17044
Despite these advantages , the development of allosteric ligands is often difficult from a medicinal chemistry standpoint due to the more complex challenge of identifying allosteric leads and their often flat or confusing SAR .
 None
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