[Comprehensive Analysis of Compounded Prescription Orders: Types of Errors and Variability Among Autonomous Communities in Spain].

Introduction: Compounding (FM) is a drug prepared according to the specific needs of a patient, under medical prescription, when the marketed medicines are not adequate according to the patient's pathology. This is why the FM is the last link in the Health System, in which the prescription is one of the critical elements of the FM preparation process. This study analyzes the distribution of FM, the most frequent errors and if there is any relation between the format used and the errors detected or where has it been prescribed.

Methodology: Human compounding prescriptions which were obtained from a third party manufacturing pharmacy from the 1st of September until the 30th of November of 2023. All mandatory data from RD 1718/2010 of 17th of December was collected, as well as the specialty of the drug, where has been prescribed and what the format used is. On these prescriptions, a descriptive analysis will be carried out as well as an analysis of the absence of legally mandatory data.

Results: a total of 6694 compounding prescriptions have been obtained, being the most frequent the ones from Madrid (4050), Castilla la Mancha (CLM) (1132) and Castilla y Léon (CyL) (1047) as the most common places of prescription.The most common format is paper (56,3 %), in which a lesser incidence of errors is observed in this format (5,9 (σ=2,889 SE=0,047)) rather than in electronic format (9,52 (σ=2,151 SE= 0,04)). On the other hand, significant difference were found among the number of errors per prescription and Autonomous Community (CCAA) (ANOVA p>0,001) and the number of errors per prescription and the format used (ANOVA p>0,001).

Discussion: The largest number of prescriptions come from Madrid, CLM and CyL, with a notable frequency of ophthalmology and dermatology prescriptions. The most commonly used format is paper in the public and private spheres, with the exception of the Madrid Health System, where electronic formats predominate. It is noteworthy that electronic formats have a much higher error rate than paper formats, posing a potential risk for the preparation of the prescription.

Conclusion: The results of frequency distribution by medical specialty may not be extrapolated due to overestimation of sterile pharmaceutical forms; however, format used and errors can be extrapolated.Despite what might be expected, electronic prescriptions are not the most commonly used format, possibly because they present a higher rate of errors per prescription. This higher rate can be caused by an incomplete prescription, deficient communication between the prescription system and the program used in pharmacies to access to this prescription or not knowing how to access the prescription data.