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 for Erectile Dysfunction and Benign Prostatic Hyperplasia

For erectile dysfunction, start with tadalafil 10 mg as needed (taken prior to sexual activity) or 2.5 mg daily, titrating based on response and tolerability; for BPH or combined ED/BPH, use tadalafil 5 mg once daily. 1, 2

Erectile Dysfunction Dosing

As-Needed Dosing

• Start with 10 mg taken prior to anticipated sexual activity 2
• Titrate to 20 mg for improved efficacy or decrease to 5 mg if tolerability is an issue 1, 2
• Maximum dosing frequency is once per day 2
• Tadalafil remains effective up to 36 hours after dosing, which should be discussed with patients 2
• Critical: Unlike sildenafil and vardenafil, tadalafil does NOT show dose-dependent improvement between 5-20 mg doses—choose between 10 mg and 20 mg based primarily on tolerability rather than expecting dramatically better efficacy 3

Daily Dosing

• Start with 2.5 mg taken at approximately the same time every day 2
• May increase to 5 mg daily based on efficacy and tolerability 2, 4
• Daily dosing eliminates the need to time medication with sexual activity, providing an option for couples who prefer spontaneous rather than scheduled intimacy 3
• Both 2.5 mg and 5 mg daily dosing are effective, with similar efficacy to as-needed dosing 4

Benign Prostatic Hyperplasia Dosing

• Use 5 mg once daily, taken at approximately the same time every day 1, 2
• This is the only FDA-approved dose for BPH 2
• When initiating combination therapy with finasteride for BPH, use tadalafil 5 mg daily for up to 26 weeks 2
• Tadalafil 5 mg provides modest but statistically significant improvement in International Prostate Symptom Score (mean change -5.4 points vs -3.6 points with placebo) 1
• Tadalafil is most appropriate for men with concomitant erectile dysfunction; the benefit for BPH alone is modest 1

Combined ED and BPH

• Use 5 mg once daily without regard to timing of sexual activity 2, 5
• This single dose treats both conditions simultaneously 3, 6, 5
• Tadalafil 5 mg significantly improved both erectile function (IIEF-EF domain) and BPH symptoms (IPSS) in men with both conditions 5

Special Population Dosing Adjustments

Renal Impairment

As-needed dosing: 2

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

Daily dosing for ED: 2

• CrCl <30 mL/min or hemodialysis: Not recommended

Daily dosing for BPH or ED/BPH: 2

• CrCl 30-50 mL/min: Start with 2.5 mg daily, may increase to 5 mg based on response
• CrCl <30 mL/min or hemodialysis: Not recommended

Hepatic Impairment

As-needed dosing: 2

• Mild to moderate (Child-Pugh A or B): Maximum 10 mg once daily
• Severe (Child-Pugh C): Not recommended

Daily dosing: 2

• Mild to moderate (Child-Pugh A or B): Use with caution (not extensively studied)
• Severe (Child-Pugh C): Not recommended

Critical Safety Considerations

Absolute Contraindications

• Tadalafil is absolutely contraindicated with any form of nitrate use due to risk of potentially fatal hypotension 3, 2
• Patients must be explicitly asked about all forms of nitrate use before prescribing 3

Cardiovascular Risk Assessment

• Before prescribing, assess the patient's ability to perform moderate physical activity 3
• Low-risk patients (asymptomatic CAD with <3 risk factors, controlled hypertension, mild stable angina, successful revascularization, uncomplicated past MI, mild valvular disease, CHF NYHA class I) can safely receive tadalafil 3
• Patients whose cardiovascular risk is indeterminate or who cannot perform moderate physical activity should be referred to cardiology before prescribing 3

Emergency Nitrate Protocol

• If emergency nitrates are needed: wait 24 hours after sildenafil, 48 hours after tadalafil before administering nitrates under close medical supervision 3

Combination Therapy Considerations

Alpha-Blockers

• Do NOT combine tadalafil 5 mg daily with alpha-blockers for LUTS/BPH—it offers no advantage over either agent alone 1
• However, research suggests combination therapy is safe without clinically significant hypotensive events 7
• If both are needed, consider using as-needed tadalafil for ED while continuing alpha-blocker for BPH 3

Testosterone Therapy

• For men with both ED and testosterone deficiency, combining tadalafil with testosterone therapy may be more effective than tadalafil alone 3
• Testosterone therapy alone is not effective monotherapy for ED 3

Maximizing Treatment Success

Patient Instructions

• Sexual stimulation is necessary for tadalafil to be effective—this is a common cause of treatment failure 3
• Tadalafil may be taken without regard to food 2
• Do not split tablets; take the entire dose 2
• An adequate trial consists of at least 5 separate attempts at maximum dose before declaring treatment failure 3

Before Declaring Treatment Failure

Evaluate whether the trial was adequate by addressing: 3

• Hormonal abnormalities (particularly testosterone deficiency)
• Food or drug interactions
• Timing and frequency of dosing
• Adequacy of sexual stimulation
• Heavy alcohol use
• Relationship issues with partner

Dose Titration

• Titrate doses to find the optimal balance between efficacy and side effects 1, 3
• If the first PDE5 inhibitor fails after an adequate trial, consider switching to a different agent 3

Common Adverse Events

• Most frequent: dyspepsia, headache, back pain, nasal congestion, myalgia 1
• Tadalafil has lower rates of flushing compared to other PDE5 inhibitors 1, 3
• Adverse events follow a dose-response pattern 1
• Most adverse events are mild to moderate in intensity 6

Special Populations Response

• Men with diabetes and men who are post-prostatectomy have more severe ED at baseline and respond less robustly to all PDE5 inhibitors, including tadalafil 1, 3
• These patients may require higher doses or combination therapy with testosterone (if deficient) 3

Ongoing Management

Periodic follow-up should assess: 3

• Efficacy and side effects
• Verification that cardiovascular health hasn't changed
• Review of new medications (particularly nitrates)
• Assessment of treatment effectiveness
• Evaluation of side effects