Presentation Hydrogel formulation of Cs-absorbent and laxative drugs for enhancement of decorporation rate of internally contaminated radiocesium

Ishihara, Hiroshi  ,  Tanaka, Izumi  ,  Yakumaru, Haruko  ,  Tanaka, Mika  ,  Yokochi, Kazuko

Clinical decorporation procedure using Radiogardase to decrease body-burden of radiocesium caused by to the internal contamination accidents has been established in the last century. We aimed to improve the decorporation treatment to minimize stress of patients as the current tendency. The effects of several drugs were estimated by the measurement of the fecal and urinary excretion rates of radiocesium using mouse model. First, we examined the effect of pharmaceutical modification of the drug formulation of radiocesium-absorbents, because water-insoluble form of absorbents such as Prussian blue is sharp-pointed large crystal and may irritate the mucosa of gastro-intestinal (GI)-tract physically. Crystals of ferrous ferricyanides in the sizes of less than 1 micrometer were embedded in polyvinyl alcohol hydrogel with globular shap in the diameters from 10 to 50 micrometer. They were lyophilized for storage and hydrated just before administration. Though the rude crystal is rapidly excreted within 3h after the intrastomach administration, its hydrogel preparation elongates the retention time in GI-tract up to 6h, suggesting mitigation of irritation in mucosa by the formulation. Simultaneously, the excretion rate of internal radiocesium was increased by the use of the hydrogel formulation. Next, the effects of clinical drugs on the cesium excretion were examined in mouse. No diuretic drugs accelerated urinary excretion rate of internal radiocesium. In contrast, several drugs which has mild laxative action enhance intestinal excretion rate of internal radiocesium. These data show that decorporation rate of intestinal radiocesium can be enhanced by the procedure focusing on internal excretion rate, e.g. the simultaneous use of pharmaceutically formulated absorbents and laxatives.
15th International Congress of Radiation Research

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