AbstractComparative studies of oral and intravenous administration of tritiated dextran sulfate in rats showed markedly different distribution patterns. Following IV dosing about 50 per cent of the radioactivity was recovered in feces and urine within 24 h. The major portion of the recoverable dose was eliminated in the urine as dextran sulfate within 3 h after administration. In orally treated rats only about 32 per cent of the 3H was recovered in the feces and urine, the major fraction being associated with unabsorbed dextran sulfate in the feces. The remainder of the dose in both treatment groups has apparently distributed throughout the rat body with some accumulation in the liver, kidney and spleen. Consequently, the disposition of about 67 per cent or the oral dose could not be fully accounted for by these excretion routes. However, separation with Sephadex columns showed similarities in the 24 h plasma and urine profiles of the IV and orally dosed rats which suggest that while the oral dose was absorbed as dextran sulfate, it underwent rapid metabolism to small molecular weight products prior to entering the systemic circulation which were then widely distributed within the rat.