23397
Among the various possible causes for drug interactions , pharmacokinetic factors such as inhibition of drug - metabolizing enzymes , especially cytochrome P450 ( CYP ) enzymes , are regarded as the most frequent and clinically important .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None