Potentially clinically relevant pharmacodynamic interactions between antiepileptic drugs and psychotropic drugs: An update

Background: Prior articles paid little attention to pharmacodynamic drug interactions (DIs) between antiepileptic drugs (AEDs) and the most important psychotropic medications (antidepressants, antipsychotics, benzodiazepines and lithium) which have potential to be clinically relevant. Objective: This article aims to provide an updated review of the potentially clinically relevant pharmacodynamic DIs between AEDs and psychotropic medications. Pharmacodynamic DIs take place directly at the site of action of a drug or indirectly by interfering with another physiological mechanism. From the clinical perspective, these DIs are classified as having 1) beneficial effects (increased efficacy and/or safety) or 2) harmful effects (de-creased efficacy and/or safety). Method: Articles, including animal studies, were obtained from a PubMed search with no time limit. This search went beyond the articles previously found and listed in the authors’ published literature reviews and DI studies. Results: Using knowledge of pharmacodynamic mechanisms, the potentially beneficial and dangerous pharmacodynamic DIs between AEDs and psychotropic drugs with psychotropic medications are summarized for clinicians in practical tables. The possible pharmacodynamic DIs of AEDs include 20 with antidepressants, 17 with antipsychotics, 4 with benzodiazepines and 5 with lithium. Conclusion: The pharmacodynamic DIs between AEDs and psychotropic drugs have not been systematically investigated or even described in the literature. Clinicians need to become more aware of the potential for dangerous combinations of the increasingly frequent co-prescription of AEDs and psychotropic agents. Likewise, researchers need to consider these DIs in their studies, and clinicians facing cases with adverse drug reactions secondary to these pharmacodynamic DIs need to publish them.