Multidrug Interactions: Why Do They Occur and How to Handle?

A nonoptimized medication therapy (NOMT) event is an iatrogenic hazard or incident associated with medications and is a leading cause of death, serious injury, and illness. NOMT events are often related to multidrug interactions in patients with polypharmacy. In these patients, NOMT events can be avoided by using advanced clinical decision support systems and clinical interventions such as separating the time of administration of certain drugs during the day. At the individual level, medication reconciliation is a first logical step for reducing adverse side effects. Then, intersubject variability in drug response should be considered to optimize patient drug regimens. Furthermore, patient pharmacogenomic status information can help ensure appropriateness of drug therapy. However, in patients with polypharmacy, such information is most valuable when combined with phenoconversion probability. At a population level, the virtual addition of drugs to various drug regimens and the use of a medication risk score can help predict the risk of NOMT events. This review outlines some of the mechanisms behind multidrug interactions and their association with drug safety and NOMTs, polypharmacy and its impact on patient outcomes, the value of pharmacogenomics, and an assessment of simulation studies and the virtual addition of drugs to a drug regimen using real-world data.