Mucoadhesion: a review of characterization techniques.

IMPORTANCE OF THE FIELD: Mucoadhesive drug delivery vehicles attract much attention owing to benefits such as extended residence time of the drug at the site of application, a relatively rapid uptake of a drug into the systemic circulation, and enhanced bioavailability of therapeutic agents. Mucoadhesion, defined as the ability to adhere to the mucus gel layer covering organs that are exposed to the outer surface of the body yet are not covered with skin, such as the mouth and the respiratory tract, is a key element in the design of these drug delivery systems. AREAS COVERED IN THIS REVIEW: This review focuses on the numerous experimental methods that have been proposed over the years for mucoadhesion characterization. These techniques are categorized into directs methods, which measure the force or time required to detach the mocoadhesive from a mucus, and indirect methods, which asses the interactions between the mucoadhesive and mucin type glycoproteins. WHAT THE READER WILL GAIN: The comprehensive description of the available techniques could facilitate the selection of a characterization method that meets the requirements of a specific study. Moreover, a comparison between the results obtained in different laboratories is given whenever possible. TAKE HOME MESSAGE: The challenge of adopting a universal test method that could be used to compare data from different research groups and rank new mucoadhesion candidates has not yet been met.