The advent of sildenafil citrate (Viagra®) in 1998 from Pfizer (New York) revolutionized ED treatment and discussion, bringing this stigmatized problem out into the open. Most patients prefer oral medical therapy, partly because the convenience of oral medication decreases the embarrassment of discussing ED (Hatzichristou et al., 2000), and many men in the United States asked their provider to try the medication. Even some well-known public figures, including a politician, spoke up about having ED. The drug was initially studied for the treatment of angina because of the vascular dilating effects, but it also improved ED among participants during clinical trials (Katzenstein, Grossman, & Ignarro, 2001).
The mechanism of action is to amplify the nitric oxide (NO)-cyclic guanosine monophoshate (cGMP) pathway of vasodilatation through competitive inhibition of the cGMP breakdown mechanism (Porst et al., 2013). Phosphodiesterase type-5 (PDE-5) breaks down cGMP, and this drug is a PDE-5 inhibitor (PDE-5i). Other oral agent PDE-5i agents followed in 2003, including tadalafil (Cialis®) and vardenafil hydrochloride (Levitra®).
Since their release, these medications continued to rise in cost, and many men complained about paying up to $86 per pill for some medications. Most recently, generic versions of these medications have become available, making the drugs more affordable and accessible. A different version of the PDE-5i medication goes through the oral mucosa rather than the stomach. Vardenafil HCL (Staxyn®) is a 10 mg disintegrating tablet that dissolves on the tongue within the mouth approved by the FDA in 2010. The most recent drug to be approved was avanafil (Stendra®) in 2012. It is a 50 to 200 mg tablet that is swallowed by mouth to go through the stomach for absorption. The peak effect occurs more rapidly in about half the time of the traditional PDE-5i and is mostly gone from the body in 3 hours.
Urol Nurs. 2019;39(5):262-264. © 2019 Society of Urologic Nurses and Associates