Polydrug Use

This chapter reviews selected research topics and issues in relation to research on polydrug use. It includes a review of the history of the concept of polydrug use and often-referenced terminological confusion in this area of public health research. A pharmacoepidemiological perspective on responses to drug compounds taken in combination is presented, with coverage of sometimes misunderstood concepts such as interaction, antagonism, and synergy. The distinction is made between a description of subgroup variation in responses to a drug and drug–drug interactions for which there is an underlying pharmacological or toxicological theory to guide the research. Finally, there is a selective review of published evidence on population studies of polydrug use, with an emphasis upon investigations with epidemiologically defined populations under study. This review is organized in relation to five main rubrics of epidemiology, and includes topics, issues, and directions for future research on patterns of polydrug use.