[Central analgesic effect of paracetamol].

Although biochemical data suggest a direct effect of paracetamol on the CNS, its mode of action is still poorly understood. We investigated the central impact of paracetamol compared to acetylsalicylate in response to transcutaneous electrical nerve stimulation in man. Healthy volunteers received i.v. paracetamol, acetylsalicylic acid, and placebo. Analgesia was assessed by measurement of objective (R-III reflex) and subjective (VAS) pain thresholds. A close correlation was observed between both objective and subjective thresholds. Paracetamol raised the objective and subjective thresholds. In contrast, acetylsalicylic acid had no noticeable effect on either threshold. These data demonstrate a central analgesic effect of paracetamol.