Alpha-1A Selective Blocker
Pregnancy: Not applicable
Silodosin
Brand names: Urorec, Silodyx
Adult dose
Dose: 8 mg once daily with a meal
Route: oral
Frequency: once daily
Max: 8 mg/day
Highly selective alpha-1A; take with main meal; reduce to 4 mg/day if eGFR 30–50 ml/min; most selective agent — less blood pressure effect
Paediatric dose
Route:
Not licensed in children
Dose adjustments
Renal
4 mg once daily if eGFR 30–50 ml/min; avoid if eGFR <30 ml/min
Hepatic
Avoid in severe hepatic impairment
Clinical pearls
- Highest alpha-1A selectivity of all alpha-blockers — predominantly acts on bladder outlet
- Retrograde ejaculation in ~28% — important counselling point for sexually active men
- Less cardiovascular side effects than non-selective alpha-1 blockers
Contraindications
- eGFR <30 ml/min
- Severe hepatic impairment
- Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir)
Side effects
- Retrograde ejaculation (most common — 28%)
- Orthostatic hypotension (less than other alpha-blockers)
- Diarrhoea
- Nasal congestion
- Intraoperative floppy iris syndrome
Interactions
- PDE5 inhibitors (hypotension)
- Strong CYP3A4 inhibitors (CI)
- P-glycoprotein inhibitors
Monitoring
- Blood pressure
- Ejaculatory function
- IPSS scores
Reference: BNFc; BNF 86; NICE NG97; EAU Guidelines on BPH. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators