Nasal drug absorption factors influencing

Fig. 4 Variable factors influencing nasal drug absorption, and related key points for practical application.

The physicochemical properties of a molecule which affect its absorption across the nasal epithelium are broadly the same as those affecting transepithelial absorption at any site and have been discussed extensively in Section 1.3.4. These factors influence the mechanism and rate of drug absorption through the nasal epithelium. 

There are two major barriers in the mucosal absorption of peptide and protein—a penetration barrier and an enzymatic barrier (as supported by Lee ), which are relevant to nasal delivery. Taking those into consideration, basic factors influencing the nasal absorption of peptide and protein drugs will be discussed in this section. 

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