Pulmonary Hypertension - Ambrisentan

Hello - my husband has just started Ambrisentan for his Pulmonary Hypertension. I'd like to hear if others are taking and side effects? After 3 days of taking, his breathing is worse and it was very bad before. Terrible. He also has Polycytothenia Rubra Vera & is in his first month taking Besremi (interferon) which knocked his platelet count down amazingly fast. Perhaps the breathing worsening could be tied to that but it happened really after the Ambrisentan. Thank you for sharing.