avanafil, Stendra

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

What is the dosage for avanafil (Stendra)?

For most individuals, the recommended starting dose of avanafil is 100 mg per day taken about 30 minutes before sexual activity. Depending on the adequacy of the response or side effects, the dose may be increased to 200 mg or decreased to 50 mg a day. Individuals who are taking medications that moderately increase the blood levels of avanafil should not exceed a total dose of 50 mg in 24 hours (See drug interactions).

Which drugs or supplements interact with avanafil (Stendra)?

The breakdown and elimination of avanafil from the body may be decreased by several drugs, leading to increased blood levels of avanafil and possible toxicity. Ketoconazole (Nizoral), itraconazole (Sporanox), indinavir (Crixivan) and ritonavir (Norvir), atazanavir (Reyataz), clarithromycin (Biaxin), nelfinavir (Viracept), saquinavir (Invirase), telithromycin (Ketek) profoundly increase blood levels of avanafil and should not be combined with avanafil.

The dose of avanafil should not exceed 50 mg daily when combined with erythromycin, amprenavir (Agenerase), aprepitant (Emend), diltiazem (Cardizem), fluconazole (Diflucan), fosamprenavir (Lexiva), and verapamil (Calan) because these drug moderately increase blood levels of avanafil.

Avanafil exaggerates the increases in heart rate and lowering of blood pressure caused by nitrates, for example, nitroglycerin, isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, Ismo, Monoket), and nitroglycerin (Nitro-Dur, Transderm-Nitro) that are used primarily for treating heart pain (angina). In patients who take nitrates for angina, avanafil could cause heart pain or possibly even a heart attack by exaggerating the increase in heart rate and the lowering of blood pressure. Therefore, avanafil should not be used with nitrates. If nitrates must be administered to a patient who has taken avanafil, at least 12 hours should elapse after the last dose of avanafil before administering the nitrates. Avanafil also exaggerates the blood pressure lowering effects of some alpha-blocking drugs for example, terazosin (Hytrin) that primarily are used for treating high blood pressure or enlargement of the prostate. Individuals who take these alpha-blockers should be on a stable dose of the alpha-blocker before avanafil is started. In such situations, avanafil should be started at the 50 mg dose. If the patient is already taking avanafil, the alpha-blocker should be started at the lowest dose.

Avanafil and alcohol both lower blood pressure. Therefore, combining avanafil with alcohol may cause excessive drops in blood pressure and cause dizziness, headaches, and increased heart rate.

Avanafil should not be combined with other PDE5 inhibitors used for treating impotence, for example, vardenafil (Levitra) or sildenafil (Viagra, Revatio).

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