Tiopronin is a prescription thiol drug used to control the rate of cystine precipitation and excretion in the disease cystinuria. Target: Others Tiopronin is used primarily for cystinuria and is well known in the cystinuric community. Depending on the severity of a person's cystinuria, tiopronin may be taken for life, possibly starting in early childhood. It may also be used for Wilson's disease (an overload of copper in the body), and certain types of rare arthritis, though tiopronin is not an anti-inflammatory. Tiopronin is also sometimes used as a stabilizing agent for metal nanoparticles. The thiol group binds to the nanoparticles, preventing coagulation [1, 2].