ppads ppads ppads (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid) is a selective purinergic p2x antagonist. it is able to block contractions of rabbit vas deferens induced by atp or α,β,methylene-atp. it appears to be relatively selective for p2x receptors, having no appreciable activity at α1 adrenergic, muscarinic m2 and m3, histamine h1, and adenosine a1 receptors. ppads names iupac name 4-pyridin-2-yl}diazenyl]benzene-1,3-disulfonic acid other names ppads identifiers cas number 149017-66-3 y192575-19-2 (tetrasodium salt) y 3d model (jsmol) interactive image chebi chebi:34941 y chemspider 20136164 pubchem cid 60931636532796 (tetrasodium salt) unii l6k2lj9bjk y inchi inchi=1s/c14h14n3o12ps2/c1-7-13(19)9(5-18)10(6-29-30(20,21)22)14(15-7)17-16-11-3-2-8(31(23,24)25)4-12(11)32(26,27)28/h2-5,19h,6h2,1h3,(h2,20,21,22)(h,23,24,25)(h,26,27,28)/b17-16+ smiles oc2c(c=o)c(cop(o)(=o)o)c(/n=n/c1ccc(cc1s(o)(=o)=o)s(o)(=o)=o)nc2c properties chemical formula c14h14n3o12ps2 molar mass 511.37 g·mol−1 appearance orange solid solubility in water 100 mm (tetrasodium salt) except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). infobox references