Effect of melatonin on postoperative pain in patients undergoing lower limb surgery: Open-label exploratory randomised study
Melatonin, Postoperative pain, Visual Analogue Scale (VAS), Behavioural Pain Assessment Scale (BPAS), Functional activity score (FAS), Patient satisfaction score (PSS)
Authors:AbstractObjective: To evaluate the effect of melatonin on postoperative pain, perioperative anxiety, functional recovery, and safety in patients undergoing lower limb orthopaedic surgery using the Visual Analogue Scale (VAS), Visual Analogue Scale Anxiety (VAS-A), Functional Activity Score (FAS), WHO causality assessment scale. Methods: Patients aged 20–60 years with ASA grade I–II were randomised into two groups (n=40 each). Group A received oral melatonin 6 mg one hour preoperatively and nightly for five postoperative days; Group B served as the control. All participants received intramuscular diclofenac 50 mg twice daily for five days. Anxiety was assessed using VAS-A from baseline to 24 hours postoperatively. Pain was evaluated using VAS and Behavioural Pain Assessment Scale (BPAS), and functional recovery using FAS, from baseline to 120 hours. Patient satisfaction assessed periodically. Data were analysed using repeated-measures ANOVA with Bonferroni post hoc test and unpaired t-test. Findings: Baseline characteristics were comparable between groups. Melatonin significantly reduced VAS pain scores at rest and during movement from 2 hours postoperatively. Anxiety scores decreased within 1 hour of administration and remained significantly lower at 12 and 24 hours. BPAS scores improved from 12 hours onward, while FAS demonstrated better recovery at 48 hours compared with control. At 120 hours, 80% of patients receiving melatonin reported excellent satisfaction compared with 35% in the control group. Adverse effects were mild, comparable between groups. Conclusion: Melatonin may be an effective and safe adjuvant to NSAIDs for reducing postoperative pain and anxiety and improving functional recovery following lower limb orthopaedic surgery.
Received-18-05-2026 Revised-20-06-2026 Accepted-25-06-20.26
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