What is the recommended dosing and administration for tadalafil (phosphodiesterase type 5 inhibitor) in patients with erectile dysfunction?

Tadalafil Dosing and Administration for Erectile Dysfunction

For patients with erectile dysfunction, tadalafil should be prescribed at an initial dose of 10 mg taken prior to anticipated sexual activity, with dose adjustments to 5 mg or 20 mg based on individual efficacy and tolerability. 1

Dosing Options

As-Needed Dosing

• Start with 10 mg taken prior to anticipated sexual activity 1
• May increase to 20 mg or decrease to 5 mg based on efficacy and tolerability 1
• Maximum recommended dosing frequency is once per day 1
• Tadalafil improves erectile function for up to 36 hours following dosing 1, 2

Once-Daily Dosing

• Initial dose of 2.5 mg taken at approximately the same time every day 1
• May increase to 5 mg based on individual efficacy and tolerability 1
• Taken without regard to timing of sexual activity 1
• Eliminates the need to time medication with sexual activity, providing an alternative for couples who prefer spontaneous rather than scheduled sexual activity 3, 4

Special Populations

Renal Impairment

• For creatinine clearance 30-50 mL/min with as-needed dosing:
  • Start with 5 mg not more than once per day
  • Maximum dose is 10 mg not more than once every 48 hours 1
• For creatinine clearance <30 mL/min or on hemodialysis with as-needed dosing:
  • Maximum dose is 5 mg not more than once every 72 hours 1
• For creatinine clearance <30 mL/min or on hemodialysis:
  • Once-daily use is not recommended 1

Hepatic Impairment

• Mild to moderate impairment (Child-Pugh Class A or B):
  • Dose should not exceed 10 mg once per day 1
• Severe hepatic impairment:
  • Use of PDE5 inhibitors is generally not recommended 5, 1

Administration Guidelines

• Tadalafil may be taken without regard to food 1
• Do not split tablets; entire dose should be taken 1
• Sexual stimulation is necessary for tadalafil to be effective 3
• For as-needed dosing, tadalafil has shown erectogenic effect as early as 16 minutes after dosing with the 20 mg dose 2

Safety Considerations

• Tadalafil is contraindicated in patients taking nitrates due to risk of severe hypotension 5
• If a patient has taken sildenafil, wait at least 24 hours before administering nitrates; for tadalafil, wait at least 48 hours 5
• Most common adverse events include dyspepsia, headache, back pain, nasal congestion, and myalgia 5, 3, 6
• Tadalafil has lower rates of flushing compared to other PDE5 inhibitors 3
• Long-term safety studies show tadalafil is well-tolerated for extended periods (up to 24 months) 4, 6

Efficacy Considerations

• High-quality evidence shows that tadalafil significantly improves erectile function compared to placebo 3, 7
• 69% of men using tadalafil as needed report successful sexual intercourse attempts compared to 33% with placebo 3
• Men with diabetes and men who are post-prostatectomy have more severe ED at baseline and may respond less robustly to PDE5 inhibitors 5, 8
• For men with ED and testosterone deficiency, combining tadalafil with testosterone therapy may be more effective than tadalafil alone 3

Common Pitfalls to Avoid

• Failure to provide proper instructions on medication use (incorrect use accounts for many treatment failures) 5, 3
• Not titrating dose to find optimal balance between efficacy and side effects 5
• Prescribing tadalafil concurrently with nitrate medications 5
• Not recognizing that ED may be a marker for cardiovascular disease; patients with ED should be evaluated for cardiovascular risk factors 5
• Not allowing adequate time for medication effect before concluding treatment failure 5