Sildenafil
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| sildenafil | |||||||
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| Uses: | Erectile Dysfunction | ||||||
| Properties: | PDE-5 inhibitor | ||||||
| Hazards: | cardiovascular risks | ||||||
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Sildenafil, widely known as Viagra®, is a medication used to treat erectile dysfunction. It is also marketed as Ravatio® as an oral treatment for pulmonary arterial hypertension. Both drugs are sold as the citrate salt of sildenafil. It was the first commercialized selective phosphodiesterase type 5 (PDE-5) inhibitor and was immediately popular both for treating erectile dysfunction and for recreational use. Sildenafil works by binding to phosphodiesterase type-5 enzymes, competing with the natural ligand cyclic guanine monophosphate (cGMP), which is structurally similar to sildenafil. Vardenafil, a newer and more potent PDE-5 inhibitor, is nearly identical to sildenafil, while tadalafil is considerably different in structure.
Chemistry
The IUPAC name of sildenafil is 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl)-4-ethoxyphenyl] sulfonyl]-4-methylpiperazine and it has a molecular mass of 666.7 g/mol (as the citrate salt).
Drug interactions
Because sildenafil has vasodilator properties that result in decreased blood pressure, the combined use of sildenafil with other vasodilators, such as alpha-blockers, must be done cautiously. Patients with a history of heart attacks, strokes, arrythmia, hypertension, retinitis pigmentosa or currently on bosentan therapy.
Up-to-Date Information
The most up-to-date information about this and other drugs can be found at the following sites.
- Sildenafil - FDA approved drug information (drug label) from DailyMed (U.S. National Library of Medicine).
References
J. D. Corbin and S. H. Sharron. "Molecular Biology and Pharmacology of PDE-5-Inhibitor Therapy for Erectile Dysfunction". J. Androl. 24: S38-S41.