4289
CBA / Ca male mice started on AZT 0 . 75 mg / ml H2O at 84 days of age and kept on it for 687 days when dosage reduced to 0 . 5 mg / ml H2O for a group , another group removed from AZT to see recovery , and third group remained on 0 . 75 mg .
 Chemical: AZT; Chemical: AZT
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: AZT; Chemical: AZT