19187
Older age [ 75 + vs . < 75 years ; hazards ratio ( HR ) 1 . 16 , 95 % confidence interval ( CI ) 1 . 06 - 1 . 27 ] and drug type ( rivastigmine vs . donepezil ; HR 1 . 15 , 95 % CI 1 . 03 - 1 . 27 ) increased the risk of non - persistence .
 rivastigmine, donepezil
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 rivastigmine, donepezil