A 839977 is a P2X7 selective antagonist; it blocks BzATP-evoked calcium influx at recombinant human, rat and mouse P2X7 receptors ( IC 50 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 blockadeare mediated by blocking the release of IL-1beta.