A study of naloxone and doxapram as agents for the reversal of neuroleptanalgesic respiratory depression in the conscious rabbit.

The effectiveness of naloxone and doxapram in reversing the respiratory depressant actions of fentanyl and droperidol in the rabbit has been examined. Both drugs did not reverse fully the depression of respiratory frequency produced by the neuroleptanalgesic agents. Doxapram also failed to reverse fully the depression of minute volume produced by fentanyl and droperidol, although naloxone was adequate in this respect. However, analysis of arterialized venous blood showed that both naloxone and doxapram not only prevented the increase in PCO2 caused by fentanyl and droperidol, but caused also a significant decrease. A reduction in PCO2 was seen also when either naloxone or doxapram was given to untreated rabbits. With doxapram this appeared to be a result of pure respiratory stimulation. Naloxone also produced a reduction in standard bicarbonate.