18803
Similarly , ( R ) - omeprazole HI in hmEMs , htEMs , and PMs were 5 . 6 , 3 . 1 , and 0 . 3 , respectively , which were significantly different , but no significant difference was present in the ( S ) - omeprazole HI .
 ( R ) - omeprazole, ( S ) - omeprazole
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ( R ) - omeprazole, ( S ) - omeprazole