Use of Oseltamivir during Influenza A (H1N1) Pandemic: analysis of adverse reactions reported to the ANMAT National Pharmacovigilance System

Abstract

INTRODUCTION: Oseltamivir is an antiviral drug used for profhylaxis and treatment of influenza. Adverse effects are known through clinical trials and in large part by the experience gained after its use in the last outbreak of avian influenza in Asia. Among the most serious reactions are reported cases of anaphylaxis, cutaneous events and psychiatric symptoms such as hallucinations, delirium and suicidal behaviour. OBJECTIVE: in line with various international regulatory authorities, during July 2009, the ANMAT through Pharmacovigilance Department launched the National Pharmacovigilance Plan for antiviral drugs used for prophylaxis and treatment of the pandemic H1N1 influenza virus. The plan called for reporting any signs or symptoms, paying particular attention to the cutaneous, hepatic and neuropsychiatric symptoms. METHOD: we analyzed all reports received during June to November 2009. The data considered were: sex, age, notifier, therapeutic modality, severity, classification of main side effect and imputation assigned. RESULTS: 179 notifications were received, most associated with treatment modality. As can be seen worldwide, in Argentina, the great majority of reported adverse reactions involve the gastrointestinal system, being mostly mild and self-limiting. Given the variability and severity of psychiatric cases reported it is very important to pay close attention to these reports. Reported cases include the QTc interval prolongation, an event not previously described in the literature. CONCLUSIONS: it is essential to continue with proactive monitoring of this drug because of the limited current experience and the benefits / risks ratio of the safety profile of this drug.