Drug transporters in the nasal epithelia and their contribution in drug delivery

[摘要] The nasal route has primarily been used to deliver drugs for the treatment of local diseases such as nasal infections, nasal congestion and allergies. The nasal route can also be used as a non-invasive alternative route to deliver drugs systemically when a rapid onset of action and/or avoidance of hepatic metabolism are desired. Moreover, there is a growing interest in the use of this route for direct transport of drugs from the nose to the brain. Most of the drugs that have been studied for nasal delivery are either small molecules which are lipophilic enough to passively diffuse through the nasal epithelia or macromolecules where bioavailabilities less than 1% are clinically effective and acceptable. This study focused on identifying carrier proteins or transporters in the nasal mucosa that could improve the absorption of specific drug substrates across the nasal respiratory and olfactory epithelia. The presence of drug transporters in the nasal mucosa of humans and commonly used animal models were investigated. DNA microarray results for nasal samples from humans and two commonly used models, mice and rats, were obtained from GenBank and were analyzed in collaboration with the University of Iowa Center for Bioinformatics and Computational Biology. While cow tissues are frequently used in in-vitro nasal permeability analyses, there is limited information available in GenBank for this species. Both DNA microarray analysis and RT-PCR were performed on bovine nasal explants to determine transporter expression. Good agreement between the microarray and RT-PCR results was observed. While human and three animal species commonly used as models in nasal drug delivery research (mouse, rat, and cow) show similar patterns of expression for several transporters, interspecies differences in the level of expression were observed. Therefore, the expression level of transporters remains a factor to consider when translating results obtained using animal models to humans. The nucleoside transporter family was selected for further evaluation of the potential to improve the nasal absorption of substrates. Nucleoside transporters are integral proteins responsible for mediating and facilitating the flux of nucleosides across cellular membranes; they are also known to be responsible for the uptake of nucleoside analog drugs such as anti-cancer and anti-viral agents. RT-PCR and Western blotting were used to verify the presence of two transporter subtypes, ENT1 and CNT3, in the bovine nasal respiratory and olfactory mucosa. The expression level of both transporters in the respiratory mucosa was comparable to that in the olfactory mucosa. Using

[发布机构] University of Iowa