A composition is described having improved oral permeability of polar agents such as neuraminidase inhibitors. The composition includes one or more polar agents and one or more permeability enhancers such that the composition increases the amount of the polar agent capable of being transported across a Caco-2 cell membrane by at least 150% relative to the amount capable of being transported across the Caco-2 Cell membrane in the absence of the permeability enhancer. Oral dosage forms including the composition, and methods of treating or preventing influenza infection are also provided.本發明描述一種組成物,其包括具有改良之經口滲透性的極性劑(諸如神經胺酸酶抑制劑)。所述組成物包括一或多種極性劑以及一或多種滲透性增強劑,以使得組成物將能夠穿過Caco-2細胞膜運送之極性劑的量相對於在不存在滲透性增強劑之情況下能夠穿過Caco-2細胞膜運送之量增加至少150%。本發明亦提供包括所述組成物之口服劑型,以及治療或預防流行性感冒感染之方法。