The Effect of Melatonin on Appendectomy Postoperative Pain: A Randomized Clinical Trial

Background: Melatonin is synthesized from the tryptophan amino acid in the pineal gland. Its role in sleep has been confirmed in other studies. Several studies have also shown the effect of melatonin on postoperative pain and sedation. This study aimed to evaluate the effect of melatonin on postoperative pain in patients undergoing appendectomy. Methods: In a double-blind clinical trial, 64 patients aged 18–50 years with ASA I/II anesthesia class who were candidates for appendectomy with general anesthesia were enrolled. The patients were randomly divided into two groups: melatonin and placebo (32 people in each group). The first group received 6 mg of oral melatonin one hour before sleep, while the second group received a placebo. Before surgery and 2, 12, and 24 hours after surgery, patients’ pain was measured using the Visual Analogue Scale (VAS). The Ramsay sedation score measured the patients’ sedation, and rescue analgesia was measured at the above time points. SPSS software was used to analyze the data, and P-values<0.05 were considered significant. Results: Our study showed that pain levels in the melatonin group were lower at the 2nd, 12th, and 24th hours after the appendectomy surgery than in the placebo group. Sedation rates were not significantly different between the two groups. Analgesic consumption was lower in the melatonin group than in the placebo group. Conclusion: Melatonin can reduce the degree of pain (VAS) after appendectomy.