, or the European Medicines Agency for the treatment of any disease.

Is MK-677 a steroid?

No. MK-677 is not an anabolic steroid. It is a ghrelin receptor agonist that stimulates endogenous growth hormone secretion.

Is MK-677 the same as growth hormone?

No. MK-677 does not contain growth hormone. Instead, it promotes the body’s natural release of growth hormone through activation of the ghrelin receptor.

What conditions has MK-677 been studied for?

Clinical research has investigated MK-677 in growth hormone deficiency, sarcopenia, muscle wasting, osteoporosis, metabolic disorders, and healthy aging, although it remains investigational.

References

1. Peer-reviewed clinical studies evaluating MK-677 (Ibutamoren).
2. National Institutes of Health (NIH) publications.
3. ClinicalTrials.gov investigational studies.
4. Endocrinology and metabolism research literature.
5. Published pharmacology and safety reviews.

Medical Disclaimer

This information is provided solely for educational and scientific purposes. MK-677 (Ibutamoren) is an investigational compound and has not been approved by the FDA, MHRA, EMA, or other major regulatory authorities for the treatment or prevention of any disease. The content presented here should not be interpreted as medical advice, prescribing guidance, or a recommendation for therapeutic use. Any investigational use should be conducted in accordance with applicable laws, ethical standards, and institutional research protocols.