The findings from preclinical animal models confirm the peripheral anti-inflammatory/analgesic activity of GW406381 and also suggest contribution of a central site of action to the anti-hyperalgesic efficacy that may not be shared by other COX-2 inhibitors. A central action is consistent with distribution of GW406381 into the CNS in animals. Furthermore, preliminary data from a positron emission tomography study in which 6 healthy male volunteers received a tracer dose of 11C labelled GW406381 indicate that GW406381 is rapidly absorbed into the central nervous system in man.