Nasal route delivery system evaluation

Formulation and dosage form aspects that can impact the site of deposition within the nasal cavity are a key consideration for nasal delivery. The site of deposition can impact absorption due to the differences in the permeability and residence time of the anterior and posterior portions of the nose. A variety of dosage forms such as nasal drops, sprays, gels, powders, or microspheres are available for administering pharmaceuticals by the nasal route, and these options need to be carefully evaluated because the type of dosage form can impact where the formulation is deposited in the nasal cavity and, in turn, the systemic absorption. For example, the bioavailability of nasally administered desmopressin was significantly increased in a spray formulation compared with drops, " likely... 

Other routes of administration have been evaluated, such as inhalation, intrale-sional, intranasal, intraperitoneal, intraventricular, and intraocular rates, in clinical studies. For the most part, these alternative routes were attempts to improve the delivery of interferon to sites not easily accessible via the systemic circulation. These dosing strategies have provided adequate concentrations of interferon in cerebrospinal fluid, lymph, nasal mucosa, and peritoneal fluid, but have not led to clinical success, undoubtedly reflecting the lack of understanding of the inherent mechanism of interferon action [164]. 

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