18317
Despite the disappointing results of these antagonists in the field of heart failure , almost from the initial animal trials of bosentan , a dual endothelin receptor antagonist , in pulmonary arterial hypertension , it has been demonstrated that the drug leads at least to hemodynamic and clinical improvement of the patients , thus receiving official approval for the management of this rare but eventually lethal disease .
 Chemical: bosentan
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: bosentan