Gadoteric acid Other names: Gd-DOTA

Gadoteric acid has paramagnetic properties allowing MRI contrast enhancement. It has no specific pharmacodynamic activity and is biologically very inert.

Following intravenous injection, gadoteric acid is mainly distributed in the extracellular fluid. It is not bound to plasma albumin.

In patients with normal renal function, the plasma half-life is about 90 minutes. Gadoteric acid is eliminated in unchanged form by glomerular filtration.

Plasma clearance is delayed in patients with impaired renal function.

A small amount of gadoteric acid is excreted in breast milk and crosses the placenta.

The current evidence suggests that gadolinium may accumulate in the brain after repeated administration of gadolinium based contrast agents (GBCAs) although the exact mechanism of gadolinium passage into the brain has not been established.

Non-clinical data reveal no special hazard for humans, based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, or toxicity to reproduction.

In acute toxicity studies of intravenous gadoteric acid in mice and rats, adverse effects (seizures, transient respiratory disorders) were only reported at doses much higher than those used in man.

Administration of gadoteric acid at daily doses of up to 15 times the recommended dose in clinical practice and for 28 days did not induce any marked effect apart from reversible vacuolization of renal proximal tubule cells.

Animal studies showed negligible (less than 1% of the administered dose) secretion of gadoteric acid in maternal milk.

No teratogenic effect was demonstrated in rats and rabbits.

No mutagenic effect was demonstrated on the reagent systems used.

Recent studies conducted in healthy rats injected repeatedly with linear or macrocyclic GBCAs demonstrated that linear agents were associated with progressive and persistent T1-weighed hyperintensity on MRI in the deep cerebellar nuclei (DCN). Signal enhancement in the globus pallidus (GP) could not be seen in the animals. No changes in signal intensities in either DCN or GP were observed for the macrocyclic GBCAs.

Quantitative results using mass spectrometry demonstrated that the total gadolinium concentrations were significantly higher with the linear GBCAs than with the macrocyclic GBCAs. These studies reported no abnormal behavioural changes suggestive of neurological toxicity.