4187
During TH , morphine elimination half - life ( t ( 1 / 2 ) ) was significantly higher , while total clearance ( CL ( tot ) ) was significantly lower ( median [ semi - interquartile range ( s - iqr ) ] ) : t ( 1 / 2 ) , 266 ( 43 ) versus 168 ( 11 ) minutes , P < 0 . 01 ; CL ( tot ) , 1201 ( 283 ) versus 1687 ( 200 ) ml / min , P < 0 . 01 .
 morphine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 morphine