Drug interactions and polypharmacy

Abstract

Over the past 20 years the number of psychotropic medications has increased dramatically. As a result, the use of psychotropic polypharmacy has rapidly expanded. One outcome of psychotropic polypharmacy has been an increase in the number of drug interactions that occur in routine clinical practice. Although drug interactions resulting in death are rare, the effects of drug interactions are often misinterpreted as drug inefficacy or toxicity. Therefore an understanding of pharmacodynamic and pharmacokinetic drug interactions is essential when using polypharmacy. This chapter reviews the mechanisms of drug interactions, describes the most commonly seen drug interactions and offers suggestions for addressing drug interactions in clinical practice. Given polypharmacy is common in psychiatry; clinicians must routinely assess which medication combinations are safe to prescribe, require dose adjustments and are best avoided. Future research should focus on the role of genetics and interventions to decrease adverse drug reactions related to drug interactions.