Discovery and Biological Evaluation of Novel Cyanoguanidine P2X7 Antagonists with Analgesic Activity in a Rat Model of Neuropathic Pain

We disclose the design of a novel series of cyanoguanidines that are potent (IC50 ≃ 10−100 nM) and selective (≥100-fold) P2X7 receptor antagonists against the other P2 receptor subtypes such as the P2Y2, P2X4, and P2X3. We also found that these P2X7 antagonists effectively reduced nociception in a rat model of neuropathic pain (Chung model). Particularly, analogue 53 proved to be effective in the Chung model, with an ED50 of 38 μmol/kg after intraperitoneal administration. In addition compound 53 exhibited antiallodynic effects following oral administration and maintained its efficacy following repeated administration in the Chung model. These results suggest an important role of P2X7 receptors in neuropathic pain and therefore a potential use of P2X7 antagonists as novel therapeutic tools for the treatment of this type of pain.