Background and Importance Acenocoumarol is an anticoagulant derived from coumarin, which acts as a vitamin K antagonist. Its dosing regimen is adjusted according to the desired international normalised ratio (INR). Given its great inter and intraindividual variability, very disparate dosing is required, and the narrow therapeutic margin makes it a drug that is very susceptible to adverse drug events.

Aim and Objectives The aim of this study is to detect errors in the reconciliation of treatment with acenocoumarol in patients admitted to the emergency department.

Material and Methods Descriptive, observational, retrospective study, which included all patients over 18 years of age, treated with acenocoumarol, admitted to the hospital in April 2022. The primary endpoint was the incidence of acenocoumarol prescribing errors in the emergency department. The weekly dose prescribed in hospital and the weekly outpatient dose were compared. The following variables were also obtained: sex, age, medical observations on acenocoumarol prescription, pharmacy treatment reconciliation report, and whether the regimen was adjusted during hospitalisation. A descriptive statistical analysis was performed using measures of central tendency such as median and mean, using the SPSS v.23® program.

Results 31 patients treated with acenocoumarol were included who were admitted to the emergency department in April 2022. Sixty-one percent were men and the median age was 80 ± 12years (RIQ, 72–85). Prescribing errors were found in 58% (18) of patients, with a higher than expected dose in 19%. Of these patients, the prescriber recorded a note in 61% of patients and the pharmacy service requested treatment reconciliation in 56%. Among the 18 patients with prescribing errors, the regimen was corrected before hospitalisation in 6%, while in 56% the regimen was not adjusted during admission. In 1 patient an overdosage with acenocoumarol was observed, causing a serious adverse effect that required treatment.

Conclusion and Relevance In our study we observed a high percentage of prescription errors with acenocoumarol during hospital admission. This shows the need for treatment reconciliation in the emergency department. The erroneous regimen is maintained during hospital stay in 56% of patients, which can lead to serious medication errors. We conclude that the variable dosing of acenocoumarol requires greater attention on the part of health staff when reconciling treatment.

Conflict of Interest No conflict of interest