Comparison of 2-mercaptopropionylglycine and D-penicillamine in the treatment of cystinuria.

We have compared 2-mercaptopropionylglycine (MPG) with D-penicillamine in its capacity to reduce the urinary excretion of cystine by patients with cystinuria. Satisfactory ion-exchange chromatographic methods for the measurement of urinary MPG, D-penicillamine, cystine and the cysteine-disulfides of the two drugs have been developed, and we have established the time course of the excretion of these substances after oral intake of each drug. MPG was found to be approximately one and a half times as effective as D-penicillamine, both in reducing urinary excretion of free cystine and in the amounts of mixed disulfide which appeared in the urine.