uk-dgm MCQ (SBA): Doxazosin-Induced Postural Hypotension in Heart Failure

A 77-year-old man with chronic heart failure is reviewed. He reports dizziness on standing and has had one fall in the past month. His medications include Ramipril 10 mg, Bisoprolol 10 mg, Furosemide 80 mg, Spironolactone 25 mg, and Doxazosin 4 mg (added by a different GP for nocturia attributed to BPH). His lying BP is 132/78 and standing BP is 98/56. Which medication is MOST likely contributing to his symptoms?