What is the recommended dosage of tadalafil (phosphodiesterase type 5 inhibitor) for various medical conditions?

Tadalafil Dosage Recommendations for Various Medical Conditions

For erectile dysfunction (ED), tadalafil is recommended at 10 mg as needed prior to sexual activity, with adjustments to 5-20 mg based on efficacy and tolerability, or at 2.5-5 mg for once-daily dosing. For pulmonary hypertension, tadalafil is dosed at 40 mg once daily, while for benign prostatic hyperplasia (BPH), 5 mg once daily is recommended 1.

Erectile Dysfunction Dosing

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 response and side effects 1
• Maximum frequency: Once per day in most patients 1
• Duration of effect: Up to 36 hours following dosing 1, 2

Once-Daily Dosing

• 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
• Benefit: Provides spontaneous rather than scheduled sexual activity 3
• Evidence: Daily use of 2.5 mg and 5 mg for 12 weeks was well tolerated and significantly improved erectile dysfunction in diabetic men 3

Pulmonary Hypertension Dosing

• Recommended dose: 40 mg once daily 3
• Efficacy: Tadalafil has shown favorable results on exercise capacity, symptoms, hemodynamics, and time to clinical worsening 3
• Contraindication: The combination of tadalafil with other PDE5 inhibitors or riociguat is contraindicated due to hypotension risk 3

Pediatric Pulmonary Hypertension Dosing

• Starting dose: 0.5-1 mg/kg/day 3
• Maximum dose: 40 mg once daily 3
• Age restriction: Only evaluated in children >3 years of age 3
• Safety considerations: Limited safety and efficacy data in children 3

Benign Prostatic Hyperplasia Dosing

• Recommended dose: 5 mg once daily, taken at approximately the same time every day 1
• Combination therapy: When used with finasteride, 5 mg once daily for up to 26 weeks 1

Combined ED and BPH Treatment

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

Special Population Considerations

Renal Impairment

• Moderate impairment (CrCl 30-50 mL/min):
  • As-needed: Start with 5 mg, maximum 10 mg every 48 hours 1
  • Once-daily for BPH/ED: Start with 2.5 mg, may increase to 5 mg based on response 1
• Severe impairment (CrCl <30 mL/min):
  • As-needed: Maximum 5 mg every 72 hours 1
  • Once-daily: Not recommended 1

Hepatic Impairment

• Mild to moderate impairment:
  • As-needed: Should not exceed 10 mg once per day 1
  • Once-daily: Use with caution 1
• Severe impairment: Not recommended 1

Drug Interactions

• Nitrates: Contraindicated due to risk of severe hypotension 3, 1
• CYP3A4 inhibitors:
  • As-needed: Limit to 10 mg no more than once every 72 hours 1
  • Once-daily: Maximum dose 2.5 mg 1
• Alcohol: Caution advised as both act as mild vasodilators 1

Clinical Pearls

• Tadalafil may be taken without regard to food 1
• The long half-life (17.5 hours) of tadalafil enables once-daily dosing 4
• Once-daily dosing allows for spontaneous rather than scheduled sexual activity 3, 5
• For ED patients who had an incomplete response to as-needed PDE5 inhibitors, switching to once-daily tadalafil (5 mg) resulted in 40% of patients returning to normal erectile function 6
• Most patients take advantage of tadalafil's 36-hour duration of action, with many attempting intercourse 12-36 hours after dosing 2

Common Side Effects

• Headache, flushing, dyspepsia, nasal congestion, back pain, myalgia 7, 1
• Side effects are generally mild to moderate and dose-dependent 7

Always assess cardiovascular risk before initiating treatment, as patients at high risk should be stabilized by cardiological treatment before sexual activity or ED treatment is recommended 3.