22120
RATIONALE : Naltrexone , a non - selective opioid antagonist , decreases the euphoria and positive subjective responses to alcohol in heavy drinkers .
 Chemical: Naltrexone; Chemical: alcohol
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: alcohol