The Effect of Repeated Injections of ^99mTc-Antimony-Sulphide Colloid on the RES of the Rat — Histopathologic Study^[*]

Experiments on inbred albino rats were performed to test the effect of repeated administrations of ^99mTc-antimony sulphide colloid on the integrity of the RES. Experiments were carried out in two batches, one with the preformed colloid given in increasing doses, and the other with the labelled colloid in increasing doses. In all, 9 groups of animals including a control group were tested. Studies included: organ weights of liver, spleen, lungs and kidneys, histopatholo- gy, contact macroautoradiography, microautoradiography and ^99mTc activity distribution in organs. Results showed no macroscopic or microscopic evidence of tissue damage after repeated injections up to a total dose of 18 mCi ^99mTc, 142.2 mg PVP, and 693 μg Sb, given in 9 equivalent doses at one week intervals. It is concluded that repeated administrations of ^99mTc-antimony sulphide colloid for liver scintigraphy are safe.

Untersuchungen an Albinoratten wurden zur Feststellung der Wirkung wiederholter Injektionen von ^99mTc-Sb₂S₃-Kolloid auf die Integrität des RES durchgeführt. Insgesamt wurden 9 Tiergruppen in die Untersuchung einbezogen. Leber, Milz, Lungen und Nieren wurden gewogen; ferner wurden histopathologische, Kontakt-makroautoradiografische und microau- toradiografische Untersuchungen durchgeführt und die Organverteilung der ^99mTc-Aktivität gemessen. Die Ergebnisse zeigten keine makroskopischen oder mikroskopischen Beweise für einen Gewebeschaden nach wiederholten Injektionen bis zur Gesamtdosis von 18 mCi ^99mTc, 142,2 mg PVP und 693 μg Sb in 9 äquivalenten Dosen mit einem Intervall von 1 Woche. Daraus wird geschlossen, daß eine wiederholte Verabreichung von ^99mTc-Sb₂S₃-Kolloid zur Leberszintigraphie gefahrlos ist.

^* This paper is dedicated to Professor Dr. K. Scheer on the occasion of his 60^th birthday.

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