Ferrioxamine

Ferrioxamine methanesulfonate is a paramagnetic contrast agent that has undergone phase I and phase II clinical trials for use as an IV and retrograde contrast agent for the kidneys, ureters and bladder. It is more stable than Gd-DTPA, though its relaxivity is somewhat less, as expected from it having 5 unpaired electrons, vs 7 unpaired electrons for Gd-DTPA. 80% is eliminated by renal excretion and 20% by hepatic excretion. Ferrioxamine undergoes renal excretion by glomerular filtration but is actively reabsorbed in the tubules. This results in a longer plasma half-life than Gd-DTPA (128 min. vs 20 min. in rats).

In clinical imaging the long plasma half-life allows enhancement of the kidneys for 60 minutes with little change in intensity. Significant improvement in detectability of lesions in the kidneys is demonstrated over unenhanced controls. Side effects include epigastric distress and transient burning at the injection site. Increase in serum iron levels and a transient elevation of serum liver enzymes (SGOT/SGPT) have been reported.