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Description: Sildenafil (in citrate form), sold under the names Viagra, Revatio and under various other names, is a drug used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH), developed by the pharmaceutical company Pfizer. Its primary competitors on the market are tadalafil (Cialis), and vardenafil (Levitra). [Wikipedia]
Drug Type: Small Molecule; Approved; Investigational
Pharmacology: Sildenafil is used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in the corpus cavernosum, resulting in increased inflow of blood and an erection. Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. This means that, with Sildenafil on board, normal sexual stimulation leads to increased levels of cGMP in the corpus cavernosum which leads to better erections. Without sexual stimulation and no activation of the NO/cGMP system, Sildenafil should not cause an erection.
Mechanism of Action: Sildenafil inhibits the cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by Sildenafil enhances erectile function by increasing the amount of cGMP.
Indication: For the treatment of erectile dysfunction
Half Life: 4 hours
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Data Correlations | 3 studies

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Genes category icon Genes
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PDE5A 100 100
FBXW5 100 100
RBM8A 92 92
RGN 89 89
TOLLIP 86 86
PON1 84 84
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Neuroactive Ligand Receptor Interac… 100 100
IGF-1 mTOR Pathway 99 99
G-Protein Signaling Pathway 98 98
Rhodopsin Like 98 98
Calcium Regulation In Cardiac Cells 98 98
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  • David A Kass
  • Vojtech Melenovsky
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