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To characterize the nature , time course and dose dependency of zidovudine - related side effects , we undertook a multicenter , prospective , dose - range finding study .
 Chemical: zidovudine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: zidovudine