Antagonism between tilidine and naloxone on cerebral potentials and pain ratings in man.

The effects of the opioid tilidine and the opiate antagonist naloxone on somatosensory evoked potentials (SSEP) and pain ratings (E), elicited by electrical skin stimuli with randomized intensities, were investigated for different, orally administered tilidine and naloxone combinations in a double-blind Latin square design in 15 healthy humans. A high correlation between SSEP amplitudes and E was found for all treatments investigated. Tilidine (100 mg) decreased both SSEP amplitudes and E by about 25% compared to the placebo. No significant differences were found between the analgesic effects of tilidine and TN8 (tilidine 100 mg; naloxone 8 mg). The effects of both treatments were significantly different from those of the naloxone, placebo and TN32 treatments (tilidine 100 mg; naloxone 32 mg), indicating a marked naloxone-induced reversal of tilidine analgesia. Naloxone (32 mg) increased the SSEP amplitudes. No naloxone-induced hyperalgesia was seen in the pain ratings.