Clearance of gadolinium chelates by hemodialysis: An in vitro study

Although the gadolinium (Gd)-chelates currently approved for clinical use in the United States are considered “readily dialyzable,” the actual clearance rates have not been published. The purpose of this study was to establish in vitro dialysis clearance rates of Gd-chelates to develop rational strategies for removing the agents with dialysis. Three agents, Gd-diethylenetriaminopentaacetic acid (Gd-DTPA), Gd-HP-DO3A and Gd-DTPA-BMA were diluted separately in plasma and saline and were dialyzed by using a clinical dialyzer unit with a commercially available capillary filter at rates of 0-300 cc/min. Predialyzer and postdialyzer concentrations were determined by inductively coupled atomic emission photometry. Urea and creatinine clearance rates also were determined. The clearance rate for Gd-chelates were considerably lower than that of urea and cnatinine, which are generally considered benchmarks of dialysis efficiency. At 300 cc/min flow rates, the clearances were (clearance in cubic centimeters per minute with 95% con5dence interval): Gd-DTPA-74 cc/min (68-80 cc/ a) S-HP-DO3A 67 cc/min (63-71cc/min); and Gd- DTPA-BMA 67 cc/min (63-7lcc/min). In comparison, urea and creatinine were 180 cc/min (178-181 cc/ mh) and 142 cc/& (124131 cc/min). respectively. There was no difference between clearance rates of Gd-chelates in saline and plasma. implying there was no protein binding. By using a first order kinetic model of dialysis time, more than 12.2 to 14.7 hours of dialysis would be necessary to remove 97% of the injected dose of Gd-chelate. In conclusion, Gd-chelates are dialyzable and 97% elimination is predicted after 12-14.7 hours of dialysis, depending on the chelate used. Consequently, Gd-based contrast agents can be used in dialysis patients without modification to most maintenance dialysis schedules.