 Laboratory studies with rats have shown that acetaminophen is able to prevent hyperalgesia and block spinal sensitisation induced by NMDA and Substance P18. The same has been demonstrated in a laboratory setting with tramadol, that is able to prevent and reverse hyperalgesic behaviour in rats19. Furthermore it has been shown that the combination of acetaminophen and tramadol is very effective in inhibiting the quantification of proinflammatory mediators PGE2, TNFα in cerebrospinal fluid CSF and in preventing the development of hyperalgesia20. 