What medications are used to treat overflow incontinence in men with benign prostatic hyperplasia (BPH)?

Medication Management for Overflow Incontinence in Men with BPH

The primary medical treatment for overflow incontinence in men with BPH is alpha-1 adrenergic blockers (tamsulosin, doxazosin, alfuzosin, terazosin) to relieve bladder outlet obstruction, combined with 5-alpha reductase inhibitors (finasteride, dutasteride) for men with enlarged prostates (>40 ml) to reduce prostate size and prevent progression. 1

Understanding Overflow Incontinence in BPH

Overflow incontinence occurs when bladder outlet obstruction from prostatic enlargement prevents complete bladder emptying, leading to chronic urinary retention and involuntary leakage. 2, 3 The treatment strategy must address the underlying obstruction rather than the incontinence itself.

First-Line Pharmacological Approach

Alpha-1 Adrenergic Blockers

Alpha-blockers are the treatment of choice for bladder outlet obstruction symptoms in men with BPH. 1

• Tamsulosin 0.4 mg once daily (can increase to 0.8 mg after 2-4 weeks if inadequate response) 4
• Alternative agents include doxazosin, alfuzosin, and terazosin 1, 5
• These medications relax prostatic smooth muscle, improving urinary flow and reducing post-void residual volumes 1
• Assess treatment response at 2-4 weeks after initiation 1

5-Alpha Reductase Inhibitors

For men with moderate-to-severe symptoms AND enlarged prostates (>40 ml) or PSA >1.5 ng/ml, add a 5-ARI to reduce prostate size and prevent disease progression. 1

• Finasteride 5 mg once daily reduces prostate volume and decreases risk of acute urinary retention and need for surgery 6
• Requires at least 3 months to assess efficacy due to slow onset of action 1
• Reduces risk of acute urinary retention by approximately 57% and need for surgery by 55% in long-term studies 1

Combination Therapy

Combination therapy with an alpha-blocker plus 5-ARI is superior to monotherapy for long-term symptom control and reducing progression risk in men with enlarged prostates. 1

• Reduces clinical progression risk by 66% versus placebo, 34% versus finasteride alone, and 39% versus doxazosin alone 1
• Reduces relative risk of acute urinary retention by 68% and BPH-related surgery by 71% compared to tamsulosin alone at 4 years 1
• Number needed to treat: 13 patients for 4 years to prevent one case of urinary retention or surgical intervention 1
• Higher adverse event rate than monotherapy, including sexual dysfunction, dizziness, and postural hypotension 1, 6

Critical Management Considerations

Post-Void Residual Monitoring

Measure post-void residual (PVR) volume before initiating treatment and during follow-up to assess response and guide therapy. 7

• PVR >150 ml indicates significant retention and may require more aggressive intervention 1, 7
• Serial PVR measurements help determine if medical therapy is adequately relieving obstruction 7

Medications to AVOID

Do NOT use antimuscarinic agents (tolterodine, solifenacin, oxybutynin) or beta-3 agonists (mirabegron) as monotherapy in men with overflow incontinence. 1, 7

• These medications treat overactive bladder/storage symptoms, NOT overflow incontinence 1
• Antimuscarinics can worsen urinary retention by reducing detrusor contractility 1, 7
• Only consider adding these agents if storage symptoms (urgency, frequency) persist AFTER relieving obstruction with alpha-blockers, and only if PVR <150 ml 1, 7

Treatment Algorithm

1. Initial Assessment: Measure PVR, assess prostate size (digital rectal exam or ultrasound), check PSA 1

2. Start Alpha-Blocker: Tamsulosin 0.4 mg daily or equivalent 1, 4

3. Add 5-ARI if: Prostate volume >40 ml OR PSA >1.5 ng/ml OR high risk of progression 1

4. Reassess at 2-4 weeks (alpha-blocker) and 3 months (5-ARI) 1

5. If inadequate response: Increase tamsulosin to 0.8 mg OR refer for urodynamic studies and surgical evaluation 1, 4

When Medical Therapy Fails

Refer for surgical intervention if symptoms persist despite optimal medical therapy, PVR remains elevated, or complications develop (recurrent retention, bladder stones, renal insufficiency). 1

• Transurethral resection of the prostate (TURP) remains the gold standard surgical treatment 1
• Alternative procedures include holmium laser enucleation and photovaporization 7

Common Pitfalls

• Misdiagnosing overflow incontinence as overactive bladder and prescribing antimuscarinics, which can precipitate acute urinary retention 1, 7
• Failing to measure PVR before initiating therapy, missing significant retention 7
• Expecting rapid results from 5-ARIs, which require 3-6 months for maximal effect 1
• Not counseling about sexual side effects of 5-ARIs (decreased libido, erectile dysfunction, ejaculatory disorders affect 5-10% of patients) 6