Alfuzosin

Pharmacologic Class

  • Selective α₁-adrenergic receptor antagonist (α₁-blocker)
  • Specifically uroselective — preferentially blocks α₁A receptors in the prostate and bladder neck.

Mechanism of Action

  • Alfuzosin blocks postsynaptic α₁-adrenergic receptors in the lower urinary tract, including the prostate, bladder base, bladder neck, and prostatic urethra.
  • This reduces smooth muscle tone, leading to:
    • ↓ bladder outlet resistance
    • ↓ urethral pressure
    • Improved urinary flow
    • ↓ BPH-related symptoms (hesitancy, incomplete emptying, weak stream)
    • Unlike older α₁-blockers (e.g., doxazosin, terazosin), alfuzosin is more uroselective, resulting in fewer systemic vascular effects (e.g., less orthostatic hypotension).

Indications

  • Benign Prostatic Hyperplasia (BPH) — to improve lower urinary tract symptoms (LUTS).
    • Symptom relief (does not reduce prostate size or halt progression).
    • May be used as monotherapy or in combination with 5-α reductase inhibitors (e.g., finasteride, dutasteride).

Dosing

Population Typical Dose Comments
Adults (Men) 10 mg once daily Give immediately after the same meal each day (improves absorption and reduces first-dose hypotension).
Renal impairment Use with caution if CrCl <30 mL/min Limited data. Avoid if severe renal impairment.
Hepatic impairment Contraindicated in moderate to severe hepatic impairment ↑ systemic exposure due to hepatic metabolism (CYP3A4).

Contraindications

  • Moderate to severe hepatic impairment
  • Concomitant use with potent CYP3A4 inhibitors (e.g., ketoconazole, ritonavir, clarithromycin)
  • History of postural hypotension or syncope with α-blockers

Adverse Effects

System Common Effects Clinical Notes
Cardiovascular Orthostatic hypotension, dizziness, syncope Especially after the first dose or dose increase; advise patients to rise slowly.
Neurologic Headache, fatigue Usually transient.
Genitourinary Retrograde ejaculation Due to relaxation of bladder neck.
GI Nausea Mild, dose-related.

Less likely to cause orthostatic hypotension than doxazosin or terazosin because of relative uroselectivity.

Drug Interactions

Interacting Drug/Class Mechanism Effect/Recommendation
CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir) ↓ Alfuzosin metabolism ↑ levels → hypotension; avoid.
Other α-blockers / PDE-5 inhibitors (e.g., sildenafil, tadalafil) Additive vasodilation ↑ risk of hypotension; start low, space doses.
Antihypertensives Additive BP lowering Monitor BP and symptoms.

Pharmacokinetics

Parameter Detail
Absorption Enhanced with food (bioavailability ↑ by ~50% with meal)
Metabolism Extensive hepatic via CYP3A4
Elimination Fecal (major) and renal (minor)
Half-life ~10 hours
Onset of action Within few days; full effect within 2–3 weeks

Clinical Pearls

  • Counsel patients:
    • Take immediately after the same meal each day (preferably dinner).
    • Avoid sudden position changes to reduce risk of dizziness/fainting.
    • May cause ejaculatory dysfunction (harmless but notable for adherence).
  • Monitor:
    • BP (especially orthostatic)
    • LUTS improvement (AUA symptom score)
    • Signs of syncope or dizziness
  • Surgical alert:
    • May cause Intraoperative Floppy Iris Syndrome (IFIS) during cataract surgery — notify ophthalmologist if patient uses or used alfuzosin or any α-blocker.

Comparison with Other α₁-Blockers

Drug Selectivity Dosing Hypotension Risk Unique Point
Tamsulosin Highly uroselective (α₁A) Once daily Low Ejaculatory issues more common
Alfuzosin Functionally uroselective Once daily Low Well-tolerated, food-dependent absorption
Doxazosin / Terazosin Non-selective Once daily High Useful if concurrent hypertension
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