2754
Microinjection of fentanyl ( 2 . 5 micrograms / 50 nl ) directly into this pontine nucleus , on the other hand , elicited discernible electromyographic excitation .
 Chemical: fentanyl
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: fentanyl