2784
Twenty patients were asked to quantify the severity of pain after receiving standard lidocaine in one femoral area and buffered lidocaine in the opposite femoral area .
 pain, lidocaine, lidocaine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 pain, lidocaine, lidocaine