What is the recommended dosage and usage of tadalafil (Phosphodiesterase type 5 (PDE5) inhibitor) for erectile dysfunction (ED) and benign prostatic hyperplasia (BPH)?

Tadalafil Dosage and Usage for Erectile Dysfunction and Benign Prostatic Hyperplasia

For erectile dysfunction, tadalafil should be started at 10 mg as needed (up to 20 mg) or 2.5-5 mg daily; for BPH, 5 mg daily is the recommended dose. 1

Tadalafil for Erectile Dysfunction (ED)

As-Needed Dosing

• Starting dose: 10 mg taken prior to anticipated sexual activity 1
• Dose adjustment: May be increased to 20 mg or decreased to 5 mg based on individual efficacy and tolerability 1
• Maximum frequency: Once per day 1
• Timing: Can be effective up to 36 hours following dosing 1
• Food interactions: May be taken without regard to food 1

Once-Daily Dosing for ED

• Starting dose: 2.5 mg taken at approximately the same time every day 1
• Dose adjustment: May be increased to 5 mg based on individual efficacy and tolerability 1
• Timing: Take without regard to timing of sexual activity 1

Tadalafil for Benign Prostatic Hyperplasia (BPH)

• Recommended dose: 5 mg once daily, taken at approximately the same time every day 1
• Combination therapy: When used with finasteride, 5 mg daily for up to 26 weeks 1
• Efficacy: The American Urological Association recommends 5 mg daily tadalafil as a treatment option for LUTS/BPH 2

Tadalafil for Combined ED and BPH

• Recommended dose: 5 mg once daily, taken at approximately the same time every day 1
• Timing: Without regard to timing of sexual activity 1

Efficacy

• Tadalafil significantly improves erectile function compared to placebo, with approximately 69% successful sexual intercourse attempts versus 33% for placebo 2
• For BPH, tadalafil 5 mg daily shows significant improvement in International Prostate Symptom Score (IPSS) compared to placebo 2, 3
• Improvements in BPH symptoms are maintained with continued treatment over a 1-year period 3
• Tadalafil also improves ejaculatory function and sexual satisfaction in men with LUTS/BPH and ED 4

Special Populations and Considerations

Renal Impairment

• Creatinine clearance 30-50 mL/min:
  • For as-needed use: Start at 5 mg, maximum 10 mg not more than once every 48 hours 1
  • For once-daily use for BPH or ED/BPH: Start at 2.5 mg, may increase to 5 mg based on response 1
• Creatinine clearance <30 mL/min or on hemodialysis:
  • For as-needed use: Maximum 5 mg not more than once every 72 hours 1
  • For once-daily use: Not recommended 1

Hepatic Impairment

• Mild to moderate impairment (Child-Pugh Class A or B):
  • For as-needed use: Should not exceed 10 mg once per day 1
  • For once-daily use: Use with caution 1
• Severe impairment (Child-Pugh Class C): Not recommended 1

Drug Interactions

• Nitrates: Concomitant use is absolutely contraindicated due to risk of severe hypotension 1
• Alpha-blockers:
  • Patients should be stable on alpha-blocker therapy before starting tadalafil 1
  • Combination of tadalafil with alpha blockers for LUTS/BPH offers no advantages in symptom improvement over either agent alone 2

Safety and Tolerability

• Common side effects include headache (15.8%), dyspepsia (11.8%), nasopharyngitis (11.4%), and back pain (8.2%) 5
• Long-term studies show tadalafil is safe and well-tolerated for up to 24 months 5
• Discontinuation rate due to adverse events is approximately 6.3% in long-term studies 5

Clinical Pearls

• Do not split tadalafil tablets; the entire dose should be taken 1
• Tadalafil's long half-life (17.5 hours) enables once-daily dosing, which may be preferred by some patients 6
• For patients with both ED and BPH, the 5 mg daily dose effectively treats both conditions simultaneously 3
• Tadalafil may improve endothelial function in patients with BPH, potentially offering cardiovascular benefits 7

Remember that tadalafil is contraindicated with nitrates, and caution should be exercised when used with alpha-blockers due to potential hypotension. Always assess cardiovascular risk before initiating treatment.