Can Flomax (tamsulosin) be used to treat urinary retention?

Can Flomax (Tamsulosin) Be Used for Urinary Retention?

Yes, tamsulosin should be prescribed for acute urinary retention (AUR) related to benign prostatic hyperplasia (BPH), as it significantly improves the success rate of voiding after catheter removal and reduces the need for re-catheterization. 1

Evidence-Based Recommendation for Acute Urinary Retention

Primary Treatment Protocol

The American Urological Association (AUA) provides a Moderate Recommendation (Evidence Level: Grade B) that physicians should prescribe an oral alpha blocker prior to a voiding trial to treat patients with AUR related to BPH. 1

• Administer tamsulosin 0.4 mg daily for at least 3 days before attempting catheter removal (trial without catheter, TWOC). 1
• This 3-day minimum treatment duration is based on expert opinion and allows adequate time for the medication to exert its therapeutic effect. 1

Clinical Efficacy Data

The evidence supporting tamsulosin use in AUR is robust:

• Tamsulosin increases successful voiding after catheter removal to 47-61% compared to 26-39% with placebo. 1, 2
• A high-quality randomized controlled trial demonstrated that 48% of men taking tamsulosin voided successfully versus 26% on placebo (p = 0.011; odds ratio 2.47). 2
• Chinese studies showed even higher success rates of 61% with tamsulosin versus 28% in controls (p < 0.01). 3

Important Caveats and Patient Counseling

Patients who successfully void after AUR treatment with alpha blockers remain at significantly increased risk for recurrent urinary retention. 1 This is a critical counseling point:

• All clinical trials report substantial numbers of patients experiencing subsequent retention days to months later, requiring re-catheterization or surgical intervention. 1
• Long-term efficacy of alpha blocker therapy in treating AUR remains unclear due to lack of standardized long-term follow-up in studies. 1

When Tamsulosin Is NOT Appropriate

Surgery remains the definitive treatment for refractory retention—defined as failure after at least one attempt at catheter removal with alpha blocker therapy. 1

For patients who are not surgical candidates with refractory retention, alternative management includes:

• Intermittent catheterization 1
• Indwelling catheter 1
• Urethral stent 1

Contraindications to Alpha Blocker Trial

Do not attempt alpha blocker therapy in patients with:

• Prior history of alpha-blocker side effects 1
• Unstable medical comorbidities such as orthostatic hypotension or cerebrovascular disease that increase risks associated with alpha-blocker therapy 1

Predictors of Success vs. Failure

A voiding trial is more likely to succeed when AUR is precipitated by temporary factors such as:

• Anesthesia 1
• Alpha-adrenergic sympathomimetic cold medications 1

Predictors of medical therapy failure include:

• Poor quality-of-life score on initial International Prostate Symptom Score (IPSS) (p = 0.038) 4
• High post-void residual volume at 2 weeks after catheter removal (p = 0.013) 4

Surgical Indications

Surgery is recommended for patients with serious BPH complications including:

• Refractory retention after failed catheter removal attempt 1
• Renal insufficiency clearly due to BPH 1
• Recurrent urinary tract infections due to BPH 1
• Recurrent gross hematuria due to BPH 1
• Bladder stones clearly due to BPH 1

Practical Clinical Approach

1. Catheterize the patient and initiate tamsulosin 0.4 mg daily 1, 2
2. Continue treatment for minimum 3 days 1
3. Remove catheter and attempt voiding trial 1
4. If successful, continue tamsulosin and counsel about recurrence risk 1
5. If unsuccessful after one attempt, refer for surgical evaluation 1

Side Effect Profile

The side-effect profile of tamsulosin in AUR patients is similar to placebo and consistent with known alpha-blocker pharmacology. 2 The most commonly reported adverse events include:

• Dizziness (10% with tamsulosin vs. 3% with placebo) 2
• Somnolence (6% with tamsulosin vs. 3% with placebo) 2