Alpha Blockers: Clinical Indications and Applications
Primary Indication: Benign Prostatic Hyperplasia (BPH)
Alpha blockers are primarily used to treat lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia by blocking alpha1-adrenergic receptors in prostatic smooth muscle, thereby relieving bladder outlet obstruction. 1
Mechanism of Action
- Alpha blockers work by inhibiting alpha1-adrenergic-mediated contraction of prostatic smooth muscle, which reduces bladder outlet obstruction and improves urinary flow 1
- This mechanism targets the dynamic component of BPH rather than prostate size itself 1
Recommended Agents for BPH/LUTS
First-Line Options
The following alpha blockers are appropriate treatment options for patients with bothersome, moderate to severe LUTS secondary to BPH 1:
- Alfuzosin
- Doxazosin
- Silodosin
- Tamsulosin
- Terazosin
Expected Efficacy
- All approved alpha blockers produce similar symptom improvement, averaging a 4-6 point improvement in the AUA Symptom Index compared to placebo (2-4 points) 1
- Patients generally perceive this level of symptom improvement as meaningful 1
- Efficacy is dose-dependent for titratable agents (doxazosin and terazosin), with higher doses producing greater improvement 1
Agent Selection Algorithm
Preferred First-Line Choice
Tamsulosin 0.4 mg once daily should be the initial choice for most patients because it requires no dose titration, provides equal efficacy to other agents, and has the lowest cardiovascular side effect burden 2, 3, 4
When Ejaculatory Function is Priority
Alfuzosin 10 mg once daily is recommended when preserving ejaculatory function is important, as it has significantly lower rates of ejaculatory dysfunction compared to tamsulosin 2
Patients with Cardiovascular Considerations
- Uroselective agents (tamsulosin, alfuzosin) have significantly better tolerability than non-selective agents (doxazosin, terazosin) with lower rates of orthostatic hypotension, dizziness, and fatigue 2, 3
- Tamsulosin produces minimal blood pressure reductions and does not significantly affect orthostatic blood pressure control 3, 4
- Doxazosin and terazosin should be avoided in patients with cardiac risk factors, as doxazosin monotherapy was associated with higher incidence of congestive heart failure 1
Secondary Indication: Hypertension
Historical Use
- Alpha1 blockers (particularly doxazosin and terazosin) were previously used for hypertension management by targeting elevated peripheral vascular resistance 5
- They maintain cardiac output and blood flow to vital organs without affecting renin release 5
Current Hypertension Management Considerations
Alpha blockers used for BPH should NOT be relied upon for optimal hypertension management 1
- Patients with concomitant hypertension require separate, optimized antihypertensive therapy 2
- Alpha blockers are not first-line therapies for hypertension, and most hypertensive BPH patients will be receiving other antihypertensive agents 6
Common Adverse Effects
Cardiovascular Side Effects
- Orthostatic hypotension 1, 7
- Dizziness (2.8% placebo vs 5.7% with alfuzosin) 7
- Syncope 7
- Fatigue/asthenia 1
Other Side Effects
- Ejaculatory dysfunction (highest with tamsulosin) 1, 2
- Nasal congestion 1
- Headache 7
- Upper respiratory tract infection 7
Ophthalmologic Considerations
Patients with planned cataract surgery should be informed of Intraoperative Floppy Iris Syndrome (IFIS) risk and should delay alpha blocker initiation until after the procedure 1, 7
Agents NOT Recommended
Prazosin and phenoxybenzamine have insufficient data to support their use for LUTS secondary to BPH 1
Special Clinical Situations
Acute Urinary Retention
Oral alpha blockers (alfuzosin or tamsulosin) should be prescribed prior to voiding trial for acute urinary retention related to BPH, with patients completing at least 3 days of therapy before attempting trial without catheter 2
Combination Therapy
- Combination therapy with 5-alpha reductase inhibitors reduces clinical progression of BPH more effectively than monotherapy in patients with enlarged prostates (>30cc volume or PSA >1.5 ng/mL) 1, 2
- The combination reduces long-term risk of acute urinary retention and need for BPH-related surgery 1