Rationale and objectives: The authors compare in vivo transmetallation of three magnetic resonance contrast agents in humans in terms of their kinetic stability.
Methods: Blood and urine samples were taken before and after the intravenous injection of gadolinium (Gd)-HP-DO3A, Gd-DTPA, or Gd-DTPA-BMA at 0.1 mmol/kg to healthy volunteers. Serum and urine were assayed for zinc, copper, and Gd, using inductively coupled plasma atomic emission spectrometer.
Results: Gadolinium-DTPA-BMA caused the highest increase in zinc excretion among the three agents. Gadolinium-HP-DO3A did not cause a significant increase in zinc excretion. In serum, although Gd-DTPA-BMA exhibited a decrease in zinc concentration, the difference between the drugs was not statistically significant.
Conclusions: The difference in observed zinc excretion among the chelates studied reflects in vivo transmetallation of the magnetic resonance contrast media and correlates with the respective kinetic inertia for transmetallation, rather than thermodynamic stability constants. Gadolinium-HP-DO3A was found to be the most kinetically inert among the three drugs tested.