Experimental study of DOTA-gadolinium. Pharmacokinetics and pharmacologic properties

Pharmacokinetic and acute-toxicity studies of Gd-DOTA meglumine (Mgl) were evaluated in various animals and compared with those of Gd-DTPA Mgl. The agents were injected intravenously at two dosages: 0.1 or 0.5 mmol/kg. Various organs and tissues were removed at specified times after injection and assayed for gadolinium (Gd) concentration. The two complexes behave in an identical fashion in their short-term biodistribution and excretion. The very rapid distribution in the body (except in the brain) and the high clearance from blood are due to an extravascular distribution. The small distribution volume and the very high hydrophilicity account for its extracellular localization. There is no accumulation within any organ. Rapid disappearance, short half-life, size, and hydrophilicity of these molecules are in agreement with urinary elimination by free glomerular filtration. Whatever the species or the salt used, Gd-DOTA appears safer in its acute toxicity than Gd-DTPA with an 85% higher safety factor. These results can be explained by the greater stability of Gd-DOTA (very slow kinetics of dissociation and greater specificity of DOTA than DTPA for gadolinium), and the lower osmolality of DOTA than DTPA. The pharmacokinetic characteristics and the very low toxicity of Gd-DOTA Mgl may prove its suitability for intravenous or oral administration in humans.