A 58-year-old man with benign prostatic hyperplasia (BPH) presents with lower urinary tract symptoms (LUTS) including nocturia (×4/night), weak stream, and post-void residual urine of 80 mL. He is started on an alpha blocker. After 2 weeks of therapy, he reports dizziness on standing and a syncopal episode while getting out of bed in the morning. Blood pressure supine: 145/92 mmHg; standing: 110/68 mmHg. Which of the following alpha blockers would be the LEAST likely to cause this adverse effect?