Background and importance The unit dose system of medication distribution (UDDS) is a pharmacy-coordinated method of dispensing and controlling medications in healthcare settings. In our hospital, medications contained in single-unit packages are delivered for each patient by doses (sorted by administration time) for a 24-hour period.

Aim and objectives To detect and analyse errors in the cart-fill process in a UDSS by doses.

Material and methods A prospective observational study was conducted during the month of April 2021. The errors found in the cart-fill process in a UDSS by doses were assessed. Medication was daily prepared by doses for each patient for a 24-hour period, according to physicians’ prescriptions. Patients were randomly selected and their medication, prepared and double-checked by the pharmacy staff, was reviewed by a pharmacist.

The following variables were collected: number of patients, prescription lines, units of medicines and detected errors. Errors were classified into four possible categories: incorrect dose (over or under), incorrect unit of medicine (excess, default or absence), medicine not prescribed, and incorrect administration time.

Results Medication of 500 patients was reviewed. A total of 4232 prescription lines and 6000 units of medicines were assessed. Only 5 errors were detected, which represents an error rate of 0.083%.

The errors detected were the following: 1 of incorrect dose by overdose (0.016%), 1 of incorrect unit of medicine by excess (0.016%), 1 of incorrect unit of medicine by default (0.016%) and 2 of incorrect administration time (0.033%).

Conclusion and relevance The review of the medication carts before their arrival at the Clinical Units allows the detection of potential medication errors in their preparation that may affect the safety of the patient. The percentage of error obtained indicates the degree of quality related to the medication dispensing system. In this case, the error rate is low, although it could be lower in the case of automation of the process instead of manual preparation.

Conflict of interest No conflict of interest