It is very likely that during an influenza pandemic, intravenous zanamivir will be used in combination with oseltamivir. Although the potential for a drug interaction between the two drugs is very low, the likelihood of coadministration combined with the common route of renal clearance of both drugs and the current lack of information on the organic anion transporter polypeptides (OATP) inhibition potential of zanamivir in vivo warrants verification of a lack of an interaction. This study will provide clinical guidance for the use of intravenous zanamivir in settings where oral oseltamivir is commonly used, such as areas in which human cases of H5N1 have been reported.