21517
As we have previously observed for OZ439 versus OZ277 , the OZ439 series peroxides had superior exposure and efficacy in mice compared to the corresponding OZ277 series peroxides .
 OZ439, OZ277, OZ439, peroxides, OZ277, peroxides
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 OZ439, OZ277, OZ439, peroxides, OZ277, peroxides