Intrapulmonary Pharmacokinetics of Laninamivir, a Neuraminidase Inhibitor, after a Single Nebulized Administration of Laninamivir Octanoate in Healthy Japanese Subjects [PublishAheadOfPrint]

A single inhaled dose of laninamivir octanoate (LO) using a dry powder inhaler (DPI) is effective for the treatment and prophylaxis of influenza. Nebulizers are an option for pediatric and elderly patients who may have difficulty in using a DPI. A single-center, open-label study was conducted to evaluate the plasma and intrapulmonary pharmacokinetics (PK) of laninamivir after a single nebulized administration of LO in healthy male Japanese subjects for identifying a safe and effective dosage regimen for a nebulizer. A single dose of LO (40–320 mg) was administered using a nebulizer and plasma concentrations of LO and laninamivir were analyzed up to 168 h after inhalation by validated liquid chromatography-tandem mass spectrometry methods. Subgroups of 6 subjects each underwent bronchoalveolar lavage at specified time intervals over 4–168 h following a single nebulized administration of LO (160 mg) and the concentrations in epithelial lining fluid (ELF) were calculated by the urea diffusion method. PK parameters were determined by non-compartment analysis. Inhaled nebulized LO was found to be safe and well-tolerated up to the highest dose evaluated (320 mg). Plasma laninamivir concentrations increased almost dose-proportionally. Laninamivir concentrations in ELF exceeded the 50% inhibitory concentrations for viral neuraminidase up to 168 h after the nebulized inhalation of 160 mg LO. Thus, similar to the DPI, ELF concentration profiles of laninamivir after a single nebulized administration supports its long lasting effect against influenza virus infection.

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