2,4,6,8-Tetraoxa-5-phosphanonanedioic acid, 5-[[2-(6-amino-9H-purin-9-yl)-1-methylethoxy]methyl]-, bis(2,2-dimethylpropyl) ester, 5-oxide, (R)- 202138-50-9 AIDS-031697 AIDS031697 Bis(NeopentylOC)PMPA PMPA prodrug Tenofovir prodrug