NCIt definition : An acylated sulfhydryl-containing derivative of glycine with reducing and complexing
properties. Tiopronin breaks the disulphide bond of cystine and binds the sulfhydryl
group of the resultant cysteine monomers to form a soluble tiopronin-cysteine-mixed
disulfide, which is more water-soluble than cystine and is readily excreted. This
leads to a reduction in urinary cystine concentration and subsequently reduces cystine
stone formation.;