What is the efficacy and potential for serious side effects of Avanafil (phosphodiesterase type 5 inhibitor) 200 mg tablets used as needed for erectile dysfunction?

Avanafil 200 mg: Efficacy and Safety Profile

Yes, avanafil 200 mg works effectively for erectile dysfunction and is generally well-tolerated, with most side effects being mild to moderate and transient. 1, 2

Efficacy of Avanafil 200 mg

Avanafil 200 mg demonstrates statistically significant and clinically meaningful improvements in erectile function across multiple validated measures. 2, 3

• In randomized controlled trials, avanafil 200 mg significantly improved International Index of Erectile Function-Erectile Function Domain (IIEF-EFD) scores compared to placebo 2, 3
• Successful vaginal penetration rates (SEP2) improved with an odds ratio of 5.06 (95% CI: 3.29-7.78) 4
• Successful intercourse completion rates (SEP3) improved with an odds ratio of 3.99 (95% CI: 2.80-5.67) 4
• Approximately two-thirds of sexual intercourse attempts were successful when taken 15 minutes before or more than 6 hours after administration, compared to only one-quarter with placebo 2
• The 200 mg dose can be taken as early as 15 minutes before sexual activity, with rapid absorption occurring at a median time to maximum concentration of 30-45 minutes 1, 2

Sexual stimulation is required for the medication to work—this is a critical point for patient education. 1

Safety Profile and Common Side Effects

Avanafil is generally well-tolerated with a favorable safety profile, and serious adverse events are rare. 2, 5

Most Common Side Effects (Mild to Moderate):

• Headache (most common) 6, 1, 7
• Flushing 6, 1, 3
• Nasal congestion or stuffy/runny nose 6, 1, 7
• Nasopharyngitis and sore throat 6, 1
• Back pain 6, 1

Notably, avanafil has the lowest rates of dyspepsia among all PDE5 inhibitors and similarly low rates of myalgia compared to other agents in this class. 6, 8

Discontinuation Rates:

• Only ≤2% of patients discontinued treatment due to adverse events in pooled clinical trial analysis 2
• During extended treatment exceeding 52 weeks, only 2.8% discontinued due to adverse reactions with no drug-related serious adverse events 2
• The dropout rate due to adverse events was not significantly different from placebo (OR = 1.48,95% CI: 0.54-4.08) 4

Serious Side Effects (Rare but Important)

While rare, several serious adverse effects require immediate medical attention and patient counseling:

Priapism:

• Erections lasting more than 4 hours require immediate medical attention to prevent permanent penile damage 1

Sudden Vision Loss:

• Non-arteritic anterior ischemic optic neuropathy (NAION) has been reported with PDE5 inhibitors, though causality remains uncertain 9, 1
• Patients should stop the medication immediately and seek medical care if sudden vision loss occurs in one or both eyes 1

Sudden Hearing Loss:

• Sudden decrease or loss of hearing, potentially with tinnitus or dizziness, has been reported 1
• Discontinue medication and seek medical evaluation if this occurs 1

Cardiovascular Considerations:

• The most critical safety concern is the absolute contraindication with nitrate use due to potentially life-threatening hypotension 1
• At least 12 hours must elapse after the last avanafil dose before nitrate administration can be considered in life-threatening situations 1

Absolute Contraindications

Do not prescribe avanafil 200 mg in the following situations:

• Concurrent nitrate use in any form (absolute contraindication) 1
• Strong CYP3A4 inhibitors (ketoconazole, ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, saquinavir, telithromycin) 1
• Known hypersensitivity to avanafil or any tablet component 1

High-Risk Cardiac Patients Requiring Stabilization First:

• Unstable or refractory angina 8
• Uncontrolled hypertension 8
• Left ventricular dysfunction/CHF (NYHA class II or greater) 8
• MI or CVA within previous 2 weeks 8
• High-risk arrhythmias 8
• Hypertrophic obstructive cardiomyopathy 8
• Moderate-to-severe valvular disease 8

Before prescribing, assess whether the patient can perform exercise equivalent to walking 1 mile in 20 minutes or climbing 2 flights of stairs in 20 seconds without symptoms—if not, refer to cardiology first. 6

Dosing Adjustments and Special Populations

• With moderate CYP3A4 inhibitors (erythromycin, diltiazem, fluconazole, verapamil), maximum dose is 50 mg, not exceeding once every 24 hours 1
• When co-administered with alpha-blockers, start at 50 mg only after the patient is stable on alpha-blocker therapy 1
• Use with caution at lower initial doses in mild to moderate hepatic or renal impairment 6
• Maximum dosing frequency is once per day 1
• Can be taken with or without food 1

Optimizing Treatment Success

Proper patient education is essential, as incorrect use accounts for many treatment failures. 6, 10

• Emphasize that sexual stimulation is necessary for the medication to work 6
• Dose titration should be performed to balance efficacy and minimize adverse effects 6, 10
• The lowest effective dose should be used 1
• Avoid excessive alcohol consumption (more than 3 glasses of wine or 3 shots of whiskey), which can increase heart rate, lower blood pressure, cause dizziness, or worsen headaches 1

Special Population Considerations

• Men with diabetes have more severe ED at baseline and may respond less robustly, potentially requiring the higher 200 mg dose 6, 8
• Post-prostatectomy patients similarly have more severe ED and may need higher dosing 6, 8
• Combining testosterone therapy with avanafil may improve efficacy in men with both ED and testosterone deficiency 6