An Insight about Opioid Use Disorder; Pathophysiology, Stages and Neurocircuitry Effects

Abstract

Accurate estimation of the population-based prevalence of OUD is challenging. The availability and quality of data on OUD varies geographically. The types of opioids used and the typical routes of administration vary between countries and have changed over time. The likelihood of OUD following opioid use is high compared with most other drugs. Some individuals are highly vulnerable to OUD following opioid use, whereas others do not develop OUD and cease within a year of first use. A complex interplay of structural, social, developmental and behavioral risk factors is likely to have a role in the development of OUD. OUD has a moderate to high heritability. Several consequences of prescribed and non-medical opioid use cause substantial burden to the individual, families, and the broader community. Building on conceptual frameworks derived from neurobiology from animal models, clinical brain imaging studies and social psychology, a three-stage cycle of OUD has been hypothesized, consisting of binge/intoxication, withdrawal/negative affect and preoccupation/ anticipation stages. Dramatic tolerance (that is, a lower response to a drug following repeated administration of the drug or the need for larger doses to produce the same effect) develops to the analgesic, euphorigenic, sedative and other effects of opioids, including their lethal effects, and can develop after a single administration. Symptoms of physical withdrawal in humans include piloerection, chills, insomnia, diarrhea, nausea, vomiting and aches, and the severity and duration vary based on the dose and duration of opioid exposure and the pharmacological properties of the opioid used, including efficacy and pharmacokinetics.