Finasteride Therapy for Benign Prostatic Hyperplasia

Patient Selection

• The American Urological Association indicates that finasteride is appropriate for patients with lower urinary tract symptoms (LUTS) who have evidence of prostatic enlargement, defined as a prostate volume greater than 30cc on imaging 1
• Finasteride is not recommended for men with LUTS who do not have evidence of prostatic enlargement 2, 3, 4

Mechanism of Action and Effects

• Finasteride inhibits 5-alpha-reductase type II isoenzyme, reducing dihydrotestosterone (DHT) in the prostate by approximately 70%, leading to a 15-25% reduction in prostate size within 6 months 1
• Finasteride therapy results in an increase in peak urinary flow rate 2
• Finasteride reduces benign prostatic hyperplasia (BPH) symptoms 2
• Finasteride decreases serum PSA levels by approximately 50% 1

Clinical Efficacy

• Patients experience an average 3-point improvement in the AUA Symptom Index with finasteride therapy, which is generally perceived as a meaningful change 2, 4
• Long-term studies show symptom score improvements of 3-4 points maintained for 6-10 years with finasteride 1
• Finasteride provides greater benefit in men with larger prostates and/or higher PSA values 1, 2

Side Effects

• Decreased libido is a common side effect of finasteride, occurring in 6.4% of patients in the first year and 2.6% in years 2-4 3
• Ejaculatory dysfunction is another side effect, occurring in 3.7% of patients in the first year and 1.5% in years 2-4 4
• These side effects are typically reversible and become less common after the first year of therapy 2, 4

Important Considerations

• Finasteride is less effective than alpha blockers for immediate symptom relief but provides long-term benefits in reducing disease progression 1, 2
• When screening for prostate cancer in men on finasteride, the measured PSA value should be doubled after 1 year of therapy to accurately assess disease progression 1
• Combination therapy with an alpha blocker may be more effective than finasteride monotherapy for patients with very large prostates or severe symptoms 5

Common Pitfalls to Avoid

• Inadequate treatment duration is a common pitfall, as finasteride has a slower onset of action compared to alpha blockers; patients should be counseled that symptom improvement may take several months 1
• Using finasteride in patients without prostatic enlargement is ineffective 2, 4
• Failure to adjust PSA interpretation is a common pitfall, as PSA levels decrease by approximately 50% after 12 months of therapy 1

Finasteride for BPH with LUTS in Patients on Testosterone Supplementation

Mechanism of Action and Rationale

• Finasteride inhibits the 5-alpha-reductase type II isoenzyme, reducing dihydrotestosterone (DHT) in the prostate, and does not lower serum testosterone to castration levels, making it compatible with testosterone supplementation 6
• The medication specifically targets the conversion of testosterone to DHT in prostatic tissue, allowing testosterone supplementation to continue while addressing prostate enlargement 6

Efficacy for BPH with LUTS

• Finasteride provides an average 3-point improvement in the AUA Symptom Index, which is generally perceived as a meaningful clinical change 6

Important Patient Selection Criteria

• Finasteride is most effective in patients with demonstrable prostatic enlargement (prostate volume >30cc) 6
• Finasteride is ineffective in patients who do not have enlarged prostates 6, 7

Combination Therapy Considerations

• Combination therapy with an alpha-blocker and finasteride is more effective than finasteride alone for immediate symptom relief 6

Algorithm for Treatment

• Confirm prostatic enlargement (>30cc) before initiating finasteride 6
• For immediate symptom relief, consider starting with combination therapy (finasteride + alpha-blocker) 6
• Continue testosterone supplementation as finasteride specifically targets prostatic DHT without affecting serum testosterone 6

Treatment for Benign Prostatic Enlargement Grade 3

Understanding Grade 3 BPH

• The American Urological Association recommends initiating combination therapy with both an alpha-blocker and a 5-alpha reductase inhibitor (5-ARI) for Grade 3 BPH, as this approach is superior to monotherapy in preventing disease progression, reducing the risk of acute urinary retention, and decreasing the need for future surgery 8

First-Line Medical Therapy: Combination Treatment

• The combination of an alpha-blocker and a 5-ARI is recommended for Grade 3 BPH, as it provides both immediate symptom relief and long-term disease modification, with alpha-blockers such as Doxazosin and Terazosin providing a 3.60-7.06 and 3.22-6.76 point improvement in IPSS, respectively 8
• The European Association of Urology suggests that the choice of alpha-blocker should be based on patient age, cardiovascular comorbidities, and sexual function concerns, with Silodosin having higher rates of ejaculatory dysfunction but being effective 8

Why Combination Therapy for Grade 3 BPH

• Combination therapy with alpha-blocker plus 5-ARI is superior to monotherapy because it prevents progression of LUTS/BPH, reduces risk of acute urinary retention, and reduces need for future prostate-related surgery, providing both immediate symptom relief and long-term disease modification 8

When Medical Therapy Fails

• The American Urological Association recommends referring patients for urologic evaluation and surgical consideration if they experience refractory urinary retention, recurrent urinary tract infections, recurrent gross hematuria, bladder stones, or renal insufficiency clearly due to BPH, with surgery being the most effective treatment for these complications 8, 9

Follow-Up Protocol

• The American Urological Association suggests monitoring patients using the International Prostate Symptom Score (IPSS) at each visit, with alpha-blocker response assessed at 2-4 weeks and 5-ARI response assessed at 6 months minimum 8

Finasteride Therapy Monitoring and Management

Patient Assessment and Monitoring

• The American Urological Association recommends monitoring PSA levels in patients on finasteride therapy, with a doubling adjustment after 6 months of therapy to accurately interpret results 10, 11
• Patients on finasteride therapy should be assessed for breast changes, such as gynecomastia or breast tenderness, which can occur in some individuals 12
• A digital rectal exam (DRE) should be performed to assess prostate size, nodularity, asymmetry, and tenderness in patients on finasteride therapy 10

Treatment Response and Duration

• Finasteride therapy can reduce the risk of prostate cancer, but may also increase the risk of high-grade prostate cancer, with a reported incidence of 1.8% vs 1.1% in the placebo group 12
• The treatment duration for finasteride therapy can vary, with long-term therapy indicated for benign prostatic hyperplasia (BPH) and a 7-year duration studied for cancer prevention 12

Medication Management and Patient Education

• Patients should be educated on the potential sexual side effects of finasteride therapy, including erectile dysfunction and decreased libido, which can occur in 4-15% and 6.4% of patients, respectively 12
• Patients should also be informed that finasteride reduces the risk of prostate cancer, but may increase the risk of high-grade prostate cancer, and that they should not donate blood until 6 months after last dose due to the risk to pregnant females 12

Discontinuation of Finasteride in Patients with Chronic Indwelling Foley Catheters

Guideline Recommendations (AUA/SUFU)

• The American Urological Association (AUA) and the Society for Urologic Female (SUFU) guidelines state that chronic indwelling catheters should be used only when BPH therapies—including finasteride—are contraindicated, ineffective, or no longer desired, and that the decision must involve shared decision‑making because of potential harms. 13
• According to the same AUA/SUFU guidelines, chronic catheterization is positioned after failure of medical therapies rather than as a concurrent treatment strategy. 13
• The AUA/SUFU guidelines recommend discontinuing oral BPH medications once patients have transitioned to alternative management (e.g., chronic catheterization) and advise restarting them only if the alternative fails and urinary symptoms recur. 13

Clinical Rationale

• Patients who require a chronic indwelling Foley catheter have already experienced treatment failure that finasteride is designed to prevent (e.g., acute urinary retention and need for BPH‑related surgery), making continued finasteride use clinically irrelevant. 13
• In the setting of a permanent catheter, urinary drainage bypasses the prostatic urethra, so finasteride’s primary benefits—symptom improvement, increased flow rate, and prevention of retention—cannot be realized; consequently, no measurable “symptoms” remain for finasteride to address. 13

Practical Decision Algorithm

• Immediate discontinuation: If the catheter is confirmed to be chronic (intended for long‑term use) and the patient is not a surgical candidate or has declined surgery, finasteride should be stopped without delay. 13
• Documentation & counseling: Clinicians should document the rationale for stopping finasteride and inform the patient that the medication provides no benefit while the catheter remains in place. 13

Avoidance of Unnecessary Medication Burden

• Continuing finasteride “just in case” of future catheter removal is unwarranted because the drug requires 3–6 months to achieve meaningful prostate volume reduction, and patients on chronic catheters have already demonstrated failure of medical management. 13
• If a planned trial without catheter is anticipated, finasteride may be restarted at that time; otherwise, maintaining the drug exposes the patient to avoidable side effects (e.g., sexual dysfunction) without evidence of benefit. 13