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 in opioid-addicted patients who were admitted to orthopedic department for surgery due to bone fractures. METHOD: Male adults who were addicted to opioids, aged 18 to 79 years were enrolled (n=96) and randomized into two oral doses (4 & 8 mg) of ondansetron (n=32) and placebo (n=32). The vital signs and withdrawal symptoms and the frequency requirement of fentanyl were recorded during anesthesia, and opioid (pethidine) analgesic were received the period of recovery. Outcome parameters were analyzed for reduction of withdrawal symptoms in adult addicted patients. RESULTS: We indicated that ondansetron demonstrated significant differences with few vital outcomes including systolic blood pressure (BPS) 20 (BPS 3) and 50 min (BPS 4) after injection of ondansetron during the period of the 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 were 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 a few evidence for beneficial treatment of ondansetron for control of withdrawal symptoms and pain in addicted patients, and more clinical studies are suggested in this regard.