Safety of fexofenadine and other second-generation oral antihistamines before and after the removal of the prescription requirement in Italy and other European countries: A real-world evidence study and systematic review

Background: The change from prescription to over-the-counter (OTC) status of oral antihistamines may raise concerns about drug safety due to the possibility of misuse/abuse. In most European countries, oral antihistamines are available without prescription, whereas in Italy, only <10-tablet packs are available OTC. Objectives: To evaluate the safety profile of fexofenadine after OTC switch in Italy in a real-world setting, and to compare its safety profile to that of other European countries where larger pack sizes are available. To compare the safety of fexofenadine, cetirizine, and loratadine in Italy. To examine safety/efficacy across Europe with a systematic review. Methods: This case-by-case analysis used the US Food and Drug Administration (FDA) adverse event reporting system (FAERS) to extract data of the adverse events (AEs) related to fexofenadine, loratadine and cetirizine in Italy January 2010-June 2020. The year 2016 was taken as the index date (removal of prescription requirement) for evaluation of the reporting trend of AEs of fexofenadine in Italy and make a comparison pre/post-OTC switch. A comparison of AEs with other European countries where fexofenadine is sold OTC in large packs >20 tablets (Belgium, Portugal, Switzerland, Finland, Hungary) was made. The rate at which an AE related to oral antihistamines occurred was estimated by calculation of the reporting rate (number of cases/[defined daily dose/1000 inhabitants per day]) on the basis of IQVIA sales data using the Italian Institute of Statistics database. A systematic review of the literature was also performed. Results: There were 3760 reports of AEs with a suspected association with fexofenadine; of these, eight were reported from Italy. There was a slightly increasing trend per year, in line with a general reporting trend of other drugs. In European countries where fexofenadine is available, the impact of OTC switch on AE reporting activity was negligible: from 2016, the reporting rate increased slightly and then normalized at 3.01, an incidence value similar to that recorded before the OTC switch (3.7 in 2015). Of 22 studies included in the systematic review, 18 (82%) positively evaluated the OTC use of oral antihistamines, confirming an acceptable safety/tolerability profile. Conclusion: There was no difference in number of AEs reported for fexofenadine pre/post-OTC switch, indicating a similar safety profile. Spontaneous reporting systems are a valuable source of real-world data and support the OTC provision of oral antihistamines in Europe and fexofenadine in Italy, in addition to supporting the use of larger pack sizes in Italy.