• Yoshihiro Kitagawa, Isao Tamai, Yuji Hamada, Kenji Usui, Masashi Wada, Masahiro Sakata, and Mutsuyoshi Matsushita.
• Central Pharmaceutical Research Institute, Japan Tobacco Inc., Osaka, Japan. yoshihiro.kitagawa@jt.com
• J. Pharmacol. Sci. 2013 Jan 1;122(2):128-37.

AbstractChronic pain refractory to non-steroidal anti-inflammatory drugs (NSAIDs) is a major problem and drugs for such pain are needed. Many studies suggest that transient receptor potential vanilloid type 1 (TRPV1) is associated with NSAID-refractory chronic pain. Therefore, we investigated the involvement of TRPV1 in NSAID-refractory chronic pain using experimental models for NSAID-refractory chronic pain reflecting severe arthritic and postherpetic pain. The selective TRPV1 antagonist JTS-653 {(3S)-3-(hydroxymethyl)-4-(5-methylpyridin-2-yl)-N-[6-(2,2,2-trifluoroethoxy)pyridin-3-yl]-3,4-dihydro-2H-benzo[b][1,4]oxazine-8-carboxamide} reversed mechanical hyperalgesia on day 7 after injection of complete-Freund-adjuvant into the hindpaw in rats at 0.3 mg/kg, whereas indomethacin showed no effect. JTS-653 reduced chronic pain at 0.3 mg/kg in herpes simplex virus-1-inoculated mice that has been reported as NSAID-refractory pain. JTS-653 partially attenuated mechanical hyperalgesia in the L5 spinal nerve ligation model in rats at 0.3 mg/kg, whereas indomethacin showed no effect. Both JTS-653 and indomethacin reduced formalin-induced pain in the second phase, whereas they showed no effect in the first phase. JTS-653 did not affect the nociception of noxious thermal and mechanical stimuli and motor coordination in normal rats. These findings demonstrate the TRPV1 involvement in NSAID-refractory chronic pain reflecting severe arthritic and postherpetic pain. TRPV1 antagonists would be useful for the treatment of NSAID-refractory chronic pain.

33 keywords...

hide…