Oral dosing is generally considered to be the most patient-friendly and convenient way to administer medication. However, there are incidents where a pharmaceutical cannot be administered orally due to inadequate oral bioavailability, which may limit the usefulness of a compound. As a result, utilizing a permeation enhancer may be a better way to administer medication. Absorption enhancers are excipients included in formulations to improve the absorption of an active pharmaceutical ingredient (API). Absorption enhancers usually refer to an agent whose function is to increase absorption by enhancing membrane permeation, rather than increasing solubility, so such agents are sometimes more specifically termed permeation enhancers.