What is the recommended dosing for tadalafil (Cialis)?

Tadalafil Dosing Recommendations

Erectile Dysfunction

For erectile dysfunction, start with tadalafil 10 mg taken as needed prior to sexual activity, with dose adjustment to 20 mg (maximum) or 5 mg (minimum) based on efficacy and tolerability. 1

As-Needed Dosing (PRN)

• Starting dose: 10 mg taken prior to anticipated sexual activity 1
• Dose range: 5-20 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, allowing flexibility in timing of sexual activity 1
• Tadalafil may be taken without regard to food 1

Once-Daily Dosing

• Starting dose: 2.5 mg taken at approximately the same time every day 1
• Maximum dose: 5 mg once daily based on efficacy and tolerability 1
• Taken without regard to timing of sexual activity 1
• This regimen eliminates the need to plan sexual activity within a specific timeframe 2, 3

Important Dosing Considerations

• Unlike sildenafil, tadalafil does NOT demonstrate clear dose-related improvements in erectile function, meaning higher doses may not provide additional benefit 4
• Sexual stimulation is necessary for tadalafil to be effective 4
• More than one trial may be required to establish efficacy; an adequate trial is defined as at least 5 separate occasions at the maximum dose 5
• Titration should be based on finding the dose that meets treatment expectations without unacceptable adverse effects 4

Benign Prostatic Hyperplasia (BPH)

For BPH, use tadalafil 5 mg once daily taken at approximately the same time every day. 1

• Fixed dose: 5 mg once daily (no titration needed) 1
• When initiating therapy with both tadalafil and finasteride, use 5 mg once daily for up to 26 weeks 1

Combined Erectile Dysfunction and BPH

For patients with both ED and BPH, use tadalafil 5 mg once daily without regard to timing of sexual activity. 1

Special Populations

Renal Impairment

As-Needed Dosing:

• CrCl 30-50 mL/min: Start with 5 mg, maximum 10 mg once every 48 hours 1
• CrCl <30 mL/min or hemodialysis: Maximum 5 mg once every 72 hours 1

Once-Daily Dosing:

• CrCl 30-50 mL/min (BPH or ED/BPH): Start with 2.5 mg once daily, may increase to 5 mg based on response 1
• CrCl <30 mL/min or hemodialysis: Once-daily dosing is NOT recommended for any indication 1

Hepatic Impairment

As-Needed Dosing:

• Mild to moderate (Child-Pugh A or B): Maximum dose 10 mg once per day 1
• Severe (Child-Pugh C): Tadalafil is NOT recommended 1

Once-Daily Dosing:

• Mild to moderate hepatic impairment: Use with caution; not extensively evaluated 1
• Severe hepatic impairment: Tadalafil is NOT recommended 1

Drug Interactions with CYP3A4 Inhibitors

When taking potent CYP3A4 inhibitors (ritonavir, ketoconazole, itraconazole):

• As-needed dosing: Maximum 10 mg once every 72 hours 1
• Once-daily dosing: Maximum 2.5 mg daily 1

Critical Safety Considerations

Absolute Contraindications

• Nitrate medications are absolutely contraindicated with tadalafil due to severe hypotension risk 4, 5
• Avoid nitrates for at least 48 hours after tadalafil use (longer than the 24-hour restriction for sildenafil/vardenafil) 4, 5

Cardiovascular Risk Assessment

• Assess cardiovascular risk before prescribing, particularly in patients unable to perform moderate exercise (walking 1 mile in 20 minutes or climbing 2 flights of stairs in 20 seconds) 4, 5

Common Adverse Effects

• Most frequent: Headache, dyspepsia, back pain, flushing, nasal congestion, and myalgia 4, 6
• Most adverse events are transient and mild to moderate in severity 4
• Discontinuation rate due to adverse events: 6.3% in long-term studies 6

Alcohol Interaction

• Substantial alcohol consumption (≥5 units) combined with tadalafil can increase orthostatic symptoms including dizziness, increased heart rate, and decreased standing blood pressure 1

Pulmonary Arterial Hypertension

For PAH, tadalafil 40 mg once daily has been shown effective in improving exercise capacity, symptoms, hemodynamics, and time to clinical worsening 7

• The side-effect profile in PAH patients is similar to that seen in ED patients 7
• This indication uses a higher dose than ED or BPH 7

Common Pitfalls to Avoid

• Do not split tadalafil tablets; the entire dose should be taken 1
• Do not combine tadalafil with other PDE5 inhibitors or other ED treatments 1
• Do not assume higher doses are always better; tadalafil lacks clear dose-response relationship unlike sildenafil 4
• Do not forget to counsel patients that sexual stimulation is required for effectiveness 4, 5