A 68-year-old man with benign prostatic hyperplasia presents with lower urinary tract symptoms including nocturia, hesitancy, and weak urinary stream. Digital rectal examination reveals a smooth, enlarged prostate. Post-void residual is 80 mL. He has no contraindications to medical therapy. What is the drug of choice for first-line treatment?

Explanation

## First-Line Medical Management of BPH **Key Point:** Alpha-1 adrenergic antagonists (α1-blockers) are the first-line pharmacological agents for symptomatic BPH with lower urinary tract symptoms (LUTS) in the absence of significant obstruction or post-void residual requiring intervention. ### Mechanism of Action Alpha-1 blockers (e.g., tamsulosin, doxazosin, alfuzosin) relax smooth muscle in the prostatic urethra and bladder neck, improving urinary flow and reducing obstructive symptoms. Tamsulosin is uroselective for α1A receptors in the prostate, minimizing systemic cardiovascular side effects. ### Why Tamsulosin is Preferred | Feature | Tamsulosin | Doxazosin | Finasteride | Tadalafil | |---------|-----------|----------|-------------|----------| | **Onset of action** | 2–3 weeks | 2–3 weeks | 6–12 months | 2–4 weeks | | **Symptom relief** | Rapid | Rapid | Slow (volume-dependent) | Moderate | | **Uroselective** | Yes (α1A) | No (non-selective) | N/A | N/A | | **Hypotension risk** | Low | Moderate–high | None | Moderate | | **First-line status** | Yes | Alternative | For large glands | Alternative | **High-Yield:** Tamsulosin is uroselective and causes fewer systemic side effects (orthostatic hypotension, dizziness) compared to non-selective α1-blockers like doxazosin. This makes it the preferred initial agent in most patients. ### Role of Other Agents - **Finasteride:** 5-alpha reductase inhibitor; indicated for large prostate glands (>40 g) and elevated PSA. Takes 6–12 months for symptom improvement. Reserved for second-line or combination therapy. - **Doxazosin:** Non-selective α1-blocker; effective but higher incidence of orthostatic hypotension and syncope; used as alternative if tamsulosin unavailable. - **Tadalafil:** Phosphodiesterase-5 inhibitor; emerging agent for LUTS/BPH; not standard first-line; used in patients with concurrent erectile dysfunction. **Clinical Pearl:** In a patient with post-void residual <100 mL and no acute retention, medical management with α1-blockers is appropriate. If PVR >100 mL or acute retention occurs, consider TURP or other surgical intervention. [cite:Harrison 21e Ch 305]