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Sildenafil

Athanor · official

C22H30N6O4S · 474.6 g/mol

IUPAC name: 5-[2-ethoxy-5-(4-methylpiperazin-1-yl)sulfonylphenyl]-1-methyl-3-propyl-6H-pyrazolo[4,5-d]pyrimidin-7-one

Also called Viagra, Revatio, PDE5 inhibitor

DrugsRings
Open in Athanor
The structure of Sildenafil
Drawn from its SMILES with RDKit
Harmful or irritantWarningHarmful if swallowed · Causes serious eye irritation · Harmful to aquatic life with long lasting effects

Names and identifiers

IUPAC name
5-[2-ethoxy-5-(4-methylpiperazin-1-yl)sulfonylphenyl]-1-methyl-3-propyl-6H-pyrazolo[4,5-d]pyrimidin-7-one
Synonyms
Viagra, Revatio, PDE5 inhibitor
+ 38 more

Aphrodil, Vizarsin, Sildenafilo, Patrex, Sildenafil teva, Sildenafil actavis, Sildenafil ratiopharm, 3M7OB98Y7H, 1-((3-(4,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo(4,3-d)pyrimidin-5-yl)-4-ethoxyphenyl)sulfonyl)-4-methylpiperazine, HIP0908, HIP-0908, CHEBI:9139, DTXSID6023579, 1-[[3-(4,7-Dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine, Piperazine, 1-((3-(4,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo(4,3-d)pyrimidin-5-yl)-4-ethoxyphenyl)sulfonyl)-4-methyl-, sildenafilum, Nipatra, 5-(2-ethoxy-5-(4-methylpiperazine-1-sulfonyl)phenyl)-1-methyl-3-propyl-1H,4H,7H-pyrazolo(4,3-d)pyrimidin-7-one, 5-[2-ethoxy-5-(4-methylpiperazine-1-sulfonyl)phenyl]-1-methyl-3-propyl-1H,4H,7H-pyrazolo[4,3-d]pyrimidin-7-one, RefChem:6218, DTXCID003579, G04BE03, C22H30N6O4S, Sildenafil (INN), 5-(2-Ethoxy-5-((4-methylpiperazin-1-yl)sulfonyl)phenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one, CHEMBL192, 5-[2-ethoxy-5-(4-methyl-1-piperazinylsulfonyl)phenyl]-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one, 7H-Pyrazolo[4,3-d]pyrimidin-7-one, 5-[2-ethoxy-5-[(4-methyl-1-piperazinyl)sulfonyl]phenyl]-1,6-dihydro-1-methyl-3-propyl-, UK 92480-10, SILDENAFIL [INN], Sildenafil [INN:BAN], 5-{2-ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]phenyl}-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one, 5-{2-ETHOXY-5-[(4-METHYLPIPERAZIN-1-YL)SULFONYL]PHENYL}-1-METHYL-3-PROPYL-1H,6H,7H-PYRAZOLO[4,3-D]PYRIMIDIN-7-ONE, Aphrodil (TN), 5-[2-ethoxy-5-(4-methylpiperazin-1-yl)sulfonylphenyl]-1-methyl-3-propyl-6H-pyrazolo[4,3-d]pyrimidin-7-one, 5-{2-ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]phenyl}-1-methyl-3-propyl-1H,4H,7H-pyrazolo[4,3-d]pyrimidin-7-one, SMR000752512, HSDB 7305

Molecular formula
C22H30N6O4S
Empirical formula
C22H30N6O4S
Molecular weight
474.6 g/mol
Exact mass
474.20492
CAS number
139755-83-2
PubChem CID
135398744
Canonical SMILES
CCCC1=NN(C2=C1N=C(NC2=O)C3=C(C=CC(=C3)S(=O)(=O)N4CCN(CC4)C)OCC)C
Isomeric SMILES
CCCC1=NN(C2=C1N=C(NC2=O)C3=C(C=CC(=C3)S(=O)(=O)N4CCN(CC4)C)OCC)C
InChI
InChI=1S/C22H30N6O4S/c1-5-7-17-19-20(27(4)25-17)22(29)24-21(23-19)16-14-15(8-9-18(16)32-6-2)33(30,31)28-12-10-26(3)11-13-28/h8-9,14H,5-7,10-13H2,1-4H3,(H,23,24,29)
InChIKey
BNRNXUUZRGQAQC-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

Solubility in water
White to off-white crystalline powder; solubility in water: 3.5 mg/mL (sildenafil citrate)[1]
log P
log Kow = 2.75[1]

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
33
Rings
4
Aromatic rings
3
Fraction sp³ carbons (Fsp3)
0.5
H-bond donors
1
H-bond acceptors
7 computed here · PubChem 8
Rotatable bonds
7
TPSA (Ų)
113.4 computed here · PubChem 118
Formal charge
0
XLogP3
1.5 PubChem
Complexity
838 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C55.68%
  • H6.37%
  • N17.71%
  • O13.48%
  • S6.76%

Isotope pattern

100%474.20527%475.2088.9%476.2051.7%477.206478.207

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
1.61 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-3.67 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
2.74 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 474.59
  • log P ≤ 5 (Crippen): 1.61
  • H-bond donors ≤ 5: 1
  • H-bond acceptors ≤ 10: 7

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Warning

Most widely reported: 103 company reports to ECHA. Source [2].

  • Harmful or irritant
  • H302Harmful if swallowed (34% of reports)
  • H319Causes serious eye irritation (68.9% of reports)
  • H412Harmful to aquatic life with long lasting effects (33% of reports)

Precautionary statements: P264, P264+P265, P270, P273, P280, P301+P317, P305+P351+P338, P330, P337+P317, P501

View all classifications (2)
  • [2] European Chemicals Agency (ECHA) · 103 reports · WarningH302, H319, H412
  • [1] Hazardous Substances Data Bank (HSDB) · WarningH315, H319, H335

Storage

  • Sildenafil powder for oral suspension should be stored below 30 °C in its original package to protect the drug from moisture. Reconstituted sildenafil oral suspension should be stored below 30 °C or in a refrigerator at 2-8 °C; the suspension should not be frozen.[1]
  • Commercially available sildenafil citrate injection should be stored at 20-25 °C, but may be exposed to temperatures ranging from 15-30 °C.[1]
  • Commercially available sildenafil citrate tablets should be stored at 25 °C, but may be exposed to 15-30 °C.[1]
  • Keep container tightly closed in a dry and well-ventilated place. (sildenafil citrate)[1]

Safety data sheets on the supplier’s page: Vitas-M Laboratory, MuseChem, Combi-Blocks.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  2. [2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  3. [3]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  5. [5]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  6. [6]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  7. [7]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  8. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  9. ·Literature on PubChem

Data last updated 2026-10-14.