Research Overview

MK-677 (Ibutamoren) is an orally active, non-peptidic mimetic of the natural GH secretagogue ghrelin, binding selectively to GHS-R1a in the pituitary and hypothalamus [1,2]. It is by far the most extensively characterized molecule in its class. In a landmark two-year placebo-controlled trial in healthy elderly adults, daily oral 25 mg restored serum IGF-1 to the levels of healthy young adults, increased lean body mass by 1.1 kg, preserved bone mineral density, and improved deep slow-wave sleep duration — all while preserving the physiological pulsatile architecture of GH secretion that is disrupted by recombinant GH injection [2]. MK-677 has also been investigated in fall-prone elderly patients post-hip-fracture (functional outcome benefits, reduced fall recurrence), in obese subjects (favorable changes in fat-free mass), and in pediatric GHD where it produced linear growth-velocity acceleration [1–3]. Across thousands of patient-years, the molecule has exhibited a benign tolerability profile, with mild fluid retention and transient appetite stimulation as the principal observations.

Primary Research Areas

• GH / IGF-1 axis pharmacology: the gold-standard probe for studying physiological pulsatile growth hormone release driven by ghrelin-receptor agonism, distinguished from suprapulsatile exogenous GH [1,2].
• Body composition, lean mass and bone: robust evidence of fat-free-mass accretion and BMD preservation in healthy elderly, GH-deficient and post-fracture cohorts, including a two-year RCT [2].
• Sleep architecture and recovery research: documented increases in REM and stage-IV slow-wave-sleep duration, of interest in research on age-related sleep fragmentation [3].
• Sarcopenia, frailty and post-injury recovery: Phase II evidence of functional benefit and reduced fall recurrence in elderly post-hip-fracture cohorts [3].
• Pediatric GH deficiency and metabolic models: evaluated for linear-growth response in GHD children and for metabolic-flexibility endpoints in adult populations [1].

References

1. Murphy MG, Plunkett LM, Gertz BJ, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998;83(2):320–325.
2. Nass R, Pezzoli SS, Oliveri MC, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149(9):601–611.
3. Bach MA, Rockwood K, Zetterberg C, et al. The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture. J Am Geriatr Soc. 2004;52(4):516–523.