aildenafil aildenafil aildenafil (methisosildenafil) is a synthetic drug that is a structural analog of sildenafil (viagra). it was first reported in 2003, and it is not approved by any health regulation agency. like sildenafil, aildenafil is a phosphodiesterase type 5 inhibitor. aildenafilclinical dataother namesmethisosildenafil; dimethyl sildenafillegal statuslegal status unapproved and unscheduled identifiers iupac name 5-sulfonyl-2-ethoxyphenyl]-1-methyl-3-propyl-6h-pyrazolopyrimidin-7-one cas number496835-35-9pubchem cid135452876chemspider8316620unii9t49w8gax6comptox dashboard (epa)dtxsid10197970 chemical and physical dataformulac23h32n6o4smolar mass488.61 g·mol−13d model (jsmol)interactive image smiles cccc1=nn(c2=c1n=c(nc2=o)c3=c(c=cc(=c3)s(=o)(=o)n4c(n(c4)c)c)occ)c inchi inchi=1s/c23h32n6o4s/c1-6-8-18-20-21(28(5)27-18)23(30)26-22(25-20)17-11-16(9-10-19(17)33-7-2)34(31,32)29-12-14(3)24-15(4)13-29/h9-11,14-15,24h,6-8,12-13h2,1-5h3,(h,25,26,30)/t14-,15+key:nfswszipxjaylr-gascztmlsa-n aildenafil has been found as an adulterant in a variety of supplements which are sold as "natural" or "herbal" sexual enhancement products. the united states food and drug administration has warned consumers that any sexual enhancement product that claims to work as well as prescription products is likely to contain such a contaminant.