Objective: It is important to prevent dispensing errors for the safety of patients.  For this purpose, it is necessary to improve the dispensing process on the basis of risk priority.  Quantitative evaluation of risk in each operation makes it possible to compare the risk relatively.  In this study, we analyzed data reported in the Pharmacy Risk Error Management System (PREM-S) to evaluate the risk priority in the medicine preparation step of the dispensing process.
Methods: Data of 1,202 cases concerning medicine preparation step were extracted from in 2,458 cases reported into PREM-S between May 2010 and April 2011.  We classified the medicine preparation step into 31 categories based on the operation.  We analyzed the levels in each category as adverse effects on patient’s health by the errors and also the relationship between adverse effect and detection time.  The level represents the degree of adverse effect for the patient.
Results: Information on levels of the 31 categories was obtained from the analysis.  Eight categories included reports of effects on the health of patients.  Three categories such as calculation of powder medicine included level 4 cases.  Detection time was significantly different between level 1 and levels 2 to 4, but there was no significant difference between levels 2 to 4.
Conclusion: The results suggest that analysis of data reported in PREM-S enables evaluation of the risk priority systematically and efficiently.  Evaluation of the risk priority will contribute to prevention of dispensing errors and health effects derived from them.