Thursday, June 18, 2009

PDE-5 Inhibitors-FDA Approved Medication

Currently, there are three oral medications approved by the Food and Drug Administration (FDA) for the treatment of erectile dysfunction: Sildenafil (Viagra), Vardenafil (Levitra), and Tadalafil (Cialis). All these agents block the enzyme phosphodiesterase type 5 (PDE-5) and belong to a class of drugs called phosphodiesterase (PDE) inhibitors.

Since introduction of the first PDE-5 inhibitor Viagra, there has been a fundamental change in the treatment of erectile dysfunction. Although there are a number of options available for non-surgical treatment, it is clear that oral therapy has revolutionized the treatment approach to patients with erectile dysfunction. The development of the PDE-5 inhibitors Levitra and Cialis prompts the question of whether and how these three medications differ in terms of their efficacy and adverse effects.

Viagra was the first and is probably the most famous of the three PDE-5 inhibitors used to treat erectile dysfunction. Viagra was approved as an effective agent for treating erectile dysfunction in March 27, 1998. Viagra is manufactured by Pfizer, Inc.

Levitra was the second PDE-5 inhibitor to come to market in the United States, and it was approved by the FDA in August 19, 2003. Levitra is manufactured by Bayer Pharmaceuticals Corporation.

Cialis was the third PDE-5 inhibitor to come to market in the United States and was approved by the FDA at the end of November 21, 2003. Cialis is manufactured by Lilly ICOS LLC.

The major advantage of PDE-5 inhibitors is that they do not cause an erection at inappropriate times, because they act only in response to sexual stimulation. If there is no sexual stimulation drug remains in the background. All three are taken orally prior to planned sexual activity, acting to increase blood flow in the penis in response to sexual stimulation. However, there are important differences between the three, differences that could influence safety, specificity, duration of action, adverse effects, and ultimately, public acceptance within this class of drug. View this article.

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