Developing RxNorm Extension: A Step Toward Global Drug Data Harmonization in Observational Drug Research

This paper presents RxNorm Extension (RxE), a standardized drug vocabulary system designed to harmonize drug data across international databases. RxE integrates drugs from multiple national drug repositories, enhancing global drug safety and effectiveness research by standardizing drug representations in disparate drug vocabularies to a structure following RxNorm, a reference standard in the US. We developed an attribute-based mapping approach that improves consistency and reduce manual data processing. Based on 12 vocabularies included, we observe similar dose form and ingredient usage patterns but many more brand names available worldwide. The quality of RxE depends on the thorough examination of the source vocabulary, where challenges include discrepancies in brand names, poorly structured dosage forms, and faulty dosages. Despite the challenges, RxE has been used in numerous clinical and methodological studies. Future directions focus on expanding coverage, improving mapping automation, and fostering international collaboration to optimize global drug safety and effectiveness efforts.