Recommended Dosage of Silodosin (Silodal) for BPH Treatment
The recommended dose of silodosin for the treatment of Benign Prostatic Hyperplasia (BPH) is 8 mg taken orally once daily with a meal, with a reduced dose of 4 mg once daily for patients with moderate renal impairment (creatinine clearance 30-50 mL/min). 1
Dosing Guidelines
- Standard dosage: 8 mg capsule taken orally once daily with a meal 1
- Moderate renal impairment (CCr 30-50 mL/min): 4 mg capsule taken orally once daily with a meal 1
- Contraindicated in:
Mechanism and Efficacy
Silodosin is a selective α1A-adrenergic receptor antagonist that works by relaxing smooth muscle in the prostate and urethra, thereby improving urinary symptoms associated with BPH 2. Its high selectivity for α1A receptors (583 times greater affinity compared to α1B receptors) minimizes blood pressure-related adverse effects that are typically mediated by α1B blockade 2.
Clinical studies have demonstrated that silodosin at 8 mg daily significantly improves:
- International Prostate Symptom Score (IPSS) 2, 3
- Maximum urinary flow rate (Qmax) 2, 3
- Both storage and voiding symptoms, with an early onset of efficacy 3
Adverse Effects
The most common adverse effects include:
- Retrograde ejaculation (>22% of patients) 1, 2
- Dizziness 1
- Diarrhea 1
- Orthostatic hypotension (low incidence <3%) 2
- Headache 1
- Nasopharyngitis 1
- Nasal congestion 1
Important Considerations
- Take silodosin with a meal to enhance absorption 1
- Monitor for orthostatic hypotension, especially when initiating therapy 1
- Patients planning cataract surgery should inform their ophthalmologist about silodosin use due to the risk of Intraoperative Floppy Iris Syndrome (IFIS) 1
- Do not use in combination with other alpha-blockers 1
- Use caution when combining with PDE5 inhibitors due to potential for symptomatic hypotension 1
- Long-term studies have demonstrated continued safety and efficacy of silodosin 4
Monitoring
- Assess symptom improvement using the International Prostate Symptom Score (IPSS)
- Monitor for adverse effects, particularly retrograde ejaculation
- Evaluate renal function before and periodically during treatment
Silodosin represents an effective option for BPH treatment with minimal cardiovascular side effects due to its high selectivity for α1A receptors, making it particularly suitable for elderly patients or those with cardiovascular comorbidities 3, 5.