Clinically significant drug-drug interactions between oral anticancer agents and nonanticancer agents: Profiling and comparison of two drug compendia

BACKGROUND: Use of oral anticancer agents is gaining wide acceptance in the treatment of cancer. However, patients receiving oral therapy are at high risk for drug-drug interactions (DDIs). OBJECTIVE: TO create a drug profile for each clinically significant DDI involving selected oral anticancer agents and evaluate the agreement between 2 commonly used DDI compendia: Drug Interaction Facts (DIF) 2008 and Micromedex DRUGDEX. METHODS: DDI profiles were developed based on primary and tertiary literature reviews. DIF 2008 and Micromedex DRUGDEX were compared to assess the consistency of listings, severity, and scientific evidence ratings of DDIs involving the oral anticancer agents that were selected. The Spearman correlation test was used to assess the correlation of the severity ratings between the 2 compendia. RESULTS: A total of 184 DDIs were identified. A DDI profile was created for 40 of these that met the predetermined criteria for clinically significant interactions. The comparative assessment showed inconsistency in DDI listings (15.2% of those identified were listed in DIF only and 46.7% were listed in Micromedex only), severity ratings (Spearman correlation coefficient 0.49), and scientific evidence ratings (disagreement 25.8%). CONCLUSIONS: The discrepancies in DDI listing and rating systems between the compendia evaluated here reflect the need for more studies to standardize the definitions and classifications of DDIs.