Incidence, type and causes of dispensing errors: a review of the literature

To identify, review and evaluate the published literature on the incidence, type and causes of dispensing errors in community and hospital pharmacy.

Electronic databases were searched from 1966 to February 2008. This was supplemented by hand-searching the bibliographies of retrieved articles. Analysis of the findings explored the research methods, operational definitions, incidence, type and causes of dispensing errors.

Sixty papers were identified investigating dispensing errors in the UK, US, Australia, Spain and Brazil. In general, the incidence of dispensing errors varied depending on the study setting, dispensing system, research method and operational definitions. The most common dispensing errors identified by community and hospital pharmacies were dispensing the wrong drug, strength, form or quantity, or labelling medication with the incorrect directions. Factors subjectively reported as contributing to dispensing errors were look-alike, sound-alike drugs, low staffing and computer software. High workload, interruptions, distractions and inadequate lighting were objectively shown to increase the occurrence of dispensing errors.

Comparison of the reviewed studies was confounded by differences in study setting, research method and operational definitions for dispensing errors, error rate and classification of error types. The World Health Organization is currently developing global patient safety taxonomy. Such a standardized taxonomy for dispensing errors would facilitate consistent data collection and assist the development of error-reduction strategies.