Overview
Silodosin is a selective alpha-1A adrenergic receptor antagonist used to treat the signs and symptoms of benign prostatic hyperplasia (BPH). It works by relaxing smooth muscle in the prostate and bladder neck, improving urinary flow. It is not indicated for hypertension treatment.
Mechanism of Action
Selectively blocks alpha-1A adrenergic receptors in the prostate, bladder neck, and prostatic urethra, causing smooth muscle relaxation and improved urinary flow without significant effects on blood pressure.
Indications
- Treatment of signs and symptoms of benign prostatic hyperplasia (BPH)
Common Doses
- 8 mg
Dosage
8 mg orally once daily with a meal. Dose adjustment required for moderate renal impairment (CrCl 30-50 mL/min). Not recommended in severe renal impairment (CrCl <30 mL/min).
Contraindications
- Severe renal impairment (CrCl <30 mL/min)
- Severe hepatic impairment
- Concomitant use with strong CYP3A4 inhibitors
Side Effects
- Retrograde ejaculation
- Dizziness
- Orthostatic hypotension
- Diarrhea
- Headache
- Nasal congestion
- Increased post-void residual volume
Interactions
- Strong CYP3A4 inhibitors (ketoconazole, clarithromycin, ritonavir) - contraindicated
- Moderate CYP3A4 inhibitors - use with caution
- Alpha-blockers - additive hypotensive effects
- Phosphodiesterase-5 inhibitors - potential additive hypotension
Counseling Points
- Take with same meal each day
- Rise slowly from sitting/lying position to avoid dizziness
- Report dizziness, lightheadedness, or fainting
- Inform ophthalmologist about silodosin use before cataract surgery
- May cause retrograde ejaculation (dry orgasm)