Relamorelin(BIM28131, RM131) is a selective and potent ghrelin/growth hormone secretagogue receptor (GHSR) agonist with high affinity for GHS-1a receptor (Ki value is 0.42 ± 0.063 nM). Relamorelin(BIM28131, RM131) is also a centrally permeable pentapeptide analog that can increase growth hormone levels and accelerate gastric emptying, and has the potential to study cachexia.

native ghrelin:1.12 nM (Ki), native ghrelin:4.2 nM (EC50), GHS-1a:0.42 nM (Ki), GHS-1a receptor:0.71 nM (EC50)

Relamorelin (BIM28131, RM131) binds to the known ghrelin receptor (GHS-1a) with subnanomolar affinity (inhibition constant, 0.42 ± 0.063 nM), approximately three-fold higher than the affinity of native ghrelin (inhibition constant, 1.12 ± 0.17 nM); relamorelin (BIM28131, RM131) is six times more potent (EC50, 0.71 ± 0.09 nM) than native ghrelin (EC50, 4.2 ± 1.2 nM) in activating the GHS-1a receptor as assessed by in vitro calcium mobilization. [2]

METHODS: C57BL6/J wt and GHR ko mice were treated with daily subcutaneous injections of rat ghrelin (5,000 nmol/kg) and RM-131 (50 or 500 nmol/kg), and the chronic effects of RM-131 on body weight, body composition (fat and lean mass), and food intake were measured.
RESULTS Mice treated with 500 nmol/kg RM-131 showed a greater increase in food intake. [1]
Relamorelin(BIM28131, RM131) has a higher enzymatic stability in plasma than native ghrelin (half-life in rat plasma is 24 h vs. 1.9 h, respectively). hours), and when injected intravenously, its circulation half-life is prolonged 10-fold compared to native ghrelin.[2]