8173
In this study , oxycodone - based and hydrocodone - based haptens were conjugated to KLH to generate immunogens that would recognize both oxycodone and hydrocodone .
 Chemical: oxycodone; Chemical: hydrocodone; Chemical: oxycodone; Chemical: hydrocodone
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: oxycodone; Chemical: hydrocodone; Chemical: oxycodone; Chemical: hydrocodone