Tissue dispostion and excretion of gold and ¹⁴C in rats treated with sodium aurothio[1,4-¹⁴C]malate or thio [1,4-¹⁴C] malic acid

Abstract

1. In rats injected intramuscularly with sodium aurothio[1,4-¹⁴C]malate, 80% of the ¹⁴C was excreted in the urine, mostly in 24 h, 2% in the faeces and 10% as ¹⁴CO₂ in the expired air during the first six hours with none thereafter. Urinary and faecal gold represented 5% and 2.5% of the dose, respectively.

2. In rats given thio[1,4-¹⁴C]malic acid, 50% of the ¹⁴C was excreted in the urine, 10% in the expired air as ¹⁴CO₂ and 2% in the faeces.

3. Radioactivity was found in all tissues with distribution similar for the two compounds, the major sites of accumulation being bone, kidney and liver. Significantly higher amounts of ¹⁴C were found in the ¹⁴C-aurothiomalate-dosed animals, notably in bone and kidney.

4. Gold was located principally in kidney, liver, lung and spleen with smaller amounts elsewhere.

5. At least seven radioactive metabolites (including sodium aurothiomalate and thio-malic acid) were present in the urine of rats given ¹⁴C-aurothiomalate.

6. Urine from ¹⁴C-thiomalic acid-treated rats contained at least five radiolabelled compounds, one of which was thiomalic acid.

7. Results show that most of the gold was removed from the thiomalate moiety, however, the ¹⁴C distribution and the radioactive metabolites in urine demonstrated that some intact aurothiomalate remains.