Gadodiamide Hydrate (Omniscan), a nonionic Gd3+ chelate, is frequently injected i.v. into magnetic resonance imaging (MRI) to enhance contrast.

Gadodiamide results in half-life of 18, 38, and 75 minutes in rats, rabbits, and monkeys, respectively. Gadodiamide is shown to be excreted rapidly, primarily through the kidneys. [1] Gadodiamide, when administered i.v. as gadodiamide injection at a dosage of 0.3 mmol/kg, is stable in vivo and that the very major part of the dose (> 99%) is excreted in urine as an unchanged complex. [2] Gadodiamide produces focal and generalized myoclonus over several hours. Gadodiamide itself produces lesions in the central cerebellar regions resembling in character and severity those produced by the gadodiamide formulation, but not others. [3] Gadodiamide travels quickly throughout the ventricular system from the lateral ventricular site of injection to the fourth ventricle and foramina of Luschka and Magendie within 2 min. [4] Gadodiamide results in transient but statistically significant decreases in aortic pressure, left ventricular pressure, indices of left ventricular contractility and relaxation, and systemic and pulmonary vascular resistance, and increases in aortic blood flow in anesthetized dogs. Gadodiamide injection produces less severe alterations in hemodynamics than gadopentetate dimeglumine. [5]