Cardiac drug and psychotropic drug interactions: significance and recommendations.

Understanding cardiac drug interactions with concurrent psychotropic prescriptions is essential for the practicing cardiologist, primary care physician, and psychiatrist. There has been an explosion in the use of new drugs in both psychiatry and cardiology without widespread knowledge of their potential interactions. The increasing tendency toward polypharmacy, the use of psychotropic medications by cardiologists and primary care physicians caring for cardiac patients, and the growth of the aging population present major challenges for the practitioner. Finally, there is a need to have models and paradigms for predicting potential drug interactions-the cytochrome P450 schema. This article describes a method to identify, understand, and codify the interactions between psychotropic and cardiac drugs, a systematic approach for updating this key database, and specific cardiac-psychotropic drug interactions. Specifically, this paper 1) details the interactions, 2) addresses the level of their clinical significance, 3) describes the potential mechanism(s) of the interactions, and 4) offers recommendations to the clinician (Appendix). Because the majority of the original clinical trials, either for cardiac medications or for psychotropic drugs, did not include studies comparing these two drug domains contemporaneously, their interactions often become known only with their combined use in the clinical arena, using the patient as "guinea pig" and through subsequent reporting.