Descriptive study of drug-drug interactions attributed to prescriptions written upon discharge from the emergency department

Objective: The primary purpose of this study was to identify the most common drug-drug interactions (DDI'S) in patients prescribed medications upon discharge from the emergency department. Methods: We conducted a respective chart review of patients discharged home with a prescription from an academic emergency department. The study period was from August 1, 2015 to August 31, 2015. Patients will be excluded if they meet the following criteria: age under 20 years; discharge home without a prescription; inpatient hospital admission; transfer to another inpatient facility; or sign out against medical advice. The primary endpoint is the identification and characterization of drug-drug interactions caused by discharge prescriptions written by the treating physician. Results: A total of 500 patient charts were included, with 38% having at least one DDI. Overall, there were 429 DDIs among 858 prescriptions written. 15.6% (n = 67) of the DDI's were classified as B, no modification of therapy needed. 60% (n = 260) of the DDIs were risk-rating category C, requiring monitoring of therapy. 22% (n = 95) of the DDI's identified were category D, which are consider modification of therapy. Lastly, we identified 1.6% (n = 7) category X DDI's. The top 3 most commonly associated drugs were oxycodone/acetaminophen, ibuprofen, and ciprofloxacin. Conclusion: DDIs are occurring upon discharge from a large, urban, tertiary care, academic medical center. Many of the DDI's identified do not require any modification to therapy. However, 23.6% of identified DDI's required modification or were contraindicated. A majority of the category X drug interactions involved QT prolongation.