19784
The approved treatments for Alzheimer ' s disease ( AD ) exploit mainly a symptomatic approach based on the use of cholinesterase inhibitors or N - methyl - d - aspartate ( NMDA ) receptor antagonists .
 Chemical: N - methyl - d - aspartate; Chemical: NMDA
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: N - methyl - d - aspartate; Chemical: NMDA