Fig. 4. SR-8993 is a new specific and potent NOP-R agonist.
(A) SR-8993 is characterized by unusually high selectivity for the NOP-R over the closely related opioid receptors. Structure and physical and pharmacokinetic characteristics of SR-8993 are shown. (B to D) SR-8993 dose-response curves in human embryonic kidney (HEK) cells expressing the NOP/NOP-R (B), the μ opioid receptor (C), and the κ opioid receptor (D).