4000
In an attempt to determine whether penile pain associated with intracorporeal injections could be due to the acidity of the medication , we performed a randomized study comparing the incidence of penile pain following intracorporeal injections with or without the addition of sodium bicarbonate to the intracorporeal medications .
 penile pain, penile pain, sodium bicarbonate
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 penile pain, penile pain, sodium bicarbonate