Compatibility and stability of non-ionic iodinated contrast media in peritoneal dialysis solution and safe practice considerations for CT peritoneography

BACKGROUND: Computerised tomographic (CT) peritoneography is performed on peritoneal dialysis (PD) patients to identify peritoneal boundary defects, dialysate maldistributions and loculated fluid collections. Iodinated contrast media are added to dialysate and infused through the dialysis catheter, and CT images are obtained. Chemical compatibility of contrast media with dialysis solutions has not been studied. In some institutions, pharmacists charged with oversight of compounded sterile preparations have placed a moratorium on the use of contrast media-dialysate mixtures until compatibility data become available. This study was undertaken to examine the compatibility of non-ionic iodinated contrast agents added to PD solution for the performance of CT peritoneography. METHODS: 100 mL of three non-ionic iodinated contrast agents, iopamidol 370 mgI/mL, iohexol 300 mgI/mL and iodixanol 320 mgI/mL, were mixed with 2 L 1.5% dextrose PD solution and stored at 2-8°C, 25°C and 40°C. Observations at predefined intervals were made over 5 days for visual appearance, turbidity, pH, drug concentration and chemical degradation. RESULTS: Iopamidol, iohexol and iodixanol were stable for 5 days under study conditions. The contrast-dialysate mixture remained clear and colourless, no turbidity changes observed, pH and drug concentrations were stable and no increase in existing impurities or new impurities were detected. CONCLUSIONS: The addition of commonly used non-ionic iodinated contrast agents to 1.5% dextrose dialysis solution is chemically stable, meeting the criteria set forth in the standards and guidelines of the US Pharmacopeia and the Institute of Safe Medication Practices. A protocol for performing CT peritoneography is recommended herein to facilitate patient safety and diagnostic reliability of the imaging study.