ABSORPTION ENHANCERS IN NASAL DRUG DELIVERY - EFFICACY AND SAFETY

Efficacy and safety of nasal absorption enhancers depend on many diffe rent parameters, such as their influence on nasal epithelial membrane barriers, the enzymatic activities in the nasal cavity, and the mucoci liary clearance. Large interspecies differences appear to exist in the nasal absorption of drugs. Nasal absorption enhancers, although very effective in some cases, differ substantially in efficacy and safety. For a number of enhancers like surfactants, bile salts and fusidate de rivatives a good relationship (similarity in rank order) can be establ ished between the morphological damage and the influence on the ciliar y beat frequency (CBF) of nasal epithelial tissue, making CBF measurem ents a valuable tool in the search for safe nasal absorption enhancers .