ObjectivesA double-blind randomised study to evaluate the opioid sparing effect and safety of nefopam when administered via intravenous patient controlled analgesia (PCA) with fentanyl.MethodsPatients planned for elective open laparotomy, were randomly assigned to receive into fentanyl 25 µg/ml (SF group) or nefopam 2.4 mg/ml plus fentanyl 25 µg/ml (NF group). Patients were assessed before surgery and for 24 h postoperatively.ResultsTotal PCA fentanyl consumption was significantly lower in the NF group (n = 35) than the SF group (n = 36). Pain scores were significantly lower and patients’ satisfaction with treatment significantly better in the NF group than the SF group. Dry mouth and dizziness were significantly more frequent in the NF group than the SF group. There were no other statistically significant between-group differences in the incidence of adverse events.ConclusionsIntravenous PCA using nefopam + fentanyl following laparotomy has an opioid sparing effect and is associated with a low incidence of some of the typical opioid related adverse events.Trial registryClinicaltrials.gov Registration No: NCT02596269