2957
Intraperitoneal ketanserin administration at doses of 0 . 63 and 2 . 5 mg / kg prevented the alfentanil - induced increase in electromyographic activity compared with animals pretreated with saline .
 Chemical: ketanserin; Chemical: alfentanil
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: ketanserin; Chemical: alfentanil