ABSTRACT
It is increasingly recognized that the mucus lining all mucosal surfaces in the body may comprise a barrier to drug delivery. Numerous approaches are currently applied to understand in more detail the chemical composition and corresponding physical states of the mucus barrier as well as how this barrier responds to drug molecules, other exogenous compounds, excipients, and drug delivery systems. In this chapter, we first provide an overview of the mucus as a barrier to drug delivery, and the current general knowledge on mucus composition and function in health and disease followed by a thorough outline of the most important strategies and approaches to overcome the mucus barrier for successful drug delivery. Current mucus models and in vitro, ex vivo, in situ, and in vivo methods applied to study diffusion in and interactions with mucus are highlighted and related to the overarching aim: understanding and overcoming the mucus barrier.
