Comparative Investigation of the Effects of Adenosine Triphosphate, Melatonin, and Thiamine Pyrophosphate on Amiodarone-Induced Neuropathy and Neuropathic Pain in Male Rats

Background: Amiodarone is a widely used class III antiarrhythmic agent, but its use can lead to peripheral neuropathy mediated by mitochondrial dysfunction, oxidative stress, and neuroinflammatory injury, while effective preventive options remain limited. Agents that support mitochondrial energy metabolism, sustain redox balance, and modulate inflammation, including adenosine triphosphate (ATP), melatonin, and thiamine pyrophosphate (TPP), may counteract these mechanisms; however, their relative neuroprotective potential in amiodarone-induced neuropathy remains unclear. This study aimed to comparatively evaluate the effects of ATP, melatonin, and TPP on amiodarone-induced peripheral neuropathy and neuropathic pain in rats. Methods: Thirty male albino Wistar rats were assigned to five groups: healthy; amiodarone (50 mg/kg/orally); amiodarone + ATP (5 mg/kg/intraperitoneally); amiodarone + melatonin (10 mg/kg/orally); or amiodarone + TPP (20 mg/kg/intraperitoneally). Treatments were given once daily for 14 days. Oxidative stress indices (malondialdehyde (MDA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT)) and proinflammatory cytokines (tumor necrosis factor-alpha (TNF-α), interleukin-1 Beta (IL-1β), interleukin-6 (IL-6)) were quantified in sciatic nerve by Enzyme-Linked Immunosorbent Assay (ELISA). Paw withdrawal thresholds were measured with the Randall-Selitto test before and after treatment. Histopathology was performed using Hematoxylin-eosin staining. Results: Amiodarone exposure resulted in pronounced elevations in MDA and proinflammatory cytokine levels, accompanied by significant reductions in tGSH, SOD, CAT activities, and paw withdrawal thresholds. ATP, melatonin and TPP ameliorated these alterations to varying degrees. Among them, TPP provided the most robust antioxidant and anti-inflammatory effects, followed by ATP and melatonin. Histopathological examination confirmed most severe axonal degeneration, interstitial edema and Schwann cell proliferation in the amiodarone group, with substantial amelioration in the TPP-treated rats. Conclusions: Amiodarone induces neuropathic pain through oxidative and inflammatory injury to peripheral nerves. TPP exhibited superior neuroprotective efficacy compared with ATP and melatonin, highlighting its potential as a candidate therapeutic agent for amiodarone-related neuropathy. Further clinical research is warranted to support translational application of these findings. © 2025 by the authors.