R-(+)-Warfarin Description Optically active R enantiomer of Warfarin. S-warfarin is found to be more potent than the R-isomer in producing an anticoagulant response. Specifications Cas No. 5543-58-8 Product ID W0273 Product Name R-(+)-Warfarin Synonym (+)-Warfarin Formula C19H16O4 Formula Wt. 308.33 Purity ≥98% References Hirsh J, Fuster V, Ansell J, et al. J Am Coll Cardiol. 7;41(9):1633-52 (2003).