Urinary excretion of metals during treatment with D-penicillamine and 2-mercaptopropionylglycine in normal and cystinuric dogs.

Urinary excretion of metals during treatment with 2-mercaptopropionylglycine (2-MPG) was studied in 11 normal and 20 cystinuric male dogs. The results were compared with those obtained during D-penicillamine treatment. Twenty-four-h urine and morning samples of urine were taken for determination of 13 metals before and during treatment. After single intravenous and oral D-penicillamine treatment of the normal dogs, significant increases were found in the 24-h urinary excretion of Ca, Cu and Zn. Oral intake of D-penicillamine increased the excretion of Co, Cr, Fe and Mg as well. No effect on renal metal excretion was observed after single intravenous and up to 2 months of daily oral treatment with 2-MPG. In 14 cystinuric dogs no effect was found after single intravenous and oral administrations of 2-MPG. However, after oral treatment of six cystinuric dogs with 2-MPG for 2-4 months, significantly increased excretions of Ca and Mg were found. Fourteen of the cystinuric dogs were also investigated after 2-6 years of continuous 2-MPG treatment, and after this period no significant elevation in the urinary excretion of metals was found. The present study shows that in contrast to D-penicillamine, 2-MPG does not increase the urinary excretion of metals to any appreciable extent. Observed increases in the excretion of Ca and Mg seemed to be a temporary effect only.