Comparison of the effects of preoperative melatonin or vitamin C administration on postoperative analgesia
What this study found
Preoperative single-dose melatonin (6 mg) or vitamin C (2 g) reduced postoperative pain scores (VAS) within 24 hours and lowered total morphine consumption via PCA compared with placebo. Melatonin: 20.1 ± 6.8 mg; Vitamin C: 22.2 ± 6.5 mg; Placebo: 24.6 ± 8.4 mg (24 h). Both groups required less supplemental diclofenac and experienced fewer nausea/vomiting episodes (p < 0.05). No significant difference between melatonin and vitamin C for pain or morphine use. Melatonin was associated with higher early sedation and longer recovery time. Conclusion: A single preoperative dose of melatonin or…
- Study & population
- Prospective, double-blind, randomized, controlled trial of 165 adults (18–65 years; ASA I–II; both sexes) undergoing elective major abdominal surgery with general anesthesia; three-arm design (melatonin, vitamin C, placebo).
- Intervention
- Preoperative oral melatonin 6 mg (single dose, 1 hour before surgery); preoperative oral vitamin C 2 g (single dose, 1 hour before surgery).
- Key limitation
- Diclofenac used as rescue analgesic rather than opioids; plasma levels of melatonin and vitamin C not measured; heterogeneity of surgical procedures and no sex-specific analyses.
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Open PDFOriginal abstract
The analgesic benefit of melatonin and vitamin C as primary or adjuvant agents has been reported in various studies; however, their analgesic effects in the treatment of postoperative pain remain unclear. Thus, we aimed to evaluate the effect of single preoperative dose of oral melatonin or vitamin C administration on postoperative analgesia. In this study, we recruited 165 adult patients undergoing elective major abdominal surgery under general anesthesia. Patients were randomly divided into three equal (n = 55) groups. One hour before surgery, patients received orally melatonin (6 mg) in group M, vitamin C (2 g) in group C, or a placebo tablet in group P. Pain, sedation, patient satisfaction, total morphine consumption from a patient-controlled analgesia device, supplemental analgesic requirement, and the incidence of nausea and vomiting were recorded throughout 24 h after surgery. The mean pain score and total morphine consumption were found significantly lower in both M and C groups compared with group P (p < 0.001). There were no significant differences between group M and C with respect to pain scores (p = 0.117) and total morphine consumption (p = 0.090). Patients requested less supplemental analgesic and experienced less nausea and vomiting in groups M and C compared with group P. In conclusion, preoperative oral administration of 6 mg melatonin or 2 g vitamin C led to a reduction in pain scores, total morphine consumption, supplemental analgesic requirement, and the incidence of nausea and vomiting compared with placebo.