Nasal bioavailability formulation factors

Describe the formulation factors that may affect nasal bioavailability. 

Suspensions may also be used to deliver nasal formulations, though only rarely, since a number of complicating factors (e.g., particle size and morphology) must be considered. Suspensions offer the advantage of increasing residence time in the nasal cavity, thus possibly augmenting nasal bioavailability. 

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