Medicine Shortages: An Algorithm for Evaluating the Substitution with Equivalent or Alternative Products

<b>Background/Objectives</b>: Drug shortages are a serious issue affecting health systems worldwide, determined by multiple causes including supply issues, regulatory limitations, and market distortions. The possible repercussions on patients may impair therapeutic efficacy. Despite numerous actions being implemented by regulatory authorities, including market monitoring, export restrictions, and temporary regulation mitigations, few instruments have been made available to help health operators find marketed alternatives to unavailable products. The aim of this work was to create an algorithm to find equivalent or alternative medicinal products available in a certain pharmaceutical market. Algorithm development and validation were performed using the medicinal products marketed in Italy. <b>Methods</b>: First, a newly assembled code, describing the active pharmaceutical ingredient by its Anatomical Therapeutical Chemical (ATC) code, and its dosage form by the European Directorate for the Quality of Medicines & HealthCare (EDQM) Standard Terms, was attributed to each marketed medicinal product. Then, the algorithm was set up to identify its possible equivalents or alternatives by assigning a score quantifying differences in Defined Daily Dose (DDD) per presentation unit and in characterizing Standard Terms. <b>Results</b>: The algorithm was validated on a randomized sample of medicinal products, proving to be able to identify appropriate equivalents or alternatives; moreover, it was tested in real conditions by submitting a survey to health professionals, who found this product to be reliable and useful. <b>Conclusions</b>: The developed algorithm may be employed as a rational tool to help health operators find solutions to drug shortages. This work highlighted some limits of the current ATC attribution that should be addressed by the competent authorities.