Introduction

For drug delivery, oral intake is the most common and widely accepted procedure. However, many active pharmaceutical ingredients (API) for example large biomolecules like peptides, proteins  and recombinant therapeutic agents typically have a very poor bioavailability after oral administration. Reasons are for example low mucosal permeability for large and hydrophilic molecules, a narrow absorption window at particular regions of the gastrointestinal tract (GIT), lack of stability in the gastrointestinal environment resulting in a decomposition prior to its absorption and low dissolved concentration of active ingredient in gastrointestinal contents [1–3]. One strategy to overcome these problems is the usage of bioadhesive dosage forms. Bioadhesion is defined as the adhesion of synthetic or natural macromolecules like polymers to biological tissue. A special type of bioadhesion is mucoadhesion where the tissue is covered by mucus …

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