Doxapram antagonism of meperidine-induced respiratory depression

The intramuscular injection of meperidine (1 mg./kg.) alone causes significant respiratory depression, and doxapram (2 mg./kg.) alone causes significant respiratory stimulation, as evidenced by their ability to shift the carbon dioxide (CO2) response curve to the right and left, respectively. When given together, the mixture of the two drugs does not cause any significant respiratory depression, as indicated by the absence of a significant shift in the CO2 response curve to the right. This mixture has possible clinical usefulness in providing postoperative analgesia without respiratory depression.