Background: Oxycodone is widely used as bolus or patient-controlled analgesia (PCA) for control of postoperative pain. The aim of this study was to assess the efficacy and side effects of oxycodone for somatic pain by comparing oxycodone and fentanyl intravenous PCA after orthopedic surgery.Methods: Seventy-three patients undergoing orthopedic surgery were randomly assigned to receive fentanyl or oxycodone using intravenous PCA (potency ratio 1:60). Pain severity at rest and with movement and adverse effects were assessed at 1, 6, 24, and 48 hours after surgery. The PCA dose and patient satisfaction scores were measured at 48 hours after surgery.Results: The resting visual analogue scale (VAS) and moving VAS scores of the oxycodone group were significantly higher than those of the fentanyl group at 6 hours (P = 0.001, P = 0.021), but at 48 hours, the resting and moving VAS of the oxycodone group were significantly lower than those of the fentanyl group (P = 0.014, P = 0.037). There were no significant differences in adverse effects, satisfaction scores, dose of patientcontrolled mode, or total cumulative PCA dose.Conclusions: With a 1:60 ratio of oxycodone to fentanyl when using PCA for pain control after orthopedic surgery, the use of larger doses of oxycodone for 6 hours is effective in controlling early postoperative pain.

Serotonin syndrome is an unexpected adverse reaction of serotonergic medication. Some drugs used by anesthesiologists may cause serotonin syndrome. Serotonin syndrome is known to be related to 5-hydroxytryptamine 1A and 5-hydroxytryptamine 2A agonism. However, recent research has revealed evidence that 5-hydroxytryptamine 3 (5-HT3) antagonism can also play a role in serotonin syndrome. Among the 5-HT3 antagonists, palonosetron is the most highly specific. In this study, we present the first case of fentanyl-and meperidine-induced serotonin syndrome precipitated by palonosetron in general anesthesia.