Background and Importance Drug compounding errors can result in patient harm. Hence, the importance of reviewing formulations to ensure their quality and safety.

Aim and Objectives To analyse the risk derived from our current process of sterile and non-sterile compounding, through error records registered for 1 year, and to list and prioritise measures to solve them.

Material and Methods A descriptive study, including errors related to sterile and non-sterile compounding (non-parenteral nutrition, non-chemotherapy) registered from October 2022 to September 2023, was conducted. Errors were classified according to their causes. Error’s severity was determined subjectively by the pharmaceutical team.

A brainstorming session was organised, with technicians and the pharmacist leading safety, to discuss the critical points of the entire process. An Ishikawa diagram was created to visually capture the critical points. Improvement measures to reduce risk of errors were listed and prioritised by feasibility and effectiveness.

Our current process consists of: – Organisation: Outlook schedule, email requests, electronic and paper prescriptions – Non-sterile compounding: managed through Magisfor® software – Sterile compounding: managed through processing forms.

Results Sixty-four errors were detected: seven (10.9%) due to organisational causes, six (9.4%) derived from software/processing forms, eight (12.5%) compounding process, five (7.8%) quality control, five (7.8%) packaging, 23 (35.9%) labelling, seven (10.9%) storage, and three (4.7%) due to validation causes.

Twenty-five (39%) errors were considered severe. Errors were mainly detected by pharmacists during the validation process (n=54, 84%), others by technicians/nurses.

In total, 25 main critical points were detected through the Ishikawa diagram.

Improvement measures that could be implemented are:

• Outpatient scheduling

• Training in our actual software, good clinical practice and the compounding process

• Evaluate other programmes that include sterile compounding

• Periodic revision of the processing forms

• Strategic placement or marking active ingredients/excipients susceptible to cause confusion

• More microbiological controls

• Periodic revalidation of technicians

• Reduce technician turnover and less multitasking

• Measures we could prioritise would be those related to technicians training and revalidation.

Conclusion and Relevance Several critical points were detected in our process of sterile and non-sterile compounding. We found some measures that could help us to reduce risk of errors, but we think that we should prioritise those related to technicians training and revalidation.

Conflict of Interest No conflict of interest.