24661
This study describes the structure - activity relationship for carefully characterized N - alkyl - N - quaternary chitosan derivatives as permeation enhancers for drugs that are mainly absorbed through the paracellular pathway , such as macromolecular drugs and hydrophilic drugs , in a well defined bronchial epithelial cell line .
 Chemical: N - alkyl; Chemical: N
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: N - alkyl; Chemical: N