Distribution of Thiourea following Intravenous and Oral Administration to Rats

概要

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^<14>C-Thiourea was given by intravenous or oral administration at low dose (100 μCi/0.16 mg/kg) or high dose (100 μCi/160 mg/kg) to rats, then plasma levels were determined and whole-body autoradiography was carried out. The gel filtration on Sephadex G-10 of plasma obtained following intravenous administration of ^<14>C-thiourea showed that the radioactive label was covalently bound to macromolecular fractions such as protein or peptide. Plasma levels of radioactivity due to unchanged thiourea and the tissue distribution patterns of radioactivity following intravenous administration of ^<14>C-thiourea were considerably different after a low dose and a high dose. The elimination of thiourea from plasma in the case of high dose (t_<1/2β> ; 7.0 h) was greatly delayed as compared with that after the low dose (t_<1/2β> ; 0.69 h). The whole-body autoradiograms indicated that, at low dose, very high radioactivity was presented in the lung, thymus and Harder's gland at 60 min following intravenous administration, whereas when the high dose was administered the radioactivity was distributed almost homogeneously throughout the body. The remarkable dose dependency in thiourea distribution might be brought about by the saturation of irreversible covalent binding sites of plasma and tissue macromolecules in the case of high dose administration.
公益社団法人日本薬学会の論文
1982-09-25