The Effect of Adding Low-Dose Naloxone to Intrathecal Morphine on Postoperative Pain and Morphine Related Side Effects after Cesarean Section: A Double-Blind, Randomized, Clinical Trial

BACKGROUND: Nowadays, spinal anaesthesia is a suitable choice for most elective and emergency cesarean section (C-section) deliveries. AIM: This study aimed to determine the effect of adding low-dose naloxone to intrathecal morphine on postoperative pain and morphine related side effects after C-section. MATERIAL AND METHODS: In the present double-blind, randomised clinical trial, 70 women aged over 18 years, who were candidates for elective medical C-section under spinal anaesthesia were selected and randomly assigned to either the study group or the control group. For spinal anaesthesia, 10 mg of Bupivacaine plus 100 μg of morphine was administered for all patients. However, patients in the study group received 20 µg of naloxone intrathecally; but the patients in the control group only received normal saline as a placebo. After surgery, patient-controlled analgesia (PCA) pump with paracetamol (Apotel®) was connected to each patient. The intensity of postoperative pain in the patients was evaluated and recorded using Visual Acuity Screening (VAS) at 2, 4, 6 and 24 hours after the surgery. The patients were also examined for postoperative nausea and pruritus. RESULTS: Regardless of the groups to which the patients were assigned, a significant difference in pain intensity was observed during the study period (time effect; p < 0.001). Although the intensity of pain was lower in the study group, the difference was not statistically significant (group effect; p = 0.84). Also, there was no group time interaction between pain intensity and the times studied (p = 0.61). The incidence rates of postoperative nausea and pruritus were significantly lower in the study group compared to the control group (p < 0.001). CONCLUSION: According to the results of this study, adding low dose naloxone to intrathecal morphine did not significantly change postoperative pain intensity in the patients undergone elective C-section using spinal anaesthesia; however, significantly decreased the severity of postoperative nausea and pruritus.