Notes: Aticaprant is a κ-opioid receptor (KOR) antagonist (Ki = 0.807 nM).{61978} It is selective for KOR over the μ- and δ-opioid receptors (Kis = 24 and 155 nM, respectively). Aticaprant reverses U-69593-induced decreases in nocifensive behavior in the formalin test in rats (ED50 = 0.4 mg/kg). It also reverses U-69593-induced disruptions in prepulse inhibition in rats in a dose-dependent manner. Aticaprant (10 mg/kg) reduces immobility time in the forced swim test in mice. It reduces alcohol self-administration and the progressive ratio breakpoint in rats when administered at a dose of 10 mg/kg.