Impact of Ondansetron on Withdrawal Signs, Fentanyl Requirement and Pain Relief in Opioid-addicted Patients under General Anesthesia.

Background: Serotonin 5-HT3 receptor antagonists such as ondansetron have been investigated to attenuate opioid withdrawal signs in studies.

Objective: Therefore, we designed a randomized double-blinded placebo-controlled trial to evaluate this effect on opioid-addicted patients who were admitted to the orthopedic department for surgery due to bone fractures.

Methods: Male adults who were addicted to opioids, aged 18 to 79 years were enrolled (n=96) and randomized into intravenous doses (4 & 8 mg) of ondansetron (n=32) and placebo (n=32). The vital signs, withdrawal symptoms and the frequency requirement of fentanyl were recorded during anesthesia, and opioid (pethidine) analgesic was received during the recovery period. Outcome parameters were analyzed for reduction of withdrawal symptoms in addicted adults.

Results: We indicated that ondansetron demonstrated significant differences with few vital outcomes including systolic blood pressure (SBP) 20 (SBP3) and 50 min (SBP4) after injection of ondansetron during the period of surgery. Ondansetron could also significantly reduce the frequency requirement of fentanyl at 20 min (dose 3) in general anesthesia. Furthermore, requirement for further administration of opioid analgesic drugs such as pethidine was significantly reduced in the ondansetron groups. Objective opioid withdrawal scale (OOWS) results indicated that few clinical parameters including tremor, hot and cold flushes and anxiety were significantly attenuated in addicted patients who received ondansetron.

Conclusion: This study demonstrated supporting evidence for the beneficial treatment of ondansetron for the control of withdrawal symptoms and pain in addicted patients, and more clinical studies are suggested in this regard.