Ultra-low-dose Naloxone As an Adjuvant to Patient Controlled Analgesia (PCA) With Morphine for Postoperative Pain Relief Following Lumber Discectomy: A Double-blind, Randomized, Placebo-controlled Trial

Background: Lumbar discectomy is one of the most commonly performed neurosurgical procedures. Many patients experience postoperative pain after lumbar discectomy. This study evaluated the effect of ultra-low-dose naloxone infusion on pain intensity after lumbar discectomy in individuals receiving patient-controlled analgesia (PCA) with morphine.

Materials And Methods: In a double-blind, randomized, controlled trial, a total of 80 patients scheduled for open discectomy was randomly assigned to receive naloxone (group N) or placebo (group P). After surgery, all patients were connected to a morphine PCA pump. Both groups received 500 mL of normal saline using a continuous infusion pump through a separate intravenous line for 24 hours. However, group N received a total dose of 0.25 μg/kg/h naloxone, which was added to the normal saline infusion. All patients were asked to grade the intensity of their pain, severity of nausea, vomiting, and pruritus on a 0 to 10 visual analog scale before being discharged from the postanesthesia care unit and at 1, 6, 12, and 24 hours postoperatively.

Results: It was observed that both groups had a statistically significant (P<0.01) time trend difference for pain, nausea, and pruritus scores. A significant difference was found between the 2 groups in terms of intensity of pain, nausea, and pruritus, with the naloxone group experiencing a lower level in comparison with the placebo group. Moreover, the median (interquartile range) of morphine consumption after surgery for patients who received naloxone was 26 (24.25 to 28) mg, which is significantly (P<0.001) lower than for the placebo group, which had a median (interquartile range) of 34 (32 to 36) mg.

Conclusions: It is concluded that infusion of ultra-low-dose naloxone (0.25 μg/kg/h) along with morphine PCA can significantly reduce pain intensity, morphine consumption, and opioid-induced nausea and pruritus after lumbar discectomy.