Objectives Since the outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the pressure to minimise its impact on public health has led to the implementation of different therapeutic strategies, the efficacy of which for the treatment of coronavirus disease 2019 (COVID-19) was unknown at the time. Remdesivir (REM) was granted its first conditional marketing authorisation in the EU in June 2020. The European Medicines Agency (EMA) and local health authorities all across the EU have since strongly recommended the implementation of pharmacovigilance activities aimed at further evaluating the safety of this new drug. The objective of this study was to evaluate adverse drug reactions (ADRs) attributed to either REM or hydroxychloroquine (HCQ) in patients hospitalised for COVID-19 in Centro Hospitalar de Lisboa Ocidental, a Portuguese hospital centre based in Lisbon. We present the preliminary results reporting plausible adverse effects of either HCQ or REM.

Methods An observational cohort study was carried out between 16 March and 15 August 2020. Participants were divided into two cohorts: those prescribed an HCQ regimen, and those prescribed REM. Suspected ADRs were identified using an active monitoring model and reported to the Portuguese Pharmacovigilance System through its online notification tool. The ADR cumulative incidence was compared between the two cohorts.

Results The study included 149 patients, of whom 101 were treated with HCQ and the remaining 48 with REM. The baseline characteristics were similar between the two cohorts. A total of 102 ADRs were identified during the study period, with a greater incidence in the HCQ cohort compared with the REM cohort (47.5% vs 12.5%; p<0.001). Causality was assessed in 81 ADRs, all of which were considered possible.

Conclusions Real-world data are crucial to further establish the safety profile for REM. HCQ is no longer recommended for the treatment of COVID-19.