4504
After gastric - outlet obstruction was recognized in several infants who received prostaglandin E1 , we studied the association between the drug and this complication .
 gastric - outlet obstruction, prostaglandin E1
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 gastric - outlet obstruction, prostaglandin E1