A preclinical comparison between different opioids: antinociceptive versus adverse effects

ED50's for the occurrence of side-effects were compared to ED50's in behavioural pain tests. Fentanyl had a strong analgesic potency and, compared to other opioids, an acceptable side-effect profiling at analgesic ED50's. Also consistent was the ceiling effect of buprenorphine implying an increased safety margin for side-effects, but a decreased analgesic efficacy. Differences between opioids as observed in this study can have important indications for their use in acute as well as in the onset of chronic treatments.