Effect of withdrawal of fusafungine from the market on prescribing of antibiotics and other alternative treatments in Germany: a pharmacovigilance impact study

Purpose: Knowledge on unintended consequences of product withdrawals is limited. Fusafungine, indicated for treatment of upper respiratory airways disease (URAD), was withdrawn in the EU on May 28, 2016. Given concerns about possible substitution with antibiotics, this study aimed to assess the impact of the withdrawal of fusafungine on prescribing of antibiotics and other treatments. Methods: The study was conducted using data from general practitioner (GP) and ear, nose and throat (ENT) practices in IMS® Disease Analyzer Germany. The quarterly prevalence of fusafungine prescribing was analysed for consultations involving the most common URAD between May 29, 2013 and May 28, 2017 in regular fusafungine-prescribing practices. Trends in the quarterly prevalence of antibiotics (AB), other nasal or throat preparations (N&T) and tyrothricin were analyzed. Practices with no fusafungine prescribing during the study served as controls. Changes in prescribing trend were evaluated using interrupted time series regression analysis. Results: In fusafungine-prescribing practices, withdrawal of fusafungine was associated with an immediate increase in prescribing of other N&Ts among patients consulting for URAD (+ 6.4%, 95% CI 2.3–10.5% in GP practices and + 9.0%, 95% CI 5.5–12.5% in ENT practices). There was no increase in antibiotic prescribing. In ENT practices; a small transient increase in tyrothricin prescribing occurred. No changes were seen in non-fusafungine-prescribing practices. Conclusions: Withdrawal of fusafungine was not associated with increased prescribing of antibiotics but was associated with increased prescribing of other N&Ts. The unintended impact of substitution to other treatments should be considered routinely when products are withdrawn or restricted in other ways.