OBJECTIVES: All subjects of drug circulation inform the regulator about serious adverse reactions, lack of effect, reactions due to abuse or overdose. The effectiveness of the spontaneous reporting method within the framework of post-registration pharmacovigilance is determined by the quality of information provided by the applicants.

METHODS: Based on the data obtained during the registration of spontaneous reports in the national automatized information system of pharmacovigilance in the Russian Federation for the period from 28.04.2020 to 10.12.2020.

RESULTS: Seventy reports were included in the analytical phase. For most adverse reactions, the severity criterion "clinically significant event" was applied.For hydroxychloroquine, serious unanticipated adverse reactions included: "feeling sick"; "tongue pain"; "hair loss"; "seminal fluid incontinence"; "death"; "blood in stool"; "pulmonary embolism".

CONCLUSIONS: In accordance with international pharmacovigilance requirements, the reports submitted to the system cannot be considered valid due to the lack of date of disease onset, nosological group of the disease, date of prescription/rejection of the suspected medication. It is not possible to correctly assess the causal link between the event and the use of hydroxychloroquine. According to the analysis of reference documents (Prescribing information, Summary of Product Characteristics, Risk Management Plan, literature sources) the most important identified risks of hydroxychloroquine are cardiotoxicity, myelotoxicity, gastro-toxicity, neuromuscular conduction disorders, musculoskeletal and sensory system disorders, hepatotoxicity, skin disorders. Activation of tuberculosis and reactivation of chronic viral hepatitis B are the most important potential risks.