Polypharmacy in Bipolar Disorder - a Focus on Drug - Drug Interactions

Background: Drug-drug interactions (DDI) are actually quite commonplace and are responsible for considerable patient morbidity and mortality. The two major varieties of DDI are pharmacodynamic and pharmacokinetic interactions (cytochrome P450 system). Conditions such as bipolar disorder (with many psychiatric and somatic comorbidities) are complex symptom clusters and bipolar patients may need different medications for different phases of their illness. Objective: The objective of the study is evaluation of drugdrug interactions in treatment of bipolar disorder with/ without psychiatric and somatic comorbidities. Method: Retrospective review study of the psychiatric charts of randomly taken 100 inpatients with bipolar disorder (according to DSM IV TR), with/ without psychiatric and somatic comorbidities, admitted to Obregia Hospital over the last two years. First we collected data about patients age, gender, principal diagnosis, psychiatric and somatic comorbidities, psychiatric and somatic medications, smoking, coffee and alcohol use. Then, we reevaluated patient’s treatment received in hospital and collected data about oral contraceptives, antibiotics and symptomatic drugs use. We analyzed statistically these data and assessed the DDI. Results: The results had shown that the vast majority of subjects had psychiatric and somatic comorbidities. And by that, this increased the risk of polypharmacy and druggrug interactions via cytochrome P450. Drug interactions of vignettes are common situations. All interactions cannot provide but if possible, should be avoided for complicated therapeutic schemes. Conclusions: Not seeing is not equivalent of not occurring. The more psychiatric drugs a patient is taking, the risk for injurious DDIs and cumulative toxicity is greater.