What is the recommended dosage and usage of Tadalafil (Phosphodiesterase type 5 (PDE5) inhibitor) for treating 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 taken prior to anticipated sexual activity, with dose adjustment to 5-20 mg based on efficacy and tolerability; for BPH, tadalafil 5 mg once daily is the recommended dose. 1

Erectile Dysfunction (ED) Treatment

On-Demand 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 improve erectile function up to 36 hours following dosing 1
• Administration: Take without regard to food; do not split tablets 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 efficacy and tolerability 1
• Advantage: Allows for spontaneous sexual activity without timing constraints 2

Benign Prostatic Hyperplasia (BPH) Treatment

• Recommended dose: 5 mg once daily, taken at approximately the same time every day 1
• Efficacy: Significantly improves International Prostate Symptom Score (IPSS) compared to placebo 2
• When combined with finasteride: 5 mg once daily for up to 26 weeks 1

Combined ED and BPH Treatment

• Recommended dose: 5 mg once daily 1
• Efficacy: Significantly improves both IPSS and IIEF-EF domain scores compared to placebo 3

Special Populations and Considerations

Renal Impairment

• Moderate impairment (CrCl 30-50 mL/min):
  • For on-demand use: Start with 5 mg, maximum 10 mg every 48 hours 1
  • For once-daily use for BPH or ED/BPH: Start with 2.5 mg, may increase to 5 mg 1
• Severe impairment (CrCl <30 mL/min) or on hemodialysis:
  • For on-demand use: Maximum 5 mg every 72 hours 1
  • For once-daily use: Not recommended 1

Hepatic Impairment

• Mild to moderate impairment (Child-Pugh Class A or B):
  • For on-demand use: Maximum 10 mg once per day 1
  • For once-daily use: Use with caution 1
• Severe impairment (Child-Pugh Class C): Not recommended 1

Contraindications and Precautions

• Absolute contraindication: Concomitant use with nitrates in any form due to risk of severe hypotension 2
• Timing with nitrates if needed: Wait at least 24 hours after sildenafil and 48 hours after tadalafil before administering nitrates 4
• Use with alpha-blockers: Exercise caution due to potential hypotension 4
• Combination therapy: Tadalafil should not be used in combination with alpha blockers for BPH treatment as it offers no advantages in symptom improvement over either agent alone 2

Efficacy and Safety

• Efficacy for ED: Tadalafil significantly improves successful sexual intercourse rates (69% vs. 33% for placebo) 2
• Efficacy for BPH: Significantly improves IPSS scores compared to placebo 2, 5
• Long-term safety: Well-tolerated for up to 2 years of daily use 6
• Common side effects: Dyspepsia, headache, back pain, facial flushing, and myalgia 2, 6

Clinical Pearls

• Tadalafil has a longer half-life (17.5 hours) than other PDE5 inhibitors, making it suitable for once-daily dosing 7
• For patients with both ED and BPH, the 5 mg once-daily dose effectively treats both conditions simultaneously 3
• Daily tadalafil 5 mg appears safe when combined with alpha-blockers for BPH, with minimal hypotensive events, though this is not officially recommended 8
• Cardiovascular risk should be assessed before initiating treatment, as ED can be a marker for underlying cardiovascular disease 2

By following these dosing guidelines and considering individual patient factors, tadalafil can effectively manage both erectile dysfunction and benign prostatic hyperplasia with minimal side effects.