What it is
MK-677 (ibutamoren) is a non-peptide, orally active growth hormone secretagogue. It is the one compound in the Pantheon catalogue taken as a capsule rather than an injection, and one of the few with year-long human trial data behind it.
Mechanism of action
MK-677 binds the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus, which raises pulsatile growth hormone release and, downstream, circulating IGF-1. Because it is taken by mouth and acts for most of a day, one daily capsule holds GH and IGF-1 in the upper part of the normal range.
Evidence summary
In healthy older adults, a year of daily MK-677 raised GH and IGF-1 to young-adult levels and added about 1.1 kg of fat-free mass, with no strength gain and no change in visceral fat (Nass 2008). Shorter human studies showed improved sleep depth (Copinschi 1997), reversal of diet-induced muscle breakdown (Murphy 1998), higher bone-turnover markers (Murphy 2001) and a rise in GH secretion in obese adults (Svensson 1998). The trade-offs in the same trials were a larger appetite, some water retention and a small rise in fasting glucose.
Pantheon dosing guide
- Application
- Oral.
- BAC Water
- NA
- Dose
- 1 to 2 capsules.
- Frequency & Cycle Length
- Daily. 5 weeks to 10 weeks depending on dosing.
- Timing
- Take on an empty stomach.
- Key Benefits
- Stimulates natural growth hormone and IGF-1 release. Promotes muscle growth and strength. Boosts bone density and joint health. Improves recovery. Improves sleep quality.
Side effects & safety
- A bigger appetite and some water retention are the effects people notice first
- Numbness or tingling is occasionally reported; in the year-long human trial the recorded effects were mild swelling in the lower legs and muscle aches, not nerve symptoms (Nass 2008)
- Fasting glucose rose slightly and insulin sensitivity fell over a year of daily use, so run it with a stopping point in view and check glucose on longer runs
- Long-term safety beyond one year has not been studied
Cited studies
- Nass R, Pezzoli SS, Oliveri MC, et al. (2008). Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Annals of Internal Medicine.PMID 18981485Read source ↗
- Copinschi G, Leproult R, Van Onderbergen A, et al. (1997). Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man. Neuroendocrinology.PMID 9349662Read source ↗
- Murphy MG, Plunkett LM, Gertz BJ, et al. (1998). MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. Journal of Clinical Endocrinology & Metabolism.PMID 9467534Read source ↗
- Murphy MG, Weiss S, McClung M, et al. (2001). Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women. Journal of Clinical Endocrinology & Metabolism.PMID 11238495Read source ↗
- Svensson J, Lönn L, Jansson JO, et al. (1998). Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. Journal of Clinical Endocrinology & Metabolism.PMID 9467542Read source ↗
- Chapman IM, Bach MA, Van Cauter E, et al. (1996). Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects. Journal of Clinical Endocrinology & Metabolism.PMID 8954023Read source ↗
All content is for research and educational purposes. Peptides described are sold for laboratory research use only and are not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before beginning any protocol.