Mucoadhesive

Mucoadhesive refers to a material or formulation capable of adhering to mucosal surfaces, such as the lining of the mouth, nose, eye, vagina, or gastrointestinal tract. Mucoadhesive systems are designed to resist mucociliary clearance and mechanical forces, thereby extending the residence time of a dosage form and enhancing local or systemic drug delivery.

Adhesion results from interactions between the mucoadhesive polymer and mucus, including polymer swelling, interpenetration of polymer chains with mucin, electrostatic attraction, hydrogen bonding, van der Waals forces, and, in some cases, covalent bonding with mucin or epithelial surfaces. Hydration of the polymer forms a gel that can anchor to the mucus layer.

Materials used include natural polymers such as chitosan, alginate, gelatin, and cellulose derivatives; and synthetic polymers such as poly(acrylic acid) derivatives (carbomers), polycarbophil, and hydroxypropyl cellulose. Thiolated polymers (thiomers) form disulfide bonds with mucus, increasing adhesive strength. Formulations include tablets, films, gels, patches, and nanoparticles intended for buccal, nasal, vaginal, ocular, or oral administration.

Evaluation uses ex vivo mucosa tests, texture analysis, and wash-off methods to measure detachment force and residence time. In vivo studies help link mucoadhesion to drug bioavailability. Applications span multiple mucosal routes, with advantages in sustained release and targeted delivery but challenges from mucus variability, mucociliary clearance, and potential irritation.

Mucoadhesive design emphasizes safety, biocompatibility, and stability under physiological conditions, with regulatory emphasis on adhesion characterization, rheology, and mucosal toxicity.