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2 . The objective of this article is to examine the effects of single and repeated administrations of silymarin on pharmacokinetics of a P - gp substrate , risperidone , and its major metabolite , 9 - hydroxyrisperidone , in rats .
 Chemical: risperidone; Chemical: 9 - hydroxyrisperidone
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: risperidone; Chemical: 9 - hydroxyrisperidone