Avanafil (Stendra): How It Compares to Viagra, Cialis, Levitra, and Alprostadil

What Is Avanafil and How Does It Work?

Avanafil is a selective PDE5 inhibitor approved by the FDA in April 2012 under the brand name Stendra. Like sildenafil, tadalafil, and vardenafil, it blocks the enzyme phosphodiesterase type 5, which allows cyclic GMP to accumulate in penile smooth muscle, relaxing arterial walls and increasing blood flow during sexual stimulation. Without that stimulation, the drug does nothing. Erection still requires arousal.

What sets avanafil apart is its selectivity profile. It has a higher ratio of PDE5 inhibition to PDE6 inhibition than sildenafil, which may explain why fewer men report visual disturbances such as color-tinge or blurred vision. A 2012 pooled phase-III analysis published on PubMed (Goldstein et al.) showed that visual adverse events occurred in roughly 1% of avanafil-treated men vs. 3 to 11% with sildenafil at comparable therapeutic doses.

The drug is metabolized primarily by CYP3A4 in the liver, with a half-life of approximately 5 hours. That aligns with its clinical duration of up to 6 hours, shorter than tadalafil's 17.5-hour half-life but similar to sildenafil and vardenafil.

Avanafil Dosing: What the FDA Label Says

The starting dose is 100 mg, taken approximately 30 minutes before sexual activity. Physicians may adjust down to 50 mg if tolerance is a concern, or up to 200 mg if the 100 mg dose is insufficient. The maximum recommended frequency is once per day.

One practical advantage: avanafil can be taken with or without food, including a high-fat meal. The FDA prescribing information confirms that a high-fat meal delayed the Tmax of sildenafil by approximately 60 minutes and reduced its Cmax by 29%, while avanafil pharmacokinetics were not meaningfully affected by food. That matters for men who want to take a pill at dinner without watching a clock.

Dose adjustments are required when avanafil is co-administered with moderate CYP3A4 inhibitors such as erythromycin or fluconazole; the maximum dose in that context drops to 100 mg per 24 hours. Strong CYP3A4 inhibitors (ketoconazole, ritonavir) are contraindicated alongside avanafil.

Onset Speed: The 15-Minute Data

Speed of onset is avanafil's most cited clinical feature. In a double-blind, placebo-controlled trial (N=646) published in the Journal of Sexual Medicine, 64% of avanafil 200 mg attempts that began within 15 minutes of dosing resulted in successful vaginal penetration, compared with 27% in the placebo group. That trial, available on PubMed, is the primary reference for the "works in 15 minutes" claim.

Sildenafil's label recommends taking the drug 30 to 60 minutes before sex, with absorption further delayed by food. Vardenafil's prescribing information recommends 60 minutes. Tadalafil taken as needed also recommends 30 minutes but its long half-life means timing is less strict in practice.

The 15-minute onset figure applies to the 200 mg dose under ideal conditions. At 100 mg, the median onset in trials was closer to 20 to 30 minutes. Men who want reliable spontaneity at the 15-minute mark will generally need the 200 mg dose.

Avanafil vs. Sildenafil (Viagra): Key Differences

Sildenafil was the first oral PDE5 inhibitor approved by the FDA, cleared in March 1998, and it remains the most prescribed ED drug worldwide. Generic sildenafil has been available in the US since 2017, which makes it far cheaper than brand-name Stendra.

The core pharmacological differences are speed and selectivity. A head-to-head crossover study (N=172) published in the International Journal of Impotence Research found that avanafil 200 mg produced a statistically significant faster onset than sildenafil 100 mg, with a median time to erection onset of 10 minutes vs. 27 minutes on penile plethysmography.

Side-effect profiles overlap substantially. Both drugs can cause headache, flushing, nasal congestion, and dyspepsia. Sildenafil causes more blue-tinge visual disturbances due to weaker PDE6 selectivity. Avanafil shows a lower incidence of that specific side effect but shares the same absolute contraindication: concurrent use with any organic nitrate, including nitroglycerin, isosorbide mononitrate, or amyl nitrite. Combined use can cause a precipitous drop in blood pressure.

Cost is decisive for many patients. Generic sildenafil can be obtained for as low as $1, 4 per tablet through telehealth pharmacies or GoodRx pricing, while brand Stendra often runs $40, 80 per tablet without insurance.

Avanafil vs. Tadalafil (Cialis): Key Differences

Tadalafil is the only PDE5 inhibitor available in a once-daily low-dose formulation. At 2.5 mg or 5 mg daily, it maintains a steady-state plasma level that allows erections without timing a dose to sexual activity. That option does not currently exist with avanafil.

The CIALIS key trial program, summarized in FDA labeling, showed that tadalafil 5 mg once daily produced statistically significant improvements in IIEF-EF domain scores vs. placebo over 12 weeks (P<0.001), with 75% of intercourse attempts successful vs. 47% with placebo.

Tadalafil's 17.5-hour half-life translates into a 36-hour window of effect, earning it the nickname "the weekend pill." Men who prefer not to plan around a dose often choose tadalafil. Avanafil's 6-hour window is shorter, which some men see as a benefit because side effects also resolve faster.

Both drugs are metabolized by CYP3A4. Tadalafil inhibits PDE11A at clinically relevant concentrations, which may explain occasional reports of back pain and myalgia that appear less frequently with avanafil. A pooled safety analysis available through PubMed confirms back pain rates of approximately 3.5% with tadalafil vs. under 1% with avanafil.

Generic tadalafil is widely available in the US and costs $2, 10 per tablet at most pharmacies, reinforcing a cost advantage over Stendra.

Avanafil vs. Vardenafil (Levitra / Staxyn): Key Differences

Vardenafil (Levitra, Staxyn) was approved by the FDA in August 2003. It shares a chemical structure closer to sildenafil than to tadalafil, and its clinical duration is approximately 4 to 6 hours, similar to avanafil.

Vardenafil is available as a standard film-coated tablet (Levitra) and as an orally disintegrating tablet (Staxyn, 10 mg), which dissolves on the tongue without water. That formulation can be appealing when discretion or convenience matters. Avanafil has no equivalent orally disintegrating form.

One clinical consideration: vardenafil produces a small but measurable QTc prolongation in cardiac electrophysiology studies. The FDA label for vardenafil includes a warning about QT prolongation and notes that it should not be used with Class IA antiarrhythmics (quinidine, procainamide) or Class III antiarrhythmics (amiodarone, sotalol). Avanafil does not carry the same degree of QT-prolongation concern, which may make it preferable for men on antiarrhythmic therapy (pending physician review of their full medication list).

Onset for vardenafil is typically 30 to 60 minutes, similar to sildenafil. Avanafil's speed advantage over vardenafil mirrors its advantage over sildenafil.

Generic vardenafil is available in the US, providing a cost-competitive option for men who respond well to it.

Avanafil vs. Alprostadil (MUSE, Caverject, Edex): A Different Mechanism

Alprostadil is not a PDE5 inhibitor. It is a synthetic form of prostaglandin E1 that directly relaxes smooth muscle in the corpus cavernosum, bypassing the nitric oxide pathway entirely. It is available as an intraurethral suppository (MUSE), an intracavernosal injection (Caverject, Edex), or a topical cream (Vitaros, approved in Canada and the EU but not the US as of mid-2025).

A landmark crossover trial (N=296) published in the New England Journal of Medicine found that intracavernosal alprostadil produced erections sufficient for intercourse in 87% of men with ED, including men who had failed oral PDE5 inhibitors.

The clinical population for alprostadil differs from that for avanafil. Alprostadil works in men with significant nerve damage or vascular disease who do not respond to oral agents, including post-prostatectomy patients and those with severe diabetes-related ED. Avanafil, like all PDE5 inhibitors, requires at least partial nitric oxide signaling to be effective.

Side effects are substantially different. Alprostadil injections and suppositories frequently cause penile pain (reported in 30 to 37% of men using MUSE in clinical trials), urethral burning, and, rarely, prolonged erections (priapism). Avanafil's side effects, primarily headache (8.9%), flushing (6.4%), and nasal congestion (2.1%), are generally milder and transient.

Men who cannot use nitrates but also cannot achieve adequate erections with any PDE5 inhibitor are the primary candidates for alprostadil. For most men with mild-to-moderate vasculogenic or psychogenic ED, oral avanafil is tried before alprostadil.

Side Effects and Safety Profile of Avanafil

The most common adverse effects reported in avanafil phase-III trials were headache (8.9% at 200 mg vs. 1.9% placebo), flushing (6.4% vs. 1.0%), nasal congestion (2.1% vs. 0.5%), and nasopharyngitis (1.4% vs. 1.3%). These figures come from the pooled phase-III data available on PubMed.

Serious cardiovascular events were rare and occurred at rates similar to placebo in trials. All PDE5 inhibitors potentiate the hypotensive effects of nitrates, and that combination is absolutely contraindicated. Men taking alpha-blockers for benign prostatic hyperplasia should start avanafil at the 50 mg dose to avoid additive hypotension.

Avanafil is contraindicated in patients with severe hepatic impairment (Child-Pugh class C), as hepatic metabolism is the primary clearance route. Dose adjustment is not required for mild-to-moderate renal impairment, but men with eGFR <30 mL/min should be monitored carefully.

The American Urological Association's 2018 Erectile Dysfunction guideline states: "All currently approved PDE5 inhibitors are considered first-line treatment for erectile dysfunction in men who are appropriate candidates and who do not have contraindications to the drug class." See the AUA guideline summary here.

Who Is Avanafil Best Suited For?

Avanafil fits best in a specific clinical profile. Men who want the fastest possible onset, who find sildenafil's food restrictions inconvenient, or who experience visual side effects with sildenafil are the most logical candidates.

The following decision framework reflects the HealthRX clinical team's approach when selecting a PDE5 inhibitor for a new patient:

1. Frequency of sexual activity. Men who have sex more than twice per week often do better on tadalafil 5 mg daily, which avoids the need to take a pill before each encounter.
2. Onset urgency. Men who want the shortest possible window between dosing and activity are best served by avanafil 200 mg.
3. Food and alcohol habits. Men who regularly eat high-fat meals before sex will find avanafil or tadalafil more predictable than sildenafil.
4. Cardiac or antiarrhythmic medications. Men on antiarrhythmic drugs that prolong QT should avoid vardenafil and discuss avanafil or tadalafil with their cardiologist.
5. Cost sensitivity. When cost is the primary constraint and the patient has no tolerance or food-interaction issues with sildenafil, generic sildenafil at $1, 4 per dose is usually the first recommendation.
6. PDE5 inhibitor failure. Men who have genuinely failed two or more PDE5 inhibitors at maximum tolerated doses should be evaluated for alprostadil, a vacuum erection device, or penile prosthesis.

The American Urological Association notes that PDE5 inhibitor "failure" is often dose-related or technique-related (taking the pill without adequate arousal, taking it too close to a meal, or not waiting long enough). A systematic retry with optimized technique recovers response in a meaningful fraction of men before escalating to second-line therapies.

Practical Prescribing Notes

Avanafil is available by prescription only in the US. Telehealth platforms, including HealthRX, can prescribe it after a clinician review of the patient's cardiovascular history, medication list, and blood pressure. The FDA label does not require a serum testosterone check before prescribing, though the AUA recommends measuring morning total testosterone in men with ED who also report low libido, fatigue, or other hypogonadal symptoms. Low testosterone affects 15 to 30% of men with ED, per data from the Massachusetts Male Aging Study.

Compounded avanafil is not currently recognized as an FDA-approved product and should not be substituted for brand Stendra without a specific clinical rationale and pharmacy-level quality verification.

Brand Stendra patient assistance programs are available through the manufacturer (Metuchen Pharmaceuticals) for men who meet income eligibility criteria. Men without insurance should ask their prescriber about GoodRx pricing before paying retail.

Frequently Asked Questions