Effect of Oral Melatonin on Postoperative Analgesia After Thoracotomy in Infants

Overview

Thoracotomy pain is one of the severest pain that should be taken seriously, especially in children. (1) Inadequate postoperative pain management can compromise respiratory function, delay postoperative extubation, increase the cost and delay hospital discharge. Opioids are the most commonly used analgesics to manage postoperative pain; however, they have many possible unfavorable side effects, such as nausea, vomiting, pruritus, and respiratory depression. (3) Melatonin is an endogenous indoleamine secreted by the pineal gland. It has several important physiological functions, including regulation of the circadian rhythms, modulation of season changes, antioxidant, anti-inflammatory, and anticonvulsant effects. (4)

The analgesic effect of melatonin may be referred to as Gi-coupled melatonin receptors, to Gi-coupled opioid-l-receptors or gamma-aminobutyric acid (GABA) receptors with a consequential reduction in anxiety and pain. (5) Gitto and co-workers(6) hypothesized that melatonin may have beneficial effects as an analgesic effect in preterm newborns that are subject to painful procedures, such as endotracheal intubation and mechanical ventilation without detected side effects. Pro-inflammatory and anti-inflammatory cytokines related to pain were more in the common sedation and analgesia group than in melatonin-treated infants suggesting the use of melatonin as an adjunct analgesic therapy during procedural pain. (6) Therefore Melatonin may be a useful perioperative drug as it does not have any known undesirable serious adverse effects. (7) To the best of investigators' knowledge, this is the first study investigating the effect of melatonin on postoperative pain scores after thoracotomy in infants.