Nalbuphine, a recently introduced agonist-antagonist analgesic is considered to have analgesic potency similar to morphine in common clinical doses and has been reported to possess an ceiling effect on respiratory depression and to be effective in reversing respiratory depression induced by oxymorphone or hydromorphone. To evaluate the respiratory depression of nalbuphine hydrochloride, we use displacement of CO2 response by a rebreathing method as the index of respiratory depression. Eight healthy male subjects were given the nalbuphine at a dose of 0.1 mg/kg(nalbuphine group) or same volume of normal saline as a placebo(placebo group) intravenously, at interval of 2 weeks by a double blind test. We measured end-tidal PCO2(PETCO2), minute ventilation (VE), tidal volume(VT), and respiratyory frequency(f) at 10 min, 30 min, 60 min and 90 min after the injection. The linear regression equations of VE in response to PCO2 10 min, 30 min, 60 min and 90 min after injection are y=-11.3+0.34X(R=0.66), y=-11.5+0.3X(R=0.53), y=-9.85+0.33X(R =0.61) and y=-11.8+0.37X(R=0.67) in placebo group and y=-11.1+0.30X(R=0.54), y= 13.1+0.35X(R=0.64), y=-11.3+0.33X(R=0.66) and y=-13.4+0.37X(R=0.63) in nalbuphine group.There were no significant differences in the slope of the CO2 response curves between placebo group and nalbuphine group. But there were rightward displacements of the CO2 response curves, which were significant rightward displacements at 60 min and 90 min after the injection(P<0.05). These findings demonstrate that nalbuphine hydrochloride might be a respiratory depressant.
Healthy Volunteers* ; Humans ; Hydromorphone ; Injections, Intravenous* ; Linear Models ; Male ; Morphine ; Nalbuphine* ; Oxymorphone ; Respiratory Insufficiency ; Ventilation

Nalbuphine hydrochloride is a new analgesic structurally related to naloxone, a widely used narotic antagonist, and oxymorphone, a potent narcotic analgesic. Multiple clinical trials have verified the efficacy of nalbuphine in the relief of moderate to severe pain. In general, nalbuphine appears equal to morphine in both medical and surgical use at the same dosage levels and route of administration, although nalbuphine has a slightly longer duration of action. The purpose of this study was to assess the efficacy and side effects of nalbuphine in preoperative medication. Morphine and normal saline as placebo were included for comparison purpose. Eighty four patients who were scheduled to have an elective operation were included in this randomized, double-blind study. The patients received 0.17mg/kg of nalbuphine, 0.12mg/kg of morphine or 1 ml of normal saline respectively. by intramuscular injection one hour before arriving at operation room. Sedation, level of anxiety, emesis, subjective rating on the effect of premedication and side effects were evaluated. The results were as follows: 1) The sedation score was significantly lower in nalbuphine group than placebo group. 2) The level of anxiety was significantly lower in nalbuphine and morphine group than placebo group. 3) The frequency of emesis was not significantly different among three groups. 4) In the subjective rating on the effect of premedication, nalbuphine group was significantly more favorable than placbo group. 5) The side effects such as headache and dizziness were observed, and there were no significant differences in the frequency among three groups. The results indicate that nalbuphine may be recommended as an dffective premedication agent in those situation where opiods are considered as premedication agents.
Anxiety ; Dizziness ; Double-Blind Method ; Headache ; Humans ; Injections, Intramuscular ; Morphine* ; Nalbuphine* ; Naloxone ; Oxymorphone ; Premedication* ; Vomiting