sulfoaildenafil sulfoaildenafil sulfoaildenafil (thioaildenafil) is a synthetic drug that is a structural analog of sildenafil (viagra). it was first reported in 2005, and it is not approved by any health regulation agency. like sildenafil, sulfoaildenafil is a phosphodiesterase type 5 inhibitor. sulfoaildenafilclinical dataother namesthiomethisosildenafil; sildenafil thione; thioaildenafillegal statuslegal status unapproved and unscheduled identifiers iupac name 5-sulfonyl-2-ethoxyphenyl]-1-methyl-3-propyl-4h-pyrazolopyrimidine-7-thione cas number856190-47-1pubchem cid56841591chemspider24751855unii33dx49e09gcomptox dashboard (epa)dtxsid20234860 chemical and physical dataformulac23h32n6o3s2molar mass504.67 g·mol−13d model (jsmol)interactive image smiles cccc1=nn(c2=c1nc(=nc2=s)c3=c(c=cc(=c3)s(=o)(=o)n4c(n(c4)c)c)occ)c inchi inchi=1s/c23h32n6o3s2/c1-6-8-18-20-21(28(5)27-18)23(33)26-22(25-20)17-11-16(9-10-19(17)32-7-2)34(30,31)29-12-14(3)24-15(4)13-29/h9-11,14-15,24h,6-8,12-13h2,1-5h3,(h,25,26,33)/t14-,15+key:sclukepfxxparw-gascztmlsa-n sulfoaildenafil has been found as an adulterant in a variety of supplements which are sold as "natural" or "herbal" sexual enhancement products. a range of designer analogues of usa fda-approved inhibitors of type-5 cgmp-specific phosphodiesterase (pde5), such as sildenafil and vardenafil, have been detected in recent years as adulterants in over-the-counter herbal aphrodisiac products and dietary supplements, in an apparent attempt to circumvent both the legal restrictions on sale of erectile dysfunction drugs, which are prescription-only medicines in most western countries, and the patent protection which prevents sale of these drugs by competitors except under license to their inventors. these compounds have been demonstrated to display pde5 inhibitory activity in vitro and presumably have similar effects when consumed, but have undergone no formal testing in either humans or animals, and as such represent a significant health risk to consumers of these products due to their unknown safety profile. some attempts have been made to ban these drugs as unlicensed medicines, but progress has been slow so far, as even in those jurisdictions which have laws targeting designer drugs, the laws are drafted to ban analogues of illegal drugs of abuse, rather than analogues of prescription medicines. however at least one court case has resulted in a product being taken off the market. in december 2010, the united states food and drug administration (fda) issued a warning to consumers about such products stating, "the fda has found many products marketed as dietary supplements for sexual enhancement during the past several years that can be harmful because they contain active ingredients in fda-approved drugs or variations of these ingredients."