STENDRA (avanafil) is a selective inhibitor of cGMP-specific PDE5.

Avanafil is designated chemically as (S)-4-[(3-Chloro-4-methoxybenzyl)amino]-2-[2-(hydroxymethyl)-1-pyrrolidinyl]-N-(2-pyrimidinylmethyl)-5-pyrimidinecarboxamide and has the following structural formula:

Avanafil occurs as white crystalline powder, molecular formula C₂₃H₂₆ClN₇O₃ and molecular weight of 483.95 and is slightly soluble in ethanol, practically insoluble in water, and soluble in 0.1 mol/L hydrochloric acid. STENDRA, for oral administration, is supplied as oval, pale yellow tablets containing 50 mg, 100 mg, or 200 mg avanafil debossed with dosage strengths. In addition to the active ingredient, avanafil, each tablet contains the following inactive ingredients: mannitol, fumaric acid, hydroxypropylcellulose, low substituted hydroxypropylcellulose, calcium carbonate, magnesium stearate, and ferric oxide yellow.

Avanafil relaxes muscles and increases blood flow to particular areas of the body.

Avanafil is used to treat erectile dysfunction (impotence).

Avanafil may also be used for purposes not listed in this medication guide

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

If you become dizzy or nauseated during sexual activity, or if you have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of avanafil.

Stop using avanafil and call your doctor at once if you have any of these serious side effects:

• changes in vision or sudden vision loss;
• ringing in your ears, or sudden hearing loss;
• chest pain, pounding heartbeats or fluttering in your chest;
• pain, swelling, warmth, or redness in one or both legs;
• shortness of breath, swelling in your hands or feet;
• feeling light-headed, fainting; or
• penis erection that is painful or lasts 4 hours or longer.

Do not take avanafil if you are allergic to it, or if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin (Nitro Dur, Nitrolingual, Nitrostat, Transderm Nitro, and others), isosorbide dinitrate (Dilatrate, Isordil, Isochron), isosorbide mononitrate (Imdur, ISMO, Monoket), or recreational drugs such as amyl nitrate or nitrite ("poppers"). Taking avanafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

If you become dizzy or nauseated during sexual activity, or if you have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of avanafil.

Do not take avanafil more than once a day. Allow 24 hours to pass between doses.

Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.

Avanafil can decrease blood flow to the optic nerve of the eye, causing sudden vision loss. This has occurred in a small number of people taking a similar medication called sildenafil (Viagra). Most of these people also had heart disease, diabetes, high blood pressure, high cholesterol, or certain pre-existing eye problems, and in those who smoke or are over 50 years old.

Stop using avanafil and get emergency medical help if you have sudden vision loss.

Less serious side effects may include:

• redness or warmth in your face, neck, or chest;
• headache, mild dizziness;
• cold symptoms such as stuffy nose, sinus pain, or sore throat;
• diarrhea, constipation, upset stomach; or
• back pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.