Bostentan is a -

Ans. is 'b' i.e., Endothelin receptor antagonist Endothelin receptor antagonists o There are two endothelin receptor subtypes - ETA and and ETB. o Bosentan is a nonselective endothelin antagonist - blocks both ETA and ETB. o Bosentan is active intravenously and orally. o Bosentan is currently approved for use in pulmonary hypeension. Tezosentan another nonselective antagonist is used investigation for the treatment of acute hea failure. o Sitaxentan and ambrisentan are selective ETA antagonists. o Phosphoramidon inhibits formation of endothelin by inhibiting endothelin conveing enzyme. Remember o Bosentan can cause severe hepatotoxicity - monthly liver function tests should be done. o It is contraindicated in pregnancy.