Viagra (Sildenafil)

Three Dimensional modelled molecular structure of Sildenafil

O=S(C1=C([H])C([H])=C(OCC)C(C(N2[H])=NC(C(CCC)=NN3C)=C3C2=O)=C1[H])(N4CCN(C)CC4)=O

Sildenafil, trade name VIAGRA^TM, chemical name 5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)phenyl]-1- methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one, formula C₂₂H₃₀N₆O₄S, was discovered through a rational drug design programme by the pharmaceutical company Pfizer. It is a potent selective inhibitor of the enzyme phosphodiesterase (PDE-5), which destroys cyclic guanosine monophosphate (cGMP), itself a dilator of blood vessels in the body. Viagra thus allows cyclic GMP to persist and this property has led to its use for the oral treatment of male erectile dysfunction (N. K. Terrett, A. S. Bell, D. Brown, P. Ellis Bioorganic & Medicinal Chem. Lett., 1996, 6, pp.1819-1824). It is adminstered as the citrate.

The structures below were modelled using a program called Chem3D from CambridgeSoft, using molecular mechanics (MM2) and quantum mechanics (AM1, PM3) methods. In all cases, the 6-H tautomer was found to be lower in energy than the 4-H isomer by about 4-8 kcal/mol, with its conformation locked by an NH...O hydrogen bond . To view these models, you will need to install a browser plug-in such as Chime or Chem3D Net plugin.

Style of Model
Zoom in out	Display spacefill ball & stick stick wireframe Tautomer Hydrogen bond

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