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| Tadalafil is a drug used to treat male erectile
dysfunction (impotence). It was developed by the biotechnology firm
ICOS and marketed worldwide by Eli Lilly and Company under the brand
name Cialis.
In the United States, tadalafil has Food and Drug Administration approval and became available in December, 2003 as the third impotence pill after sildenafil (Viagra) and vardenafil (Levitra). Due to its 36-hour effect it is also known as the weekend pill. Tadalafil at work Chemical information Side effects In May 2005, the U.S. Food and Drug Administration found that tadalafil (along with other PDE5 inhibitors) could lead to vision impairment in certain patient groups, including diabetics. An investigation is currently ongoing. Drug interactions — organic nitrates Since people who have taken tadalafil within the past 48 hours cannot take organic nitrates to relieve angina (GTN Spray), these patients should seek immediate medical attention if they experience anginal chest pain . In the event of a medical emergency, paramedics and medical personnel should be notified of any recent doses of tadalafil. Marketing Trivia Cialis drug history The history of Cialis cannot be discussed without mentioning Pfizer's drug, Viagra. The FDA's approval on March 27, 1998, led this prescription drug, Viagra, to a ground breaking success in just the first year of introduction as Pfizer sold drugs worth over a billion dollars. However, things changed considerably for the giant of erectile dysfunction drugs when the FDA also approved Levitra in August 19, 2003, and Cialis in November 21, 2003. In 1993 the drug company Icos began studying IC351, which is a PDE5 enzyme inhibitor, and this is basically the process through which the erectile dysfunction drugs work. In 1994, Pfizer scientists discovered that Sildenafil Citrate, which is a white crystalline powder that temporarily normalizes erectile function of the penis by blocking an enzyme known to inhibit the production of a chemical that causes erections, caused the heart patients that were participating in a clinical study of a heart medicine to have erections. Although the scientists were not testing the chemical compound IC351 for erectile dysfunction, the compound seemed to have a side effect which could potentially be worth millions, if not billions of dollars. Soon Icos received its very first patent in 1994 on IC351, and the clinical trials of phase I took place in 1995. In 1997, phase II clinical studies began and Icos performed its first study on patients with erectile dysfunction. Phase II lasted about two years, and after that phase III began. In 1998, ICOS Corporation, and Eli Lilly and Company, commercialized
the drug for erectile dysfunction, and two years later they filed
a new drug application with the U.S. Food and Drug Administration
for IC351; the only difference was that this time they decided to
call the drug, Cialis. In May of 2002,
Icos and Eli Lilly and Company reported to the American Urological
Association that the phase III tests show that Cialis
works for up to 36 hours, and one year later Icos and Eli Lilly
and Company received the U.S. FDA's approval for Cialis.
One advantage that Cialis has over Viagra
is that tadalafil has an half-life of
17.5 hours (and thus Cialis is advertised
to work for up to 36 hours) as compared to 4 hours half-life for
sildenafil
(Viagra). |