Adjunct Therapy in Opioid Pain Management: A Scoping Review

Opioids are among the most prescribed analgesics for treatment of pain. An adjunct is "an additional treatment used to increase the efficacy or safety of a primary treatment." Various classes of drugs have been used as adjuncts to opioids, with the potential to reduce the required opioid dosage together with concomitant adverse effects. The purpose of this study is to identify the types of available evidence on opioid adjunct therapy in pain management, to clarify key concepts and definitions in the literature, and to examine how research is conducted on this topic. This project follows an interpretative scoping review methodology. From January to August 2019, systematic literary and web-based key word searches were conducted. PubMed, Cochrane Library, Google Scholar, and Scopus databases were searched using major search terms such as "Opioids", "Adjunctive therapy", and "Pain management". The review identified 118 published studies in 9 categories of research study design. Randomized control trials made up 66% of the research reports. Additional designs include systematic reviews, meta-analyses, narrative reviews, and observational studies such as case reports, case series, cross-sectional, case-control, and cohort studies. By identifying key studies and classes of drugs, this review addresses whether there is sufficient evidence available for clinicians to answer key questions on adjunct drugs in opioid pain management.