N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyrazine -1(2H)-carbox-amide (BCTC), a novel, orally effective vanilloid receptor 1 antagonist with analgesic properties: II. in vivo characterization in rat models of inflammatory and neuropathic pain.
The vanilloid receptor 1 (VR1) is a cation channel expressed predominantly by nociceptive sensory neurons and is activated by a wide array of pain-producing stimuli, including capsaicin, noxious heat, and low pH. Although the behavioral effects of injected capsaicin and the VR1 antagonist capsazepine have indicated a potential role for VR1 in the generation and maintenance of persistent pain states, species differences in the molecular pharmacology of VR1 and a limited number of selective ligands have made VR1 difficult to study in vivo. N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropryazine-1(2H)-carbox-amide (BCTC) is a recently described inhibitor of capsaicin- and acid-mediated currents at rat VR1. Here, we report the effects of BCTC on acute, inflammatory, and neuropathic pain in rats. Administration of BCTC (30 mg/kg p.o.) significantly reduced both mechanical and thermal hyperalgesia induced by intraplantar injection of 30 micro g of capsaicin. In rats with Freund's complete adjuvantinduced inflammation, BCTC significantly reduced the accompanying thermal and mechanical hyperalgesia (3 mg/kg and 10 mg/kg p.o., respectively). BCTC also reduced mechanical hyperalgesia and tactile allodynia 2 weeks after partial sciatic nerve injury (10 and 30 mg/kg p.o.). BCTC did not affect motor performance on the rotarod after administration of doses up to 50 mg/kg p.o. These data suggest a role for VR1 in persistent and chronic pain arising from inflammation or nerve injury.
Pomonis
James D
JD
Pudue Pharma Discovery Research, 6 Cedarbrook Dr., Cranbury, NJ 08512, USA.
Harrison
James E
JE
Mark
Lilly
L
Bristol
David R
DR
Valenzano
Kenneth J
KJ
Walker
Katharine
K
D000700:Analgesics / Q000009:adverse effects / Q000627:therapeutic use*; D000818:Animals; D001259:Ataxia / Q000139:chemically induced; D002211:Capsaicin; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D007249:Inflammation / Q000188:drug therapy / Q000209:etiology; D008297:Male; D009417:Nerve Tissue / Q000293:injuries; D010146:Pain / Q000188:drug therapy*; D017288:Pain Threshold; D011719:Pyrazines / Q000009:adverse effects / Q000627:therapeutic use*; D011725:Pyridines / Q000009:adverse effects / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000037:antagonists & inhibitors*
D000700:Analgesics; C475772:N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carboxamide; D011719:Pyrazines; D011725:Pyridines; D011955:Receptors, Drug; D002211:Capsaicin