▁or al ▁cav ity ▁with ▁an ▁imper me able ▁co ating ( , ) ▁commonly ▁seen ▁in ▁patch es . ▁ ▁Nas al ▁ ▁With ▁an ▁active ▁surface ▁area ▁of ▁ 1 6 0   cm 2 , ▁the ▁nas al ▁cav ity ▁is ▁another ▁not ew orth y ▁route ▁of ▁mu co ad hes ive ▁administration . ▁Due ▁to ▁the ▁swe eping ▁motion ▁of ▁the ▁c ilia ▁that ▁lines ▁the ▁m uc osa , ▁nas al ▁m uc us ▁has ▁a ▁quick ▁turn over ▁of ▁ 1 0 ▁to ▁ 1 5 ▁minutes . ▁Because ▁of ▁this , ▁the ▁nas al ▁cav ity ▁is ▁most ▁suitable ▁for ▁rapid , ▁local ▁medic inal ▁dos ages . ▁Additionally , ▁its ▁close ▁proxim ity ▁to ▁the ▁blood - bra in ▁bar rier ▁makes ▁it ▁a ▁convenient ▁route ▁for ▁admin ister ing ▁special ized ▁dru gs ▁to ▁the ▁central ▁nerv ous ▁system . ▁G els , ▁solutions , ▁and ▁a eros ols ▁are ▁common ▁dos age ▁forms ▁in ▁the ▁nas al ▁cav ity . ▁However , ▁recent ▁research ▁into ▁particles ▁and ▁mic ros pher es ▁have ▁shown ▁increased ▁bio av ail ability ▁over ▁non - sol id ▁forms ▁of ▁medicine ▁largely ▁due ▁to ▁the ▁use ▁of ▁mu co ad hes ives . ▁ ▁O cular ▁ ▁Within ▁the ▁eye , ▁it ▁is ▁difficult ▁to ▁achieve ▁th era pe ut ic ▁concentr ations ▁through ▁system ic ▁administration . ▁O ften , ▁other ▁parts ▁of ▁the ▁body ▁will ▁reach ▁to xic ▁levels ▁of ▁the ▁medic ation ▁before ▁the