Abstract. The 2009 pandemic influenza A(H1N1) infection in Malaysia was first reported in May 2009 and oseltamivir was advocated for confirmed cases in postexposure prophylaxis. However, there are cases of oseltamivir-resistance reported among H1N1-positive patients in other countries. Resistance is due to substitution of histidine by tyrosine at residue 275 (H275Y) of neuraminidase (NA). In th...

UNLABELLED Oseltamivir phosphate is extensively metabolized in the ex vivo human placenta model, and the transplacental passage of the metabolite oseltamivir carboxylate is incomplete. OBJECTIVE To evaluate the metabolism and transplacental transfer of oseltamivir (Tamiflu) in the ex vivo human placental model. STUDY DESIGN Perfusion studies were performed in six placentas from term, uncomp...

Oseltamivir is contraindicated for people aged 10-19 in principle in Japan, due to concern about abnormal behaviours. Sudden death is another concern. This review examines growing evidence of their association and discusses underlying mechanisms of these sudden-onset type reactions to oseltamivir. First, the importance of animal models and the concept of human equivalent dose (HED) is summarize...

UNLABELLED Influenza B viruses with a novel I221L substitution in neuraminidase (NA) conferring high-level resistance to oseltamivir were isolated from an immunocompromised patient after prolonged oseltamivir treatment. METHODS Enzymatic characterization of the NAs (Km, Ki) and the in vitro fitness of viruses carrying wild-type or mutated (I221L) NA genes were evaluated. Proportions of wild-t...

The worldwide prevalence of H3N2 influenza virus and its increasing resistance to the existing drugs necessitates for the development of an improved/better targeting anti-influenza drug. H3N2 influenza neuraminidase is one of the two membrane-bound proteins belonging to group-2 neuraminidases. It acts as key player involved in viral pathogenicity and hence, is an important target of anti-influe...

CD8(+) T cells directed against conserved viral regions elicit broad immunity against distinct influenza viruses, promote rapid virus elimination and enhanced host recovery. The influenza neuraminidase inhibitor, oseltamivir, is prescribed for therapy and prophylaxis, although it remains unclear how the drug impacts disease severity and establishment of effector and memory CD8(+) T cell immunit...

The prevalence and timing of emergence of oseltamivir-resistant seasonal and pandemic influenza A (H1N1) viruses in Myanmar in 2008 and 2009 are described in this report. In 2008, the oseltamivir-resistant seasonal H1N1 virus was detected at a lower rate (6%) and emerged at least 2 months later when compared with neighboring countries. Similarly, the prevalence of pandemic H1N1 virus was low (3...

BACKGROUND Data on the clinical effectiveness of oseltamivir in patients with pandemic 2009 influenza A(H1N1) (A[H1N1]) virus infection are scarce. We aimed to determine the effect of timing of oseltamivir administration on outcomes in hospitalized adults with A(H1N1). METHODS Observational analysis of a prospective cohort of adults hospitalized with laboratory-confirmed A(H1N1) was performed...

BACKGROUND The Taiwan CDC provided free oseltamivir to all patients with influenza infections confirmed by rapid testing or who had clinical warning symptoms during the 2009 H1N1 influenza pandemic in Taiwan. However, oseltamivir utilization patterns, cost, and outcomes among oseltamivir-treated patients remained unclear. METHOD A population-level, observational cohort study was conducted usi...

A 2008 review by our group concluded that the risk of neuropsychiatric adverse events (NPAEs) in influenza patients was not increased by oseltamivir exposure, and did not identify any mechanism by which oseltamivir or its metabolites could cause or worsen such events. The current article reviews new information on this topic. Between September 16, 2007 and May 15, 2010, 1,805 spontaneously-repo...