11425
At substrate concentrations ( 0 . 25 - 2 micro M ) approximating plasma concentrations occurring clinically , rates of methadone enantiomer N - demethylation by CYP2B6 . 6 , incubated individually or as the racemate , were one - third to one - fourth those by CYP2B6 . 1 .
 Chemical: methadone; 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: methadone; Chemical: N