6896
Addition of a 6 - aryl - 4 , 5 - dihydropyridazin - 3 ( 2H ) - one extension to the N - alkyl group facilitates both enhancement of PDE4 - inhibitory activity and restoration of potent PDE3 inhibition .
 Chemical: 6 - aryl - 4 , 5 - dihydropyridazin - 3 ( 2H ) - one; Chemical: N
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: 6 - aryl - 4 , 5 - dihydropyridazin - 3 ( 2H ) - one; Chemical: N