“The results provided objective data to inform my decision to taper fluoxetine therapy and increase their lamotrigine dose to help stabilize the patient as fluoxetine concentrations decreased and also as amitriptyline levels were likely decreasing with the resolved CYP 2D6 inhibition.”

Leveraging High-Complexity Toxicology Testing to Assess Adherence and Identify Drug-Drug Interactions in Psychiatric Care

Drug-drug interactions (DDIs) have been a long-standing contributor to adverse drug events (ADEs) and are capable of impacting medication efficacy and toxicity. For Louisiana-based psychiatric physician assistant, Halie Ory, PA-C, CAQ-Psych, having results of Aegis’s InterACT Rx drug interaction test helped to identify a potential DDI that could reduce the efficacy of a medication prescribed for one of her patients and also potentially lead to supratherapeutic levels of another medication. Additionally, the patient had not reported this interacting medication to Ms. Ory, so she was unaware the patient was taking it.

The patient was being treated for major depressive disorder and generalized anxiety disorder. The patient was prescribed fluoxetine and amitriptyline by their primary care provider. They were referred to Ms. Ory’s practice for further management due to complaints of worsening depression and anxiety. As part of her plan for ongoing assessment of medication adherence, Ms. Ory utilized a definitive urine toxicology analysis for medication adherence monitoring and with that also ordered InterACT Rx testing. “Before making additional changes to the medication therapy, I determined it was medically necessary to order medication adherence testing through Aegis and also include the InterACT Rx testing due to the patient’s poor response to medication therapy and complex past medical history,” Ms. Ory explained. The results revealed severe DDIs between fluoxetine and amitriptyline, and fluoxetine and clopidogrel.

The results provided objective data to inform my decision to taper fluoxetine therapy and increase their lamotrigine dose to help stabilize the patient as fluoxetine concentrations decreased and also as amitriptyline levels were likely decreasing with the resolved CYP 2D6 inhibition.

The results provided objective data to inform my decision to taper fluoxetine therapy and increase their lamotrigine dose to help stabilize the patient as fluoxetine concentrations decreased and also as amitriptyline levels were likely decreasing with the resolved CYP 2D6 inhibition.

Halie Ory, Psychiatric Physician Assistant
Resource Management Services provides behavioral health services to meet the individual needs of children, adolescents, and adults who face challenges related to emotional, behavioral, or mental health issues.