19839
In this study , the relationship between CSF - to - unbound plasma drug partitioning in rats and the mouse Pgp ( Mdr1a ) efflux ratio ( ER ) obtained from in vitro transcellular studies has been investigated for a set of 61 CNS compounds exhibiting substantial diversity in chemical structure and physico - chemical properties .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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