Colloidal Zirconyl Phosphate-P-32. Preparation and Tissue Distribution Following I. V. Administration

Summary

1. Several technics of preparing stabilized sols of zirconyl phosphate-P-32 have been described using dextran, soluble starch, and glucose as suspending agents. All preparations exhibited good stability, small and uniform particle size, low solubility, and metabolic “inertness.” High concentrations of glucose have proved superior to all other suspending agents for the preparation of injectable zirconyl phosphate sols. 2. In experimental animals, zirconyl phosphate-P-32 was concentrated rapidly in the liver, spleen, and bone marrow, when given intravenously. In the rat, a marked depression of the leukocyte count was effected. The LD₅₀ for the rat was greater than 2 mc/kg but less than 1 mc kg in the rabbit. Combined urinary and fecal excretion of P-32 by the rat was 1.11 ± .16%/day. 3. In human leukemia patients the radiocolloid was localized principally in liver, spleen, and bone marrow. Other tissues as muscle, brain, skeleton, and reproductive organs exhibited little affinity for the colloid. 4. This radiocolloid may be used to advantage in the rather selective irradiation of the reticulo-endothelial system in the management of chronic leukemia and related blood diseases.