BACKGROUND Resistance of pandemic A(H1N1)2009 (H1N1pdm09) virus to neuraminidase inhibitors (NAIs) has remained limited. A new mutation I223R in the neuraminidase (NA) of H1N1pdm09 virus has been reported along with H275Y in immunocompromised patients. The aim of this study was to determine the impact of I223R on oseltamivir and zanamivir susceptibility. METHODS The NA enzymatic characteristi...

The H275Y oseltamivir resistance mutation confers high-level resistance to oseltamivir in isolates of human A(H1N1) influenza. We report the recovery and identification of an influenza B virus with the H273Y neuraminidase point mutation directly from a human patient. The H273Y influenza B isolate is resistant to oseltamivir and peramivir but sensitive to zanamivir.

An outbreak of oseltamivir-resistant influenza A (H1N1) occurred in a long-term care facility. Eight (47%) of 17 and 1 (6%) of 16 residents in 2 wards had oseltamivir-resistant influenza A virus (H1N1) infections. Initial outbreak response included treatment and prophylaxis with oseltamivir. The outbreak abated, likely because of infection control measures.

BACKGROUND In Spring 2009, a novel reassortant strain of H1N1 influenza A emerged as a lineage distinct from seasonal H1N1. On June 11, the World Heath Organization declared a pandemic - the first since 1968. There are currently two main branches of H1N1 circulating in humans, a seasonal branch and a pandemic branch. The primary treatment method for pandemic and seasonal H1N1 is the antiviral d...

Oseltamivir is a potent inhibitor of influenza virus neuraminidase enzymes essential for viral replication. This study aimed to investigate the impact of covariates on pharmacokinetic (PK) variability of oseltamivir and its active metabolite form, oseltamivir carboxylate (OC). Dosing history, plasma drug concentrations, and demographic information were pooled from 13 clinical trials providing d...

BACKGROUND Dose selection is an important step in pharmacokinetic (PK) studies of hemodialysis patients. We propose a simulation-based dose-selection method for PK studies of hemodialysis patients using a subpharmacological dose of oseltamivir as a model drug. METHODS The concentrations of oseltamivir and its active metabolite, oseltamivir carboxylate (OC), were measured by liquid chromatogra...

BACKGROUND Oseltamivir has been used as a drug of choice for the prophylaxis and treatment of human influenza A(H1N1)pdm09 infection across the world. However, the most frequently identified oseltamivir resistant virus, influenza A(H1N1)pdm09, exhibit the H275Y substitution in NA gene. OBJECTIVES This study aimed to determine the prevalence and phylogenetic relationships of oseltamivir resist...

tamivir-resistant A (H1N1) infections that were treated with oseltamivir reported a shorter duration of cough; however, no other differences were found. We also compared the proportion of patients who reported fever, cough, sore throat, chills, myalgia or arthralgia, and difficulty breathing. Patients with oseltamivir-resistant A (H1N1) infection that was treated with oseltamivir were less like...

BACKGROUND Oseltamivir resistance in A(H1N1)pdm09 influenza is rare, particularly in untreated community cases. Sustained community transmission has not previously been reported. METHODS Influenza specimens from the Asia-Pacific region were collected through sentinel surveillance, hospital, and general practitioner networks. Clinical and epidemiological information was collected on patients i...

AIM To investigate whether oseltamivir enhances the anticoagulant effect of warfarin and to evaluate any pharmacokinetic (PK) interaction between the agents. METHODS Twenty volunteers (mean age 62 years) receiving daily warfarin and with INR values of 2.0-3.5 during the previous 2 weeks were randomized to concomitant oseltamivir 75 mg twice daily for 4.5 days or warfarin alone in a two-way cr...