Biochemical characterization of x-ray contrast media.

RATIONALE AND OBJECTIVES: Eleven ionic and nonionic contrast media were compared in parallel regarding their effects on various biochemical parameters in vitro. Partition coefficient, protein binding, release of histamine, hemolysis inhibition and complement activation were determined as well as inhibition of various enzymes. Additionally, incompatibilities between contrast media and intravascular drugs that often are coadministered were determined. METHODS: Partition coefficients were determined in the system n-butanol/water by spectrophotometry. Protein binding was measured by equilibrium dialysis. Histamine release from rat peritoneal mast cells was measured by radioassay. Hemolysis inhibition and complement activation was determined in beagle dog serum using antibody-coated sheep erythrocytes. The inhibition of enzyme systems was measured photometrically. Incompatibility with coadministered drugs was registered by appearance of precipitations. RESULTS: Hydrophilicity as determined by partition coefficients was highest for iotrolan and lowest for iotetrol. Protein binding ranged from practically zero for most substances to 14% for ioxaglate. Histamine release was highest for diatrizoate (77% at 100 mg I/mL) and lowest for iodixanol (1%). Complement activation at 100 mg I/mL ranged from 0% (diatrizoate, iopamidol) to 77% (iopentol). The inhibition of the enzyme systems urokinase, streptokinase, collagenase, tissue plasminogen activator, and lysozyme was lowest for the nonionic dimers. CONCLUSIONS: All compounds influenced the parameters tested. However, the degree of interaction was different. Although there was no significant correlation between hydrophilicity (partition coefficient) or osmolality and the tested parameters, nonionic dimers seemed to be superior to nonionic monomers. The reason might lie in reduced chemotoxicity of this class of contrast media.

Stability of doxorubicin combined with Radioselectan, a contrast agent, for chemoembolization.

OBJECTIVE: To assess the stability of doxorubicin combined with Radioselectan. METHODS: Solutions of doxorubicin 5 mg/mL were prepared from commercially available 50 mg powder with 10 mL of Radioselectan. They were stored in glass syringes at 4, 25 and 45 degrees C. The concentrations of doxorubicin were determined using a stability-indicating high-performance liquid chromatography method. The initial and final pHs of solutions were compared. The times (t90) needed for doxorubicin to fall to 90% of its initial concentration were calculated by a linear regression analysis. RESULTS: The t90 [95% confidence limits] were 79 [75-83], 56 [53-59] and 22 [21-23] hours for the solutions stored at 4, 25 and 40 degrees C respectively. The initial pH of the solutions stored at 4, 25 and 40 degrees C were 6.52, 6.50 and 6.51 respectively. The final pH of solutions stored at 25 and 40 degrees C decreased significantly by 0.3 and 0.9 respectively. No change of pH solution stored at 4 degrees C was observed. CONCLUSION: Doxorubicin combined with Radioselectan stored at room temperature is stable for 48 h.