Colloidal compositions with protective agents suitable for radioactive labeling

In a process wherein a dispersion of denatured aggregates of serum albumin to which tin is attached, suitable for radioactive labeling and use as a diagnostic agent is prepared and lyophilized and where the physical and chemical properties of said particles degrade during lyophilization or aging thereafter the improvement comprising additionally including in a sufficient amount in said dispersion as a protective agent a mixture of a polycarboxylic acid and a disaccharide or monosaccharide.

In a process wherein a dispersion of colloidal particles suitable for radioactive labeling and use as a diagnostic agent is prepared by (a) forming a dispersion containing a sulfur colloid by reacting in an aqueous medium a thiosulfate with a pharmaceutically acceptable acid (b) interacting a pharmaceutically acceptable stannous salt with the dispersion of (a), thereafter buffering the resulting dispersion, and (c) lyophilizing said dispersion and where the physical and chemical properties degrade during lyophilization or aging thereafter, the improvement comprising additionally including in said dispersion in a sufficient amount an amino acid as a protective agent to reduce degradation of the physical and chemical properties of the dispersion during lyophilization and aging thereafter.