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To determine if the addition of a buffering solution to adjust the pH of lidocaine into the physiologic range would reduce pain during injection , we performed a blinded randomized study in patients undergoing cardiac catheterization .
 lidocaine, pain
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 lidocaine, pain