3-(((2-((diaminomethylene)amino)thiazol-4-yl)methyl)thio)propanoic acid|3-[[[2-[(Aminoiminomethyl)amino]-4-thiazolyl]methyl]thio]propanoic Acid;|3-[[[2-[(Diaminomethylene)amino]thiazol-4-yl]methyl]thio]propanoic Acid;|Famotidine Acid Impurity|Famotidine Acid Impurity;|Famotidine EP Impurity F ; 3-[[[2-[(Diaminomethylene)amino]thiazol-4-yl]methyl]sulphanyl]propanoic acid.|Famotidine Related Compound F|USP Famotidine Related Compound F ;