A Study of Intravenous Oseltamivir [Tamiflu] in Infants With Influenza

• Steady-state pharmacokinetics parameters AUC0-12 and Cmax of oseltamivir and oseltamivir carboxylate [ Time Frame: Multiple sampling day 3 or 4 ] [ Designated as safety issue: No ]
• Safety Profile: AEs, vital signs, laboratory parameters [ Time Frame: Days 1-11 and on follow up days 15 and 30 ] [ Designated as safety issue: No ]

• Viral load and shedding [ Time Frame: Assessment days 1, 3 or 4, 6, 11, and optional at days 15 and 30 ] [ Designated as safety issue: No ]
• Development of resistance to oseltamivir [ Time Frame: Assessment days 1, 3 or 4, 6, 11, and at days 15 and 30 if samples are collected ] [ Designated as safety issue: No ]

This open-label study will assess the pharmacokinetics and safety of oseltamivir [Tamiflu] in 3 cohorts of infants, aged 0-30 days, 31-90 days and 91-<365 days with influenza infection. Patients will receive 10 doses of intravenous oseltamivir [Tamiflu] therapy over 5 or 6 days. Optional oral therapy with oseltamivir [Tamiflu] may be considered following the intravenous dose associated with pharmacokinetic blood sampling. Evidence of continued virus shedding at day 6 can allow for up to 5 additional days (10 doses) of oral or intravenous administration. Anticipated time on study drug is 5-11 days. Target sample size is <50 patients.

Inclusion Criteria:

• Infant patients
• Date of birth to date of enrollment is <1 year
• Diagnosis of influenza
• Duration of influenza symptoms </=96 hours prior to first dose
• - Parent/guardian willing to have patient receive intravenous therapy for 3 or 4 days (5 or 6 doses of study drug)

Exclusion Criteria:

• Date of conception to date of birth + date of birth to enrollment is <36 weeks
• Creatinine clearance <30 mL/min/1.73m2
• Patients receiving any form of renal replacement therapy at baseline
• Clinical evidence of severe hepatic decompensation at the time of enrollment
• Patients taking probenecid medication within 1 week prior to study day 1 or during the study