Active metabolite from Tamiflu® solution is bioequivalent to that from capsule delivery in healthy volunteers: A cross-over, randomised, open-label study

The bioavailability of oseltamivir phosphate and oseltamivir carboxylate were assessed in healthy volunteers when delivered as a solution of the active pharmaceutical ingredient (API) compared with the commercial capsule formulation. The 90% confidence intervals (CIs) for the ratios of the two treatments (capsule versus solution) were within the reference region [0.80–1.25] for area under the curve (AUC0–infinity: [0.94–0.99]) and maximum observed plasma concentrations (Cmax: [0.93–1.08]). Thus, the two formulations were bioequivalent for oseltamivir carboxylate. For pandemic stockpiling of Tamiflu®, governments can therefore choose between the capsule formulation alone, the API alone, or quantities of both.