Anti-hyperalgesic activity of the cox-2 inhibitor lumiracoxib in a model of bone cancer pain in the rat

Chronic pain resulting from metastatic bone cancer remains poorly understood and resistant to treatment. Here we have examined the effect of the novel COX-2 enzyme inhibitor lumiracoxib in a model of bone cancer pain in the rat. Lumiracoxib was administered orally twice daily from day 10 to day 20 after injection of MRMT-1 tumour cells into one tibia. Mechanical hyperalgesia, measured as the reduction in weight-bearing of the ipsilateral limb, and the development of static and dynamic allodynia were significantly inhibited by repeated lumaricoxib administration. A similar reduction in hyperalgesia and allodynia was noted after twice daily administration of another COX-2 inhibitor, valdecoxib, whilst a single acute administration of either drug on day 20, produced no anti-nociceptive activity. Bone mineral density measurements, radiological scores and histological analysis showed that chronic lumaricoxib treatment also significantly attenuated bone destruction induced by tumour cell injection. These data indicate that lumiracoxib and other COX-2 inhibitors have potential therapeutic benefit in the treatment of bone cancer pain. (C) 2003 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.