Chemical Component Summary

FormulaC22 H30 N6 O4 S
Molecular Weight474.58
Isomeric SMILESCCCc1c2c(n(n1)C)C(=O)NC(=N2)c3cc(ccc3OCC)S(=O)(=O)N4CCN(CC4)C

Chemical Details

Formal Charge0
Atom Count63
Chiral Atom Count0
Bond Count66
Aromatic Bond Count17

Drug Info: DrugBank

DrugBank IDDB00203 
  • approved
  • investigational
DescriptionIn eliciting its mechanism of action, sildenafil ultimately prevents or minimizes the breakdown of cyclic guanosine monophosphate (cGMP) by inhibiting cGMP specific phosphodiesterase type 5 (PDE5) [F3850, F3853, F3856, F3859, F3883, F3886, L5611, L5614]. The result of doing so allows cGMP present in both the penis and pulmonary vasculature to elicit smooth muscle relaxation and vasodilation that subsequently facilitates relief in pulmonary arterial hypertension and the increased flow of blood into the spongy erectile tissue of the penis that consequently allows it to grow in size and become erect and rigid [F3850, F3853, F3856, F3859, F3883, F3886, L5611, L5614]. Interestingly enough, it is precisely via this mechanism why sildenafil was at first researched as a potential treatment for angina - or chest pain associated with inadequate blood flow to the heart - before being serendipitously indicated for treating erectile dysfunction in the late 1980s [A175732]. Nevertheless, it is because of this mechanism that sildenafil is also indicated for treating pulmonary arterial hypertension but is also additionally notorious for interacting with various anti-anginal or anti-hypertensive agents to develop potentially rapid, excessive, and/or fatal hypotensive crises [A175579, A175582, A175654]. Regardless, sildenafil, among a variety of other similar or related PDE5 inhibitors, has become a common and effective treatment for erectile dysfunction and since its formal approval for medical use in the public in 1998 [A175732], continues to see millions of prescriptions written for it internationally. Although the medication has historically been most popularly recognized as Pfizer's brand name Viagra, sildenafil is currently available generically and even as a non-prescription over the counter medication in some countries [L5656].
  • Sildenafilo
  • Sildenafil citrate
  • Sildenafil
  • 1-((3-(4,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo(4,3-d)pyrimidin-5-yl)-4-ethoxyphenyl)sulfonyl)-4-methylpiperazine
Brand Names
  • Ipg-sildenafil
  • Bio-sildenafil
  • Auro-sildenafil
  • Dom-sildenafil
  • Ag-sildenafil
IndicationSildenafil is a phosphodiesterase-5 (PDE5) inhibitor that is predominantly employed for two primary indications: (1) the treatment of erectile dysfunction [A175582, L5611, F3853, F3856, F3886]; and (2) treatment of pulmonary hypertension, where: a) the US FDA specifically indicates sildenafil for the treatment of pulmonary arterial hypertension (PAH) (WHO Group I) in adults to improve exercise ability and delay clinical worsening [F3850]. The delay in clinical worsening was demonstrated when sildenafil was added to background epoprostenol therapy [F3850]. Studies establishing effectiveness were short-term (12 to 16 weeks), and included predominately patients with New York Heart Association (NYHA) Functional Class II-III symptoms and idiopathic etiology (71%) or associated with connective tissue disease (CTD) (25%) [F3850]; b) the Canadian product monograph specifically indicates sildenafil for the treatment of primary pulmonary arterial hypertension (PPH) or pulmonary hypertension secondary to connective tissue disease (CTD) in adult patients with WHO functional class II or III who have not responded to conventional therapy [F3859]. In addition, improvement in exercise ability and delay in clinical worsening was demonstrated in adult patients who were already stabilized on background epoprostenol therapy [F3859]; and c) the EMA product information specifically indicates sildenafil for the treatment of adult patients with pulmonary arterial hypertension classified as WHO functional class II and III, to improve exercise capacity [F3883]. Efficacy has been shown in primary pulmonary hypertension and pulmonary hypertension associated with connective tissue disease [F3883]. The EMA label also indicates sildenafil for the treatment of pediatric patients aged 1 year to 17 years old with pulmonary arterial hypertension [F3883]. Efficacy in terms of improvement of exercise capacity or pulmonary hemodynamics has been shown in primary pulmonary hypertension and pulmonary hypertension associated with congenital heart disease [F3883].
  • Agents Causing Muscle Toxicity
  • Amides
  • Cardiovascular Agents
  • Cytochrome P-450 CYP2C19 Inhibitors
  • Cytochrome P-450 CYP2C19 Inhibitors (weak)
  • G01AE10
  • G04BE03
CAS number139755-83-2

Drug Targets

NameTarget SequencePharmacological ActionActions
cGMP-specific 3',5'-cyclic phosphodiesteraseMERAGPSFGQQRQQQQPQQQKQQQRDQDSVEAWLDDHWDFTFSYFVRKAT...unknowninhibitor
Retinal rod rhodopsin-sensitive cGMP 3',5'-cyclic phosphodiesterase subunit gammaMNLEPPKAEFRSATRVAGGPVTPRKGPPKFKQRQTRQFKSKPPKKGVQGF...unknowninhibitor
Retinal cone rhodopsin-sensitive cGMP 3',5'-cyclic phosphodiesterase subunit gammaMSDNTTLPAPASNQGPTTPRKGPPKFKQRQTRQFKSKPPKKGVKGFGDDI...unknowninhibitor
View More
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS. Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682

Related Resource References

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