Netupitant (CID-6451149) is a highly potent and selective, orally active neurokinin-1 receptor antagonist with Ki of 0.95 nM.IC50 value: 0.95 nM (Ki) [1]Target: NK1 receptorin vitro: Netupitant also dose-dependently inhibited the SP response as expected from an NK1 receptor antagonist. Importantly, when both palonosetron and netupitant were present, they exhibited an enhanced inhibition of the SP response compared to either of the two antagonists alone [2].in vivo: In mice the intrathecal injection of SP elicited the typical scratching, biting and licking response that was dose-dependently inhibited by Netupitant given intraperitoneally in the 1-10mg/kg dose range. In gerbils, foot tapping behavior evoked by the intracerebroventricular injection of a NK(1) agonist was dose-dependently counteracted by Netupitant given intraperitoneally (ID(50) 1.5mg/kg) or orally (ID(50) 0.5mg/kg) [3].

References:
[1]. Hoffmann T, et al. Design and synthesis of a novel, achiral class of highly potent and selective, orally active neurokinin-1 receptor antagonists. Bioorg Med Chem Lett. 2006 Mar 1;16(5):1362-5.
[2]. Stathis M, et al. Inhibition of substance P-mediated responses in NG108-15 cells by netupitant and palonosetron exhibit synergistic effects. Eur J Pharmacol. 2012 Aug 15;689(1-3):25-30.
[3]. Rizzi A, et al. In vitro and in vivo pharmacological characterization of the novel NK1 receptor selective antagonist Netupitant. Peptides. 2012 Sep;37(1):86-97.
[4]. Ajit G. Thomas, et al. Netupitant and palonosetron trigger NK1 receptor internalization in NG108-15 cells. Exp Brain Res. 2014; 232(8): 2637–2644.