26620
To our knowledge , the unique type of prodrugs like 2 , 28 , and 31 was not reported in the past and could represent a novel prodrug approach for secondary amides , a class of molecules frequently identified as drug candidates .
 Chemical: secondary amides
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: secondary amides