Postoperative Analgesic Efficacy of Nefopam after Anorectal Surgery: A Retrospective Observational Study

Objective To examine the effectiveness of nefopam on postoperative pain control after anorectal surgeries. Methods We retrospectively reviewed the electronic medical records of patients who underwent anorectal surgeries from January 2019 to March 2022 at two medical centers. The data were divided into nefopam and conventional groups. The primary outcome was the number of patients who requested additional opioids in the 24-h postoperative period. The secondary outcomes were numeric rating pain scores (NRPS) within a 24-h postoperative period and analgesic drugs-related side effects. Results Eighty-seven patients in the conventional group and 60 in the nefopam group were recruited. The nefopam group reported less additional opioid consumption than the conventional group in all dimensions of analysis, including overall, adjusted to anesthetic techniques and types of surgery. However, these did not reach statistical significance (P = 0.093). Only patients in the nefopam group who underwent hemorrhoidectomy under TIVA or spinal anesthesia significantly required fewer additional opioids (P = 0.016, 60% mean difference). Similarly, the 24-h postoperative morphine consumption was lower in the nefopam group (mean difference = −3.4, 95%CI: 0.72,6.08). Furthermore, significantly lower NRPS were reported in the nefopam group during the 12-18 h postoperative period (P = 0.009). On the other hand, analgesic drugs related side effects were similar in both groups. Conclusions The administration of nefopam after major anorectal surgery is beneficially evident in reducing postoperative opioid requirements.