Preliminary study of epidural nalbuphine in treatment of post operative pain: a comparison with equipotent dose of epidural morphine.

Epidural analgesia was used in 45 patients submitted to upper abdominal surgery. In 30 of them 0.15 mg/kg nalbuphine (EN group) was injected and in the remained, an equipotent dose of 0.1 mg/kg of preservative free morphine (EM group) was used. The patients were observed concerning the severity of pain before and after narcotic administration, duration of analgesia, occurrence and severity of side effects among them. The severity of pain was stated by the McGill pain score (from 0 to 5). Duration of analgesia was defined as the time interval from pain relief after narcotic administration until requirement of an additional epidural narcotic injection. The adequacy of ventilation was estimated by sequential measurements of arterial PCO2. Pain relief was excellent in all patients after both narcotics administration. The analgesia time was significantly longer with epidural morphine than in the EN patients. Besides drowsiness, the other side effects incidence was lower with epidural nalbuphine than with epidural morphine. Two patients in the EM group presented clinical respiratory depression, showing a significant increase in arterial PCO2. We believe that the lack of respiratory depression seen in EN group is a consequence of the rostral diffusion of the drug, which reaches high concentrations at the respiratory centers level and a direct antagonist action upon them. Our results showed that epidurally administered nalbuphine provides a good analgesia, with minor side effects and favorably compares with epidural morphine.