Carbidopa, an inhibitor of aromatic amino acid decarboxylation, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 244.3. It is designated chemically as ()-L-?-hydrazino-?-methyl-?-(3,4-dihydroxybenzene) propanoic acid monohydrate. Its empirical formula is C10H14N2O4H2O, and its structural formula is: