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However , recent clinical studies have shown that a single low - dose injection of ketamine , an N - methyl d - aspartate receptor ( NMDAR ) antagonist , has rapid antidepressant effects that are observed within hours and are long lasting .
 Chemical: ketamine; Chemical: N - methyl d - aspartate
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: ketamine; Chemical: N - methyl d - aspartate