Absorption, Disposition, and Excretion of 3H-Mineral Oil in Rats

Abstract

Thie fate in rats of 3 H-mineral oil was studied after both oral and i.p. administrations. Five hours following a single oral dose of 0.66 ml. of 3 H-mineral oil/Kg. about 1.5 per cent of the dose had been absorbed unchanged, and an additional 1.5 per cent of the dose was found in the carcasses as 3 H-nonmineral oil substances. The 3 H-mineral oil concentration in the carcasses decreased at first rapidly to 0.3 per cent within 2 days post-treatment, and much more slowly, thereafter, to 0.1 per cent of the amount administered by day 21. The absorption and excretion of mineral oil after chronic administration orally was similar to the absorption and excretion after a single dose. The physiologic disposition of the drug, 5 hr. after an oral dose, indicated that the liver, fat, kidney, brain, spleen, and carcass contained 3 H-mineral oil. After the i.p. administration of labeled mineral oil, it was excreted very slowly; 11 per cent was found in the feces during the first 8 days post-treatment; only trace quantities were found in the urine. The identity of the mineral oil following oral administration that had been isolated from tissues and excreta was made on the basis of thin-layer chromatography of tissue extracts. The similarity of the physical properties of the extracts of animals that had received mineral oil, i.p. or P.o., supported the view that it was mineral oil that had passed through the walls of the gut. The nonmineral oil nature of the substances containing 3 H after the administration of 3 H-water indicated that other substances were not mimicking 3 H-mineral oil in the assay. 3 H-mineral oil was shown to have exchanged 3 H with other substances. Metabolism of 3 H-mineral oil to more polar substances may also have occurred. The incorporation in the oil of dioctyl sodium sulfosuccinate, an emulsifying agent, tended to increase the amount of 3 H-mineral oil absorbed.