Treatment of Benign Prostatic Hyperplasia (BPH)

Mechanism of Action and Efficacy

Alpha-blockers like doxazosin work by inhibiting alpha1-adrenergic-mediated contraction of prostatic smooth muscle, relieving bladder outlet obstruction caused by BPH, with efficacy being dose-dependent, and higher doses providing greater observed improvement 1
The American Urological Association guidelines note that efficacy is dose-dependent for doxazosin, with higher doses providing greater improvement, and fixed-dose studies demonstrated significant and sustained improvement in maximum urinary flow rate compared to placebo 1

For patients with acute urinary retention related to BPH, prescribe an oral alpha blocker (like doxazosin) prior to a voiding trial, and complete at least three days of therapy before attempting trial without catheter, with patients who successfully void remaining at increased risk for recurrent retention 2

Common adverse events include orthostatic hypotension, dizziness, tiredness, ejaculatory problems, and nasal congestion, with monitoring of blood pressure and post-void residual (PVR) being important considerations 1, 2

In patients with both hypertension and BPH, doxazosin can treat both conditions simultaneously, but separate management of hypertension may be required in some cases, and alpha-blockers like doxazosin can potentially worsen ejaculatory function 1, 3
Patients with larger prostate volumes may benefit from combination therapy with a 5-alpha reductase inhibitor for long-term management 1