MS-1749

A 70-year-old man visits his doctor for his yearly hypertension check-up. He is presently on the highest possible dose of ramipril, amlodipine, and indapamide. During the check-up, his blood pressure is recorded as 156/95 mmHg. The doctor advises him on lifestyle changes and suggests doxazosin. Can you explain the mechanism of action of this medication?