  RxNorm was utilized as the basis for direct-capture of medication history
data in a live EHR system deployed in a large, multi-state outpatient
behavioral healthcare provider in the United States serving over 75,000
distinct patients each year across 130 clinical locations. This tool
incorporated auto-complete search functionality for medications and proper
dosage identification assistance. The overarching goal was to understand if and
how standardized terminologies like RxNorm can be used to support practical
computing applications in live EHR systems. We describe the stages of
implementation, approaches used to adapt RxNorm's data structure for the
intended EHR application, and the challenges faced. We evaluate the
implementation using a four-factor framework addressing flexibility, speed,
data integrity, and medication coverage. RxNorm proved to be functional for the
intended application, given appropriate adaptations to address high-speed
input/output (I/O) requirements of a live EHR and the flexibility required for
data entry in multiple potential clinical scenarios. Future research around
search optimization for medication entry, user profiling, and linking RxNorm to
drug classification schemes holds great potential for improving the user
experience and utility of medication data in EHRs.
