What is the recommended treatment for benign prostatic hyperplasia (BPH) using Sildosin (Rapaflo)?

Silodosin for Benign Prostatic Hyperplasia

Recommended Dosing and Administration

Silodosin 8 mg orally once daily with a meal is the standard recommended dose for treating signs and symptoms of BPH. 1

• The capsule may be opened and sprinkled on applesauce (swallowed within 5 minutes without chewing, followed by 8 oz of cool water) for patients with difficulty swallowing, though subdividing capsule contents is not recommended 1
• Dose reduction to 4 mg once daily is required for patients with moderate renal impairment (creatinine clearance 30-50 mL/min) 1
• No dosage adjustment is needed for mild renal impairment (creatinine clearance 50-80 mL/min) or mild-to-moderate hepatic impairment 1

Role in BPH Treatment Algorithm

Silodosin functions as a first-line alpha-blocker option alongside alfuzosin, doxazosin, tamsulosin, and terazosin for patients with bothersome moderate-to-severe BPH symptoms (AUA Symptom Score >8). 2

• Alpha-blockers as a class produce 4-6 point improvements in symptom scores, which patients perceive as meaningful change 3, 2
• Silodosin demonstrates high selectivity for α1A-adrenoceptors (583-fold higher affinity than α1B and 55.5-fold higher than α1D), providing uroselectivity 4, 5, 6
• Efficacy is at least equivalent to tamsulosin 0.4 mg daily, with significantly greater effectiveness for simultaneous improvement of incomplete emptying, frequency, and nocturia 4, 5
• Onset of action is rapid, with improvements documented within 2-6 hours to 1 day, and effects remain stable for up to 6 years 7, 6, 8

Adverse Effect Profile

The most distinctive adverse effect is abnormal ejaculation (retrograde ejaculation/anejaculation), occurring in approximately 28% of patients, though only 2.8-3.9% discontinue treatment because of this. 4, 5, 6

• Silodosin has minimal cardiovascular effects, with orthostatic hypotension rates (2.6%) similar to placebo (1.5%) 5, 6
• This contrasts with doxazosin and terazosin, which have higher orthostatic hypotension risk and require dose titration 2
• Tamsulosin shares the lower orthostatic hypotension profile but also has higher ejaculatory dysfunction risk compared to non-uroselective alpha-blockers 3, 2
• Patients should be cautioned about driving, operating machinery, or performing hazardous tasks when initiating therapy due to potential postural hypotension and dizziness 1

Critical Contraindications and Warnings

Silodosin is absolutely contraindicated in patients with severe renal impairment (creatinine clearance <30 mL/min), severe hepatic impairment (Child-Pugh score ≥10), and concomitant use with strong CYP3A4 inhibitors (ketoconazole, clarithromycin, itraconazole, ritonavir). 1

• For patients planning cataract surgery, inform ophthalmologists about alpha-blocker use due to intraoperative floppy iris syndrome (IFIS) risk, and consider delaying silodosin initiation until after surgery 2, 5
• Silodosin is not indicated for hypertension treatment, and alpha-blockers should not be assumed to constitute optimal hypertension management, especially in men with cardiac risk factors 3, 2, 1

Patient Selection Considerations

Silodosin is most appropriate for patients prioritizing rapid symptom relief with minimal cardiovascular effects who can tolerate potential ejaculatory dysfunction. 4, 7

• Patients with smaller prostates (<44 mL) have higher continuation rates at 6 years compared to those with larger prostates 8
• The 25% continuation rate at 72 months reflects that 28.8% withdrew due to unsatisfactory effects (most requiring surgery), suggesting silodosin works well for appropriately selected patients but does not prevent disease progression requiring surgery in all cases 8
• Concomitant use with phosphodiesterase type 5 inhibitors and antihypertensive agents is feasible 5