Methadone for Chronic Pain: A Review of Pharmacology, Efficacy, and Safety Concerns.

Purpose of review: Methadone is a synthetic opioid extensively used in opioid use disorder management but is gaining recognition for its unique pharmacological properties that make it a viable alternative for chronic pain management. This review aims to explore methadone's pharmacokinetics, pharmacodynamics, efficacy, and safety profile to assess its potential role in managing chronic pain conditions.

Recent findings: Methadone's dual action as a mu-opioid receptor agonist and NMDA receptor antagonist positions it as an effective option for managing both nociceptive and neuropathic pain. It has shown promising results in cancer pain management, refractory pain, and opioid rotation strategies. Despite its therapeutic advantages, concerns regarding its narrow therapeutic window, variable pharmacokinetics, QT interval prolongation, and risk of respiratory depression highlight the need for careful patient selection and monitoring. New evidence also sheds light on its affordability and efficacy in low-resource settings, as well as its controversial role in mitigating opioid-induced hyperalgesia.

Summary: Methadone offers a unique therapeutic option in chronic pain management due to its multifaceted pharmacological properties. While it provides significant benefits for patients with complex pain syndromes, clinicians must exercise caution due to its safety concerns and variability in individual metabolism. A personalized approach, combined with rigorous monitoring, is essential to optimize its benefits while minimizing risks. Further research is needed to better define its role in chronic pain treatment and address unresolved safety concerns.