Famotidine EP Impurity - B

3,5-Bis[2-[[[2-[(Diaminomethylene)amino]thiazol-4-yl]methyl]thio]-ethyl]-4H-1,2,4,6-thiatriazine-1,1-dioxide; N,N'''-[(1,1-Dioxido-2H-1,2,4,6-thiatriazine-3,5-diyl) bis(2,1-ethanediylthiomethylene-4,2-thiazolediyl)]bisguanidine; Famotidine dimer, Famotidine Related Compound B (USP);