The relationship between analgesic activity, measured as the hot plate reaction time, and respiratory depression, measured as ventilatory frequency, was investigated in mice for a variety of mu opioid receptor agonists with differing selectivities for mu receptors compared with delta receptors. There was a weak correlation between analgesia and respiratory depression for opioids with the greate...

Opioid treatment of pain is generally safe with 0.5% or less events from respiratory depression. However, fatalities are regularly reported. The only treatment currently available to reverse opioid respiratory depression is by naloxone infusion. The efficacy of naloxone depends on its own pharmacological characteristics and on those (including receptor kinetics) of the opioid that needs reversa...

Pentazocine and pethidine have been compared in the dose ratio 45:75 for their depression of respiration in normal subjects. The respective additive actions of the two drugs were investigated by comparing the effects of a single dose with those of two repeated half-doses. Some degree of ventilatory depression was found consistently. A first half-dose of pentazocine 22.5 mg had a greater effect ...