Combination of low-dose nalbuphine and morphine in patient-controlled analgesia decreases incidence of opioid-related side effects.

BACKGROUND/PURPOSE The addition of ultra-low-dose naloxone to patient-controlled analgesia (PCA) with morphine reduces opioid-related side effects. Nalbuphine, a mixed opioid agonist-antagonist, may be able to attenuate opioid-related side effects. The goal of the present study was to investigate the effect of combined low-dose nalbuphine and morphine in PCA for postoperative pain control after gynecological surgery. METHODS This randomized, double-blind, controlled study enrolled 174 female patients who were undergoing total abdominal hysterectomy, myomectomy, or ovarian tumor excision. In the control group, the PCA formula was 1 mg/mL pure morphine. In the study group, the PCA formula was 1 mg/mL morphine and 10 microg/mL nalbuphine (1:100). Numerical rating score, PCA requirement, nausea, vomiting, use of antiemetics, pruritus, use of antipruritics, and opioid-related adverse events were investigated at 1, 2, 4, and 24 hours postoperatively. RESULTS One hundred and sixty-nine patients completed the study: 86 in the control group and 83 in the study group. The incidence of nausea was lower in the study group (41%) than in the control group (65%). The incidence of vomiting, use of antiemetics, pruritus, and use of antipruritics did not differ between the two groups. The numerical rating pain score and PCA requirements were not significantly different between the two groups. CONCLUSION Combination of low-dose nalbuphine and morphine in PCA decreases the incidence of opioid-related nausea, without affecting the analgesia and PCA requirement. This novel combination can improve the quality of PCA used for postoperative pain control after gynecological surgery.