Metabolism of Ethylenediaminedihydriodide and Sodium or Potassium Iodide by Dairy Cows

Abstract

Simultaneous single doses of 125I-labeled ethylenediaminedihydriodide and sodium iodide-131 were given orally to two cows and intravenously to two cows. Radioiodine from the two sources was nearly identical in blood, milk, urine, and feces throughout a 6-day collection. Three dry cows (one pregnant) were given daily oral doses of 125I-labeled ethylenediaminedihydriodide and sodium iodide-131. After 6 days, percentages of daily doses of iodine-125 from ethylenediaminedihydriodide compared to iodine-131 from sodium iodide averaged 10% higher in plasma, 20% lower in feces, and 4% lower in urine. Recovery of iodine-125 from soft tissues and organs, including an 8-month fetus, averaged 11% higher than iodine-131 and iodine-125 was 13% higher in cartilage. Radioiodine retention, calculated as that not accounted for by excretion or recovery from digestive tract contents at slaughter, averaged 16% more from ethylenediaminedihydriodide than from sodium iodide. These differences were not observed for a cow simultaneously dosed with iodine-125 and iodine-131, both as sodium iodide. Feeding 100 milligrams ethylenediaminedihydriodide daily to lactating cows for 7 to 8 weeks, in comparison to potassium iodide, caused increased concentration of iodine in milk, less in urine, and about equal in feces. Ethylenediaminedihydriodide is absorbed equal to or better than sodium or potassium iodide and iodine from it is retained in most organs and tissues longer than iodine from sodum iodide.