In patients where the nasal polyps do not seem to respond to the above protocol (or if patient is refusing surgery), the addition of a very strong drug called Zyflo (zileuton) may be of benefit. This drug can cause liver damage (in <10% of patients) and as such, liver function bloodwork (AST/ALT) is required every month for 3 months and yearly thereafter. As long as the AST/ALT numbers do not exceed 150 (yes, it is higher than what is considered normal), it is generally considered safe to continue with this drug (though would check bloodwork weekly if that happens to ensure stability). Getting an immunologist involved in the care of such patients would also be beneficial, especially for those patients where the nasal polyps are particularly resistant to standard treatment.
The major part of the approximately 150 cm 2 surface in the human nasal cavity is covered by respiratory epithelium, across which systemic drug absorption can be achieved. The olfactory epithelium is situated in the upper posterior part and covers approximately 10 cm 2 of the human nasal cavity. The nerve cells of the olfactory epithelium project into the olfactory bulb of the brain, which provides a direct connection between the brain and the external environment. The transfer of drugs to the brain from the blood circulation is normally hindered by the blood–brain barrier (BBB), which is virtually impermeable to passive diffusion of all but small, lipophilic substances. However, if drug substances can be transferred along the olfactory nerve cells, they can bypass the BBB and enter the brain directly.,