ColumnsDrug-Drug Interactions (DDIs) in Psychiatric Practice, Part 6: Pharmacodynamic ConsiderationsPRESKORN, SHELDON H. MDAuthor Information PRESKORN: Kansas University School of Medicine-Wichita, Wichita, KS This column has been adapted with permission from Appendix 4 in Preskorn SH. Drug-Drug Interactions With an Emphasis on Psychiatric Medications, First Edition. West Islip, NY and Durant, OK: Professional Communications; 2018. To order a copy of the book, readers can call 1-800-337-9838 or visit the Professional Communications website at www.pcibooks.com. Over his 40-year career, S.H.P. has worked with over 140 pharmaceutical and biotech companies in the United States and throughout the world. Over the past year, he has received grants/research support from or has served as a consultant, on the advisory board, or on the speaker’s bureau for Alkermes, Allergan, Bionomics, BioXcel, Janssen, National Institute of Mental Health, Perception Neuroscience, and Sunovion. All clinical trial and study contracts were with and payments made to the Kansas University Medical Center Research Institute, a research institute affiliated with Kansas University School of Medicine-Wichita. Please send correspondence to: Sheldon H. Preskorn, MD, University of Kansas Medical Center, 1010 N. Kansas, Wichita, KS 67217. Journal of Psychiatric Practice: July 2019 - Volume 25 - Issue 4 - p 290-297 doi: 10.1097/PRA.0000000000000399 Buy Metrics Abstract This column is the sixth in a series exploring drug-drug interactions (DDIs) with a special emphasis on psychiatric medications. The first 3 columns in this DDI series discussed why patients being treated with psychiatric medications are at increased risk for taking multiple medications and thus experiencing DDIs, how to recognize such DDIs, strategies for avoiding and/or minimizing adverse outcomes from such DDIs, and pharmacokinetic considerations concerning DDIs in psychiatric practice. The fourth and fifth columns in this series presented a pair of parallel tables, one of which outlined the primary, known mechanism(s) of action of all commonly used psychiatric medications and one of which summarized major types of pharmacodynamic DDIs based on mechanism of action. Clinicians can use these 2 tables together to predict pharmacodynamically mediated DDIs. This sixth column in the series discusses some key issues related to pharmacodynamic interactions involving commonly used psychiatric medications. The column first discusses 3 types of pharmacological agents that deserve special mention because of the widespread types of pharmacodynamic DDIs they can have with psychiatric and other medications: ethanol, opioids, and monoamine oxidase inhibitors, with a special focus on hypertensive crises and serotonin syndrome with monoamine oxidase inhibitors. The column also discusses DDIs in terms of effects on the cardiovascular system, including QTc prolongation, blood pressure and heart rate regulation, increased risk of bleeding and abnormal bleeding, and valvular heart disease, and on the central nervous system, including increased sedation, respiratory depression, body temperature regulation, and tardive dyskinesia. The overall goal of this series of columns is to present a simple way of conceptualizing neuropsychiatric medications in terms of their pharmacodynamics and pharmacokinetics to allow prescribers to take these facts into consideration when they need to use more than 1 drug in combination to optimally treat a patient. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.