Enzymatic degradation nasal epithelium

The thin, porous and highly vascularised nasal epithelium has a high total blood flow, which facilitates fast absorption of substances. Direct transport to the systemic circulation or the central nervous system makes it possible to obtain a rapid therapeutic effect. The intranasal absorption depends on the mucociliary clearance, pathological conditions such as infections, allergy and obstruction, mucus secretion, moisture content, enzymatic degradation, and blood flow. It should be remembered that the blood flow can be affected by either locally or systemically active substances. These phenomena can determine the nasal absorption of substances. Oxymetazoline and clonidine reduce the blood flow, while phenylephrine and salbutamol raise it. 

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