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4 . The majority of the drug was excreted in urine as multiple open ring metabolites : M17 . 3 ( oxidative ring - opened product ) and M22 . 2 ( di - cysteine conjugate of 17 . 3 ) ; unchanged PTZ601 in urine contributed to 15 % of radioactivity .
 Chemical: di - cysteine; Chemical: PTZ601
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: di - cysteine; Chemical: PTZ601