Background The frequency of medication errors and their causes has been analysed in a number of studies with the aim of defining quality strategies that guarantee the patient’s safety. The dispensing process is a key factor in preventing errors of this kind, and our aim was to further explore the errors that occur during this process, by carrying out a qualitative and quantitative analysis of the reasons for complaints in our hospital.

Purpose To study the reasons why complaints are received in relation to medicines in the unit dose system, so we could implement corrective measures that improve the dispensing process.

Materials and methods Prospective descriptive observational study.

Over a 5-month period (from June to October 20102, on 30 randomly-selected days), the standard medicine complaint forms were analysed.

The statistical analysis was carried out using the Stata12^® program.

Results The percentage of medicines for which complaints were received in relation to the total medicines dispensed during this period was 0.93%.

The mean for the daily complaints was 51.77 (CI 95% 46.44–57.09).

In the qualitative and quantitative analysis of the reasons for complaints, we obtained the following percentages (CI 95%):

• Medicine marked as dispensed, but requested from the ward: 43.21%(40.76–45.68).

• Incorrect method of administration: 27.04%(2.01–3.34).

• Prescription form not received by pharmacy: 14.62%(12.95–16.46).

• Pharmaceutical transcription error to computerised dispensing programme: 11.91%(10.39–13.62).

• Pending distribution: 6.18%(5.09–7.49).

• Medicine prescribed ‘if necessary’ (stock on ward used): 5.15%(4.16–6.37).

• Error in nurses’ record book: 3.54%(2.73–4.58).

• Not sent because stock on ward used: 1.61%(1.09–2.37).

• Broken, dropped on floor: 1.09%(0.68–1.75).

• Other reasons: 9.98%(8.59–11.57).

Conclusions Analysing the reasons for complaints allows pharmacy services to identify the areas in the system where a higher number of errors occur, making it possible to suggest corrective measures and evaluate actions taken to improve the system.

No conflict of interest.