Tamsulosin Dose Escalation or Silodosin Switch Before Trial Without Catheter in BPH-Related Acute Urinary Retention

Acute urinary retention is a common emergency complication of benign prostatic hyperplasia. Standard management includes immediate bladder decompression by urethral catheterization followed by alpha-blocker therapy before attempting catheter removal. However, the optimal management strategy is unclear in men who develop acute urinary retention despite already receiving standard-dose tamsulosin 0.4 mg once daily.

This trial is designed to evaluate whether continuing tamsulosin 0.4 mg, increasing the dose to tamsulosin 0.8 mg, or switching to silodosin 8 mg provides better clinical outcomes before trial without catheter. Eligible men aged 50 years or older with painful acute urinary retention presumed to be secondary to benign prostatic enlargement or obstruction, and who were already taking tamsulosin 0.4 mg once daily for at least 4 weeks before the retention episode, will be enrolled after successful urethral catheterization and written informed consent.

Participants will be randomized in a 1:1:1 ratio to one of three parallel treatment arms. The assigned medication will be given for 7 days while the urethral catheter remains in place. On Day 7, the catheter will be removed in the outpatient urology clinic. Trial without catheter success will be assessed using a predefined clinical definition based on spontaneous voiding, voided volume, post-void residual urine measured by ultrasound, absence of clinically significant voiding difficulty, and no need for re-catheterization within 24 hours.

Participants will be followed until Day 30 for urinary outcomes and safety assessment. The study will also record adverse drug events and catheter-related complications. Participants who fail the Day-7 trial without catheter will be managed according to standard clinical care, including re-catheterization and possible rescue trial without catheter or further benign prostatic hyperplasia management according to clinical judgment.

• Tamsulosin 0.4 mg (Drug): Participants assigned to this intervention will continue tamsulosin 0.4 mg once daily for 7 days during urethral catheterization before Trial Without Catheter at Day 7.
• Tamsulosin 0.8 mg (Drug): Participants assigned to this intervention will receive tamsulosin 0.8 mg once daily for 7 days during urethral catheterization before Trial Without Catheter at Day 7.
• Silodosin 8 mg (Drug): Participants assigned to this intervention will stop tamsulosin 0.4 mg and switch to silodosin 8 mg once daily for 7 days during urethral catheterization before Trial Without Catheter at Day 7.

Primary outcomes

• Successful Trial Without Catheter at Day 7 [Day 7, with assessment continuing for 24 hours after catheter removal]: Proportion of participants with successful Trial Without Catheter at Day 7. Success is defined as spontaneous voiding within 6 hours after urethral catheter removal, voided volume ≥100 mL, post-void residual urine <150 mL measured by ultrasound within 10-15 minutes after voiding, no painful bladder distension or clinically significant voiding difficulty requiring immediate re-catheterization, and no need for re-catheterization within 24 hours after catheter removal.

Secondary outcomes

• Catheter-Free Status at Day 14 [Day 14]: Proportion of participants who are free from an indwelling urinary catheter at Day 14 after randomization, including participants who undergo rescue Trial Without Catheter after initial Day-7 failure.
• Recurrent Acute Urinary Retention Within 30 Days [Up to 30 days]: Proportion of participants who develop recurrent acute urinary retention requiring re-catheterization after initially successful Trial Without Catheter.
• Adverse Drug Events [Up to 30 days]: Proportion of participants with adverse drug events, including dizziness, postural hypotension, syncope, headache, nasal congestion, abnormal ejaculation, diarrhea, allergic reaction, or other clinically significant drug-related adverse events.

Sex: Male, ages: 50 Years to any

Inclusion Criteria:

* Male patients aged 50 years or older.
* Acute urinary retention requiring urethral catheterization.
* Presumed acute urinary retention secondary to benign prostatic enlargement or benign prostatic obstruction.
* Already receiving tamsulosin 0.4 mg once daily for at least 4 weeks before the acute urinary retention episode.
* Successful urethral catheterization at presentation.
* Initial catheterized urine volume ≤1000 mL, with a clinical presentation consistent with painful acute urinary retention.
* Prostate enlargement on ultrasound or clinical assessment consistent with benign prostatic hyperplasia or benign prostatic obstruction.
* Ability to provide written informed consent.

Exclusion Criteria:

* Known or suspected prostate cancer.
* Previous prostate surgery.
* Previous urethral stricture disease or urethral surgery.
* Neurogenic bladder or known neurological disease affecting voiding.
* Chronic urinary retention rather than acute painful retention.
* Acute urinary retention due to non-BPH causes, including clot retention, bladder stone obstruction, acute prostatitis, urethral trauma, or drug-induced retention.
* Severe urinary tract infection, sepsis, or fever at presentation.
* Gross hematuria requiring irrigation.
* Failed urethral catheterization or need for suprapubic catheterization.
* Current use of silodosin, alfuzosin, doxazosin, terazosin, tadalafil, anticholinergics, beta-3 agonists, or other drugs that may significantly affect voiding.
* Severe renal impairment requiring urgent intervention.
* Symptomatic postural hypotension or recurrent syncope.
* Known hypersensitivity to silodosin.
* Severe hepatic impairment.
* Inability to comply with follow-up.