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Naltrexone , a nonselective opioid receptors antagonist , totally blocked compound 31 antinociceptive effects on the hot plate test , but naltrindole ( delta opioid antagonist ) and nor - binaltorphimine ( kappa opioid antagonist ) did not .
 Chemical: Naltrexone; Chemical: naltrindole; Chemical: nor - binaltorphimine
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: naltrindole; Chemical: nor - binaltorphimine