Tadalafil
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Tadalafil
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| Systematic (IUPAC) name | |
| (6R-trans)-6-(1,3-benzodioxol-5-yl)- 2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino [1', 2':1,6] pyrido[3,4-b]indole-1,4-dione | |
| Identifiers | |
| CAS number | 171596-29-5 |
| ATC code | G04BE08 |
| PubChem | 110635 |
| DrugBank | APRD00071 |
| Chemical data | |
| Formula | C22H19N3O4 |
| Mol. weight | 389.404 g/mol |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Protein binding | 94% |
| Metabolism | ? |
| Half life | 17.5 hours |
| Excretion | ? |
| Therapeutic considerations | |
| Pregnancy cat. |
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| Legal status | |
| Routes | ? |
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.
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[edit] Tadalafil at work
It works by inhibiting an enzyme known as PDE5. A 20 mg dose of Tadalafil is comparable to a 100 mg dose of sildenafil (Viagra).
[edit] Chemical information
The empirical formula for tadalafil is C22H19N3O4, and its official organic name is (6R,12aR)-6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a- hexahydro-2-methyl-pyrazino[1 ,2 :1,6]pyrido[3,4-b]indole-1,4-dione. The molecular weight is 389.41. The tablets are yellow, film-coated, and almond-shaped, and are produced in 5, 10, or 20mg doses.
[edit] Side effects
The most common side effects when using tadalafil are headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. These side effects usually go away after a few hours. Patients who get back pain and muscle aches usually get it 12 to 24 hours after taking the drug, and the symptom usually goes away after 48 hours.
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.
[edit] Drug interactions — organic nitrates
Since PDE5 inhibitors such as tadalafil may cause transiently low blood pressure (hypotension), organic nitrates should not be taken for at least 48 hours after taking the last dose of tadalafil. Using organic nitrates (such as the sex drug Amyl nitrite) within this timeframe may increase the risk of life-threatening hypotension.
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 [1]. In the event of a medical emergency, paramedics and medical personnel should be notified of any recent doses of tadalafil.
[edit] Marketing
In the United States, Eli Lilly has a multiyear agreement to promote tadalafil (Cialis) with professional golf's PGA TOUR.
[edit] Trivia
- Some individuals with the surname of "Cialis" objected to the naming of Lilly's drug, but the pharmaceutical giant insists that the drug's name has nothing to do with the surname. [2]
[edit] Cialis drug history
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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).
[edit] External links
| Urologicals (G04) edit | ||
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| Acidifiers: | ||
| Urinary antispasmodics: |
Darifenacin, Emepronium, Flavoxate, Meladrazine, Oxybutynin, Propiverine, Solifenacin, Terodiline, Tolterodine, Trospium |
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| For erectile dysfunction: |
Alprostadil, Apomorphine, Moxisylyte, Papaverine, Phentolamine, Sildenafil, Tadalafil, Vardenafil, Yohimbine |
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| Other urologicals: |
Acetohydroxamic acid, Collagen, Dimethyl sulfoxide, Magnesium hydroxide, Phenazopyridine, Phenyl salicylate, Succinimide |
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| For benign prostatic hypertrophy: |
5α-reductase inhibitors: Dutasteride, Finasteride |
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| Selective Phosphodiesterase inhibitors (C01CE, G04BE)edit | ||
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| PDE1: | ||
| PDE2: | ||
| PDE3: | ||
| PDE4: | ||
| PDE5: |
Sildenafil, Tadalafil, Vardenafil |
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