A dose-response relationship study depicted that prophylactic use of 0.280 mg/kg intravenous nalbuphine is beneficial to reduce pain during the awakening period in people undergoing laparoscopic total hysterectomy. The median effective dose (ED50, 95% confidence interval) of nalbuphine as an analgesic for prophylaxis during awakening phase of patients was found to be 0.125 (0.108, 0.145).

In this randomized, double-blind, controlled clinical trial, Min Wang et al. aimed to explore the impact of different doses of nalbuphine on postsurgery analgesia and adverse reactions in 120 patients scheduled to undergo laparoscopic gynecological surgery. Participants (aged ≥ 45 years) were segregated into six groups: (i) Group C (control), and (ii) Group P (5 different doses of nalbuphine) with 20 people per group.

The nalbuphine doses in group P were in an equally proportional series (groups P1, P2, P3, P4, and P5 were given doses of 0.280, 0.200, 0.140, 0.100, and 0.070 mg/kg, respectively), diluted to 20 mL with saline and given 5 minutes prior to anesthesia induction. A similar volume (20 mL) of saline was given to group C 5 minutes prior to anesthesia induction. The numeric rating scale (NRS) of people during awakening and after surgery, the number of postoperative salvage analgesia, and the incidence of postsurgery adverse effects were recorded.

With the aid of point-slope method, the ED50 (95% confidence interval) of nalbuphine in preventing pain during awakening period was calculated and was found to be 0.125 (0.108, 0.145) mg/kg. The NRS scores differed among the six groups at 30 minutes and 1 hour after extubation. The pairwise comparisons between groups demonstrated that, at 30 minutes after extubation, the NRS scores of groups P4, P5, and C were greater in comparison with group P1.

Compared with group P2, the groups P5 and C exhibited higher NRS scores. At 1 hour following extubation, the NRS scores of groups P1 and P2 were reduced when compared to group P4. In comparison with the control group, only group P1 illustrated a reduced cough score. No differences were witnessed in the other groups. There were no differences in sedation score at 10 minutes following extubation, the occurrence of adverse events at 24 hours postoperatively, or the number of remedial analgesics at 24 hours postoperatively.

The ED50 of nalbuphine as a prophylactic in minimizing pain during recovery was 0.125 mg/kg. Nalbuphine at doses of 0.140, 0.200, and 0.280 mg/kg prevented pain in the waking phase when compared to the control group. Among these doses, 0.280 mg/kg nalbuphine was found to be the best. With 0.280 mg/kg nalbuphine, the occurrence of cough episodes was reduced during extubation and the postsurgery analgesic effect was good. But, it is pivotal to pay attention to the occurrence of side effects, concluded the study authors.