C5aR1 antagonist 2 (Compound 6a), an orally active antagonist of C5a receptor 1 (C5aR1), effectively inhibits increases in neutrophil counts induced by C5a. This compound demonstrates potency in both DISCO and migration assays, with IC50 values of 21 and 3 nM, respectively. It is utilized in the study of acute and chronic inflammatory diseases [1].

C5aR1 antagonist 2, administered orally at a dose range of 1-10 mg/kg once, effectively blocks CD11b upregulation in C5a-induced neutrophilia in rats in a dose-dependent manner [1]. It also inhibits C5a-induced neutrophilia in female Sprague-Dawley rats with hC5aR1 knockout [1]. Pharmacokinetic analysis [1] indicates that at a 10 mg/kg oral dose, the compound exhibits an AUC 0-last of 35700 ng·h/mL, C max of 3610 ng/mL, T max of 2.5 h, clearance (CL) of 39 mL/(min*kg), volume of distribution (V ss_obs) of 7.1 L/kg, and a half-life (t 1/2) of 3.7 hours.