▁could ▁be ▁used ▁to ▁improve ▁the ▁efficiency ▁of ▁eye ▁dro ps ▁and ▁provide ▁better ▁ret ention ▁on ▁oc ular ▁surfaces . ▁ ▁Rout es ▁of ▁Administration ▁ ▁O rom uc os al ▁With ▁a ▁ 0 . 1 - 0 . 7   mm ▁thick ▁m uc us ▁layer , ▁the ▁or al ▁cav ity ▁serves ▁as ▁an ▁important ▁route ▁of ▁administration ▁for ▁mu co ad hes ive ▁dos ages . ▁P erme ation ▁sites ▁can ▁be ▁separated ▁into ▁two ▁groups : ▁sub ling ual ▁and ▁bu cc al , ▁in ▁which ▁the ▁former ▁is ▁much ▁more ▁per me able ▁than ▁the ▁latter . ▁However , ▁the ▁sub ling ual ▁m uc osa ▁also ▁produces ▁more ▁sal iva , ▁resulting ▁in ▁relatively ▁low ▁ret ention ▁rates . ▁Thus , ▁sub ling ual ▁m uc osa ▁is ▁prefer able ▁for ▁rapid ▁on set ▁and ▁short ▁duration ▁treat ments , ▁while ▁the ▁bu cc al ▁m uc osa ▁is ▁more ▁appropriate ▁for ▁longer ▁dos age ▁and ▁on set ▁times . ▁Because ▁of ▁this ▁dich ot omy , ▁the ▁or al ▁cav ity ▁is ▁suitable ▁for ▁both ▁local ▁and ▁system ic ▁administration . ▁Some ▁common ▁dos age ▁forms ▁for ▁the ▁or al ▁cav ity ▁include ▁g els , ▁o int ments , ▁patch es , ▁and ▁table ts . ▁Depending ▁on ▁the ▁dos age ▁form , ▁some ▁drug ▁loss ▁can ▁occur ▁due ▁to ▁sw allow ing ▁of ▁sal iva . ▁This ▁can ▁be ▁minim ized ▁by ▁layer ing ▁the ▁side ▁of ▁the ▁dos age ▁facing ▁the