What is the difference between avanafil and sildenafil in treating erectile dysfunction in adult males?

Avanafil vs. Sildenafil for Erectile Dysfunction

Key Distinguishing Feature

Avanafil's primary advantage over sildenafil is its significantly faster onset of action—achieving efficacy within 15 minutes compared to sildenafil's 60-minute window—allowing for greater sexual spontaneity. 1, 2, 3

Onset of Action and Timing

• Avanafil works within 15 minutes of dosing, with 64-71% successful intercourse attempts achieved in this rapid timeframe compared to 27% with placebo 1
• Sildenafil requires approximately 60 minutes before sexual activity for optimal effectiveness 4
• This faster onset makes avanafil particularly advantageous for men who value spontaneity and dislike the need to plan sexual activity an hour in advance 2, 3

Duration of Action

• Avanafil maintains efficacy for >6 hours post-dosing 1
• Sildenafil has a similar duration of action, requiring at least 24 hours before emergency nitrate administration 5, 4
• Both medications are shorter-acting than tadalafil (36 hours), making them preferable when emergency nitrate use might be needed 5

Adverse Effect Profiles

Avanafil's Superior Tolerability

• Avanafil has the lowest rates of dyspepsia among all PDE5 inhibitors 1
• Avanafil demonstrates significantly lower rates of hemodynamic side effects compared with sildenafil 6
• Avanafil has lower rates of myalgia compared to other PDE5 inhibitors 1
• Common adverse events include headache, flushing, nasal congestion, nasopharyngitis, and back pain 1

Sildenafil's Side Effect Profile

• Sildenafil commonly causes headache, flushing, dyspepsia, nasal congestion, and abnormal vision 4
• Sildenafil can alter color perception due to phosphodiesterase-6 inhibition, a rare side effect that does not occur with avanafil 7
• These effects are typically transient and mild-to-moderate 4

Efficacy Comparison

• Both medications demonstrate similar overall efficacy rates in the general ED population, with approximately 69% successful intercourse attempts versus 33% with placebo 5, 1
• Sildenafil shows 73-88% improvement in erections versus 26-32% with placebo 4
• Both remain effective across various etiologies, including diabetes, cardiovascular disease, and post-prostatectomy, though response rates may be lower in these populations 5, 1, 4

Dosing Strategies

Avanafil Dosing

• Available in 50 mg, 100 mg, and 200 mg doses, all showing similar efficacy to other PDE5 inhibitors 1
• Avanafil 200 mg is the maximum dose for optimal efficacy 1
• Use with caution at lower doses initially in patients with mild to moderate hepatic or renal impairment 1

Sildenafil Dosing

• Starting dose is 50 mg, with titration to 100 mg (maximum) or reduction to 25 mg based on efficacy and tolerability 4
• Sildenafil demonstrates dose-dependent improvement (50 mg superior to 25 mg) 4
• Lower starting dose of 25 mg required for severe hepatic/renal impairment or concurrent CYP3A4 inhibitor use 4

Critical Safety Considerations (Identical for Both)

• Both are absolutely contraindicated with any form of nitrate use due to potentially fatal hypotension 5, 1, 4
• Wait at least 24 hours after sildenafil before administering nitrates in emergency situations 5, 4
• Cardiovascular risk assessment is mandatory before prescribing either medication—patients should be able to walk 1 mile in 20 minutes or climb 2 flights of stairs without symptoms 5, 1
• Sexual stimulation is required for both medications to work—this is a common cause of apparent treatment failure 5, 1, 4

When to Choose Avanafil Over Sildenafil

Choose avanafil when:

• The patient prioritizes sexual spontaneity and wants the shortest possible waiting time before sexual activity 2, 3
• The patient has experienced significant dyspepsia or visual disturbances with sildenafil 1, 7, 6
• The patient desires a medication with lower hemodynamic side effects 6

When to Choose Sildenafil Over Avanafil

Choose sildenafil when:

• Cost is a primary concern—sildenafil has been available longer and has generic formulations 4
• The patient prefers scheduled sexual activity with a predictable 60-minute window 5
• There is extensive clinical experience and comfort with the medication 4

Common Pitfalls to Avoid (Both Medications)

• Declaring treatment failure without completing at least 5 separate attempts at maximum dose with proper technique 5, 4
• Failing to educate patients that sexual stimulation is mandatory for effectiveness 5, 1, 4
• Not addressing modifiable factors including heavy alcohol use, large meals, inadequate sexual stimulation, and relationship issues 5, 4
• Forgetting to screen for testosterone deficiency—combining PDE5 inhibitors with testosterone therapy may be more effective than either alone in hypogonadal men 5, 1, 4

Special Population Considerations

• Men with diabetes or post-prostatectomy have more severe baseline ED and may respond less robustly to both medications, though both remain effective 5, 1, 4
• In testosterone-deficient men, combining either medication with testosterone therapy is more effective than PDE5 inhibitor monotherapy 5, 1, 4