title: Comparison of Absorbents and Drugs for Internal Decorporation of Radiocesium: Advances of Polyvinyl Alcohol Hydrogel Microsphere Preparations Containing Magnetite and Prussian Blue.
abstract: Radiocesium nuclides, used as a gamma ray source in various types of industrial equipments and found in nuclear waste, are strictly controlled to avoid their leakage into the environment. When large amounts of radiocesium are accidentally incorporated into the human body, decorporation therapy should be considered. Although standard decorporation methods have been studied since the 1960s and were established in the 1970s with the drug Radiogardase(®) (a Prussian blue preparation), application of recent advances in pharmacokinetics and ethical standards could improve these methods. Here we designed a modern dosage form of hydrogel containing cesium-absorbents to alleviate intestinal mucosa irritation due to the cesium-binding capacity of the absorbents. The effectiveness of the dosage form on fecal excretion was confirmed by quantitative mouse experiments. The total cesium excretion rate of the crystal form (1.37±0.09) was improved by the hydrogel form (1.52±0.10) at the same dose of Prussian blue, with a longer gastrointestinal tract transit time. Using a mouse model, we compared the effects of several drugs on fecal and urinary excretion of internal cesium, without the use of absorbents. Only phenylephrine hydrochloride significantly enhanced cesium excretion (excretion rate of 1.17±0.08) via the urinary pathway, whereas none of the diuretic drugs tested had this effect. These findings indicate that modifying the dosage form of cesium absorbents is important for the decorporation of internal radiocesium contamination.
authors.affiliation: Internal Decorporation Research Team, Research Program for Radiation Medicine, Research Center for Radiation Emergency Medicine, National Institute of Radiological Sciences.
authors.forename: Izumi
authors.initials: I
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishihara
authors.forename: Haruko
authors.initials: H
authors.lastname: Yakumaru
authors.forename: Mika
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kazuko
authors.initials: K
authors.lastname: Yokochi
authors.forename: Katsushi
authors.initials: K
authors.lastname: Tajima
authors.forename: Makoto
authors.initials: M
authors.lastname: Akashi
mesh_terms: D000327:Adsorption; D000818:Animals; D000931:Antidotes / Q000494:pharmacology*; D002588:Cesium Radioisotopes / Q000493:pharmacokinetics*; D005295:Ferrocyanides / Q000494:pharmacology*; D052203:Ferrosoferric Oxide / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects; D008809:Mice, Inbred C3H; D008863:Microspheres; D011142:Polyvinyl Alcohol / Q000494:pharmacology*
chemical_list: D000931:Antidotes; D002588:Cesium Radioisotopes; D005295:Ferrocyanides; C062364:polyvinyl alcohol hydrogel; D011142:Polyvinyl Alcohol; C000170:ferric ferrocyanide; D052203:Ferrosoferric Oxide