21837
Similarly , BTX - A - induced pain reduction was abolished by low dose of intrathecal naltrexone and by selective mu - antagonist naloxonazine .
 Chemical: naltrexone; Chemical: naloxonazine
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: naltrexone; Chemical: naloxonazine