MK-677: The Oral Growth Hormone Pill That Changed the Field
MK-0677 was characterized as the most potent orally active GH secretagogue with EC50 of 1.3 nM and confirmed anabolic effects in animals.
Quick Facts
What This Study Found
MK-0677 was characterized as the most potent orally active GH secretagogue, with EC50 of 1.3 nM in vitro, oral efficacy in dogs at 0.125 mg/kg, and confirmed anabolic effects in rodents.
Key Numbers
How They Did This
In vitro GH release from rat pituitary cells. Oral dosing studies in dogs measuring GH response. Repeated dosing for 4 days. Rodent anabolic efficacy studies with daily oral dosing.
Why This Research Matters
MK-0677 became the most widely studied and used oral GH secretagogue. This paper established its potency, oral bioavailability, and anabolic potential, which are the properties that made it a game-changer in the field.
The Bigger Picture
MK-677 became arguably the most important oral GH secretagogue ever developed. It opened the door to replacing GH injections with pills for certain conditions and became widely studied for age-related muscle loss, bone density, and sleep quality.
What This Study Doesn't Tell Us
Animal study (rat cells, dogs, rodents). Clinical trials later revealed more nuanced effects in humans including increased appetite, blood sugar changes, and water retention.
Questions This Raises
- ?How do the animal anabolic effects translate to human muscle and bone outcomes with long-term use?
- ?Can the appetite-stimulating and blood sugar effects be separated from the GH-releasing benefits?
Trust & Context
- Key Stat:
- EC50 = 1.3 nM MK-677 releases growth hormone at extremely low concentrations, making it the most potent oral GH secretagogue
- Evidence Grade:
- Strong — comprehensive characterization across in vitro, oral dog studies, and rodent anabolic models with dose-response data.
- Study Age:
- Published in 1995. This foundational paper launched decades of MK-677 research. Subsequent human clinical trials confirmed oral GH-releasing activity but revealed side effects including appetite stimulation and insulin resistance.
- Original Title:
- Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue.
- Published In:
- Proceedings of the National Academy of Sciences of the United States of America, 92(15), 7001-5 (1995)
- Authors:
- Patchett, A A(5), Nargund, R P(4), Tata, J R, Chen, M H, Barakat, K J, Johnston, D B, Cheng, K, Chan, W W, Butler, B, Hickey, G
- Database ID:
- RPEP-00339
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What is MK-677?
MK-677 (also called ibutamoren) is a small molecule that stimulates the body to release its own growth hormone when taken by mouth. It works by mimicking ghrelin at the growth hormone secretagogue receptor.
How is MK-677 different from growth hormone injections?
MK-677 stimulates your body's own GH release in a pulsatile pattern (more natural), can be taken as a pill, and is much less expensive. GH injections deliver a fixed dose of synthetic hormone directly.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-00339APA
Patchett, A A; Nargund, R P; Tata, J R; Chen, M H; Barakat, K J; Johnston, D B; Cheng, K; Chan, W W; Butler, B; Hickey, G. (1995). Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue.. Proceedings of the National Academy of Sciences of the United States of America, 92(15), 7001-5.
MLA
Patchett, A A, et al. "Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue.." Proceedings of the National Academy of Sciences of the United States of America, 1995.
RethinkPeptides
RethinkPeptides Research Database. "Design and biological activities of L-163,191 (MK-0677): a p..." RPEP-00339. Retrieved from https://rethinkpeptides.com/research/patchett-1995-design-and-biological-activities
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.