Comparison of the anti-hyperalgesic and anti-inflammatory effects of meloxicam in the rat

Meloxicam, a non-steroidal anti-inflammatory drug, is a preferential inhibitor of cyclooxygenase-2 (COX-2) and has demonstrated potent analgesic and anti-inflammatory activities after oral administration. In order to dissociate these effects, the present study was carried out to compare the antihyperalgesic and anti-inflammatory effects of meloxicam in animal models. The anti-hyperalgesic effect was evaluated using the carrageenan-evoked thermal hyperalgesia, whereas anti-inflammatory activity was characterized using carrageenan-induced acute paw edema in rats. Meloxicam (0.32 - 32 mg/kg, p.o.) was administered and effects were determined. Meloxicam was able to produce both anti-hyperalgesic and anti-inflammatory effects, reaching a maximum of about 63% in both models. However, doses required for production of anti-inflammatory activity were lower (EC₅₀ 1.8 ± 0.3 mg/kg) than those required for the anti-hyperalgesic effect (EC₅₀ 5.3 ± 1.0 mg/kg). These results are in agreement with a dissociation of the anti-inflammatory and analgesic activities of non-steroidal anti-inflammatory drugs and COX-2 inhibition seems to be associated mainly with anti-inflammatory activity.