Background: In the early stages of the 2009 influenza pandemic, little was known about the pandemic (H1N1) 2009 virus or its response to neuraminidase inhibitor therapy.
Methods: Between April 2009 and August 2010, we conducted an open-label study of the response to oseltamivir therapy when administered at the recommended dose or at double the recommended dose twice daily for 5 days.
Results: Thirty-eight patients aged 5 years or older with laboratory-confirmed pandemic (H1N1) 2009 influenza were randomly assigned to treatment. After 5 days, substantial reductions in viral load and clinical signs and symptoms of influenza were observed in the standard- and double-dose groups relative to baseline values. The double-dose regimen did not provide additional benefit over the standard-dose regimen. No resistant viruses were detected. Both regimens were well tolerated, and no serious adverse events were reported.
Conclusions: Standard- and double-dose oseltamivir regimens were well tolerated in this patient group.
From the *Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo; †Hospital Universitário, Universidade de São Paulo, São Paulo; ‡Centro Médico São Francisco, Curitiba; and §Núcleo de Pesquisas em Geriatria Clínica e Prevenção, UNIFESP, São Paulo, Brazil.
Correspondence to: Edison L. Durigon, PhD, Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. prof. Lineu Prestes, 1374, São Paulo, SP CEP 05508-900, Brazil. E-mail: firstname.lastname@example.org.
Conflicts of interest and source of funding: E.D., L.T., D.O., P.M., and J.L. are employees or former employees of Universidade de São Paulo, which received funding from Roche for the conduct of study NCT00949533. E.D. received support from Roche for travel to the XII International Symposium on Respiratory Viral Infections, Taipei, Taiwan (March 11–14, 2010).
This work was supported by F. Hoffmann-La Roche Ltd.