The dose-related effects of paracetamol on hyperalgesia and nociception in the rat

1 We have studied the effects of 3 low doses of paracetamol (25, 50 and 100 mg kg(-1) p.o.) on inflammatory hyperalgesia, inflammatory oedema, and nociceptive thresholds in rats. 2 At the lower dose (25 mg kg(-1)), paracetamol reduces only central hyperalgesia. 3 At the doses of 50 and 100 mg kg(-1), paracetamol reduces also peripheral hyperalgesia; moreover, it enhances nociceptive thresholds to a mechanical stimulus in the non-inflamed paws. 4 Neither paw inflammatory oedema nor tail nociceptive thresholds to a thermal stimulus were modified by paracetamol administration. 5 Our results suggest that paracetamol can reduce hyperalgesia without affecting physiological nociception and inflammation.