Chapter 38 - Methadone Usage, Misuse, and Addiction Processes: An Overview

Abstract

Opioid abuse and addiction remain a serious social and health problem, especially with the dramatic increase in the use of prescription opioids. This chapter begins with an overview of the neural mechanisms underlying opioid reward, tolerance, dependence, and addiction, followed by a review of the history of the discovery of methadone pharmacotherapy. The author then reviews the rationale for methadone treatment, and the use and misuse of methadone in the treatment of pain and opioid addiction. Research shows that opioids predominantly target brain gamma-butyric acid, dopamine, and norepinepherine neurons, causing a series of enduring neuroadaptive changes that result in opioid dependence and addiction. Methadone treatment was discovered from unexpected clinical observations 50years ago. Since then, methadone has been shown to be safe and effective in reducing illicit opiate use and in relieving craving and withdrawal syndromes. Therefore, it has been widely used in opioid detoxification and maintenance treatment. Future major challenges include how to deliver the methadone or other agonist therapies to more patients and how to control misuse and overdose of methadone and/or other prescription opioids.