11233
Thus , the three lower doses had no effect , but at the dose of 5 . 15 mu mol / kg / day theophylline suddenly increased the stepping to 56 +/- 5 % of the maximal effect observed when the treatment of these same rats was switched to an equimolar dose of caffeine .
 Chemical: theophylline; Chemical: caffeine
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: theophylline; Chemical: caffeine