[Lys⁵,MeLeu⁹,Nle¹⁰]-NKA(4-10) TFA is a synthetic peptide analog of neurokinin A (NKA), serving as a potent and selective agonist for the NK2 receptor (neurokinin 2 receptor). Its modified structure enhances receptor selectivity, stability, and potency compared to native NKA fragments. This compound is widely used in pharmacological research to investigate NK2-mediated signaling pathways, particularly those involved in smooth muscle contraction, inflammation, pain transmission, and gastrointestinal motility.

The trifluoroacetate (TFA) salt form improves aqueous solubility, making it suitable for both in vitro receptor binding assays and in vivo studies in animal models. It is commonly employed to evaluate agonist activity in functional assays, such as calcium mobilization or cAMP accumulation, and to explore therapeutic potential in conditions like irritable bowel syndrome, chronic pain, and respiratory disorders.