Purity >98%. A-804598 is a potent and selective competitive antagonist of the purinergic P2X7 receptor, a ligand-gated ion channel, with IC50 values of 9.9 and 10.9 nM in 132N1 cells transfected with the rat or mouse receptor, respectively. It inhibits IL-1Beta release in human THP-1 cells stimulated with LPS and IFN-Gamma (IC50 = 8.5 nM). A-804598 is selective for P2X7 receptors over other P2X and P2Y receptors at concentrations up to 100 μM and over many G protein-coupled receptors, enzymes, transporters, and ion channels. A-804598 (25 mg/kg) prevents footshock-induced increases in IL-1Beta mRNA in the paraventricular nucleus of the rat hypothalamus.