Avanafil

Avanafil belongs to the class of PDE5 inhibitors, the same family as sildenafil, tadalafil, and vardenafil, which are the standard oral treatments for erectile dysfunction. ^[1] It is a second-generation member of the class, developed with the aim of acting quickly and selectively while causing fewer off-target effects.

Its main distinguishing features are speed and selectivity. Avanafil reaches peak blood levels in about thirty to forty-five minutes, and in trials many men were able to have intercourse within roughly fifteen minutes of taking it. ^[2] Its high selectivity for PDE5 over related enzymes, such as PDE6 in the retina, is thought to reduce the visual side effects seen with some older drugs. ^[3]

Avanafil was invented at Mitsubishi Tanabe Pharma in Japan and licensed to Vivus, which brought it to market. ^[1] It was approved by the US Food and Drug Administration in 2012 and by European regulators in 2013, and it is sold as Stendra in the United States and Spedra in Europe. It is a prescription-only medicine.

Randomized, placebo-controlled trials have found avanafil effective across a broad range of men with erectile dysfunction, improving standardized scores of erectile function and rates of successful intercourse. ^[1][4] Systematic reviews and meta-analyses pooling these trials confirm that it is both effective and generally well tolerated, with the higher dose giving somewhat greater benefit at the cost of more headaches. ^[2][3]

The most common side effects are headache, flushing, nasal congestion, and back pain, most of which are mild and short-lived. ^[2] Like other PDE5 inhibitors, avanafil must not be combined with nitrate heart medicines, because that combination can cause a dangerous drop in blood pressure. It is taken by mouth as needed before sexual activity.

Avanafil is prescription only. Common side effects are headache, facial flushing, stuffy nose, back pain, and dizziness. It is strictly off limits with nitrate heart medicines and with the pulmonary drug riociguat, because the combination can cause a life threatening drop in blood pressure. It should be used carefully with alpha blockers and with strong CYP3A4 inhibitors like ketoconazole or ritonavir, which raise its levels. Rare but serious risks include a painful erection lasting over four hours (priapism), sudden vision loss in one eye, and sudden hearing loss; any of these warrant urgent care.

Avanafil shares the same pharmacodynamic interaction with nitrates as other phosphodiesterase-5 inhibitors; co-administration with nitrates causes severe vasodilation and hypotension and is contraindicated ^[5]. In a direct clinical comparison with sildenafil, avanafil was given at 200 mg followed by glyceryl trinitrate 0.4 mg sublingually at various time intervals. Symptomatic hypotension occurred in 27% of subjects receiving avanafil and clinically significant standing systolic blood pressure reduction (at least 30 mmHg) in 15% ^[5]. However, no significant hemodynamic interaction was observed when the interval between avanafil and nitrate dosing was at least 8 hours or longer, suggesting the interaction is time-dependent.

Avanafil is also metabolized by CYP3A4; CYP3A4 inhibitors would be expected to increase avanafil levels, though formal pharmacokinetic studies of this interaction are not documented in the literature. Like other PDE5 inhibitors, use with alpha-blockers requires monitoring.

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Avanafil was discovered at Mitsubishi Tanabe Pharma in Japan as a second-generation phosphodiesterase type 5 inhibitor, designed for rapid onset and high selectivity relative to the earlier drugs in its class. Development and commercialization rights were licensed to the U.S. company Vivus, which brought it through late-stage trials for erectile dysfunction. The Food and Drug Administration approved it in April 2012 under the brand name Stendra, and European approval followed in 2013 under the name Spedra. It thus entered the market more than a decade after sildenafil, positioned on the strength of its faster absorption and refined receptor selectivity.

Avanafil has earned a favorable reputation as the fast-acting member of the PDE5 inhibitor family, often absorbed and effective within roughly thirty to forty-five minutes, which appeals to users who prefer less advance planning. Randomized trials and a 2023 meta-analysis support its efficacy and a generally reassuring safety profile, with its high selectivity for PDE5 credited for a lower incidence of visual side effects tied to PDE6. It is frequently described as well tolerated, with headache and flushing among the more common complaints. As a newer entrant it is valued for combining proven class efficacy with a quicker, more convenient onset.