A 839977 is a P2X7 selective antagonist; it blocks BzATP-evoked calcium influx at recombinant human, rat and mouse P2X7 receptors (IC50 values are 20 nM, 42 nM and 150 nM respectively) and reduces inflammatory and neuropathic pain in animal models; the antihyperalgesic effects of P2X7 receptor blockade are mediated by blocking the release of IL-1beta.