Mapping Compounding Medication Errors and Contributing Factors in Hospital Pharmacy: A Scoping Review.

Medication errors in hospital pharmacy compounding pose a significant patient safety risk due to complex workflows, high-risk products, and system-level vulnerabilities encompassing human, technological, and organizational factors. Compounding errors may lead to clinically significant patient harm, including treatment failure, toxicity, prolonged hospitalization, irreversible morbidity, and death. Understanding incident types and their contributing factors is essential for designing targeted safety interventions. Accordingly, this scoping review aimed to map incidents reported in the literature, including medication errors and near misses, and to identify contributing factors associated with the medicine compounding process in hospital pharmacy. A systematic scoping review was conducted following the Joanna Briggs Institute and PRISMA-ScR guidelines and was previously registered on the Open Science Framework. Searches in PubMed, Scopus, and Web of Science were performed without date restrictions. Titles, abstracts, and full texts were screened independently by 2 reviewers, with disagreements resolved through discussion or by including a third reviewer. Data extraction used a standardized template to capture incident and drug type, pharmaceutical form, compounding stage, and contributing factors, and to categorize them according to international patient safety frameworks. From the 763 identified articles, 58 were included. Errors most frequently involved incorrect formulation, incorrect drug or ingredient selection, and dose or concentration deviations. Incidents were concentrated in early and intermediate stages of the compounding process, particularly prescription validation, formulation, and preparation. Staff-related issues, including attention, fatigue, and emotional factors, as well as work environment and organizational factors, were the most frequently reported. In conclusion, compounding errors mainly arise from vulnerabilities in key stages of the compounding process and from interacting staff-related, environmental, and organizational factors. Systematic screening of compounded errors and their contributing factors highlights the need for continuous improvement, thereby strengthening patient safety in hospital pharmacy practice.