Nasal mucosal surface and mucus layer

The nasal mucosal surface and mucus layer represent the primary physiological barrier of the upper respiratory tract, serving as the first line of defense against inhaled pathogens, allergens, and particulates. This system comprises a pseudostratified ciliated columnar epithelium overlaid by a complex, bilayered mucus film consisting of a low-viscosity sol layer and a high-viscosity gel layer. The mucus is primarily composed of water, electrolytes, and high-molecular-weight glycoproteins known as mucins, specifically MUC5AC and MUC5B, which provide its viscoelastic properties. Its biological function is maintained through mucociliary clearance, where coordinated ciliary beating moves trapped materials toward the pharynx for elimination. In drug development, this layer is viewed as a significant barrier that formulations must navigate to achieve therapeutic efficacy, often requiring the use of mucoadhesive polymers or penetration enhancers. Pathological changes, such as mucus hypersecretion or impaired ciliary activity, are key features of diseases like allergic rhinitis and chronic rhinosinusitis. Understanding the interaction between drugs and this mucosal environment is essential for optimizing intranasal delivery of both local and systemic therapies.

Other names

Nasal mucosaNasal mucusSchneiderian membraneNasal epithelial surfaceNasopharyngeal mucosa

Drugs interact with this environment through mucoadhesion to increase residence time, modulation of mucociliary clearance rates, or by penetrating the viscoelastic mucus barrier to reach underlying epithelial receptors or the systemic circulation via the highly vascularized lamina propria.