2908
Prazosin exerts its antihypertensive effects through vasodilatation caused by selective blockade of postsynaptic alpha - 1 adrenergic receptors .
 Chemical: Prazosin
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
 Entities: Prazosin 
Answer:
 Chemical: Prazosin