How many hospital pharmacy medication dispensing errors go undetected?

This study directly observed more than 140,000 medication doses filled at a tertiary academic medical center, reporting an error rate of 3.6%. Of the undetected errors observed, nearly a quarter represented potential adverse drug events (ADEs) with incorrect medications, strength, and dosage form being the most common. The authors provide a detailed account of the classification and types of dispensing errors with a discussion of contributing factors.