News Author: Robert Lowes
CME Author: Laurie Barclay, MD
Avanafil is the fifth branded oral drug for erectile dysfunction (ED) approved by the US Food and Drug Administration (FDA). Like tadalafil, vardenafil, and sildenafil, avanafil is a phosphodiesterase type 5 (PDE5) inhibitor. Although this class of drugs is effective for ED by increasing blood flow to the penis, it can also cause hypotension in men taking nitrates and may cause rare, but serious, adverse events including color vision changes, a sudden loss of vision or hearing, and erections lasting more than 4 hours.
Study Synopsis and Perspective
Avanafil (Stendra), a new drug to treat ED, was approved by the FDA.
It becomes the fifth FDA-approved branded oral drug for ED. The others are tadalafil (Cialis), vardenafil (Levitra, Staxyn), and sildenafil (Viagra).
Like the others, avanafil belongs to the drug class called PDE5 inhibitors, which increase blood flow to the penis. As a PDE5 inhibitor, avanafil should not be prescribed for men who also take nitrates, commonly used to treat angina, because the drug combination can cause blood pressure to plummet, the FDA said in an announcement. In addition, the agency cautions that PDE5 inhibitors may, on rare occasions, trigger color vision changes, a sudden loss of vision or hearing, and erections lasting more than 4 hours.
Avanafil is to be taken on an as-needed basis 30 minutes before sexual activity. Clinicians should prescribe the lowest dose that works for an individual patient.
The FDA said that 3 clinical trials involving 1267 patients established the safety and effectiveness of the new drug. They were randomly assigned to take various doses of avanafil or a placebo for up to 12 weeks. Patients receiving avanafil reported significant gains in erectile function, vaginal penetration, and successful intercourse.
The most common adverse events, reported in more than 2% of patients in the clinical trial, were headache, flushing in the face and other areas, nasal congestion, symptoms of nasopharyngitis, and back pain.
Dosage and Administration
Avanafil is available as 50-mg, 100-mg, and 200-mg tablets. The starting dose of avanafil for most men is 100 mg taken as needed, not more than once a day, approximately 30 minutes before sexual activity. Based on efficacy and/or tolerability, the dose may be increased to 200 mg or decreased to 50 mg. Patients should use the lowest dose that is effective.
Avanafil may be taken with or without food. It must not be used with strong cytochrome P450 3A4 (CYP3A4) inhibitors, and the dose should not exceed 50 mg in a 24-hour period for patients taking a moderate CYP3A4 inhibitor. The recommended starting dose is 50 mg in patients receiving stable alpha-blocker therapy.
Contraindications, Warnings, and Precautions
Avanafil is contraindicated in patients using any form of organic nitrate or in those with hypersensitivity to any component of the avanafil tablet.
Patients in whom sexual activity is inadvisable because of cardiovascular status or any other reason should not use avanafil.
Hypotension may result in patients taking avanafil with alpha-blockers, other antihypertensive drugs, or more than 3 units of alcohol.
If an erection lasts longer than 4 hours, patients should seek emergency treatment.
A sudden loss of vision in 1 or both eyes could be a sign of nonarteritic ischemic optic neuropathy (NAION). Patients with these symptoms should discontinue avanafil and seek medical care, as should those who have a sudden decrease or loss of hearing. Patients with a history of NAION should be advised of the increased risk for NAION with avanafil.
Avanafil must not be used in patients with severe renal impairment or hepatic impairment, because the pharmacokinetics have not been studied in such patients.
Laurie Barclay, MD, has contributed to this synopsis.
- For most men, the starting dose of avanafil is 100 mg taken as needed for ED, not more than once a day, approximately 30 minutes before sexual activity. The dose may be increased to 200 mg or decreased to 50 mg based on efficacy and/or tolerability. Patients should use the lowest dose that is effective. Avanafil may be taken with or without food.
- Avanafil is contraindicated in patients using any form of organic nitrate because of the risk for hypotension. Hypotension may also occur in patients taking avanafil with alpha-blockers, other antihypertensive drugs, or more than 3 units of alcohol. Patients should seek emergency treatment if an erection lasts longer than 4 hours or if they experience a sudden loss of vision in 1 or both eyes.
- Common adverse events associated with avanafil may include headache, flushing in the face and other areas, nasal congestion, symptoms of nasopharyngitis, and back pain.
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