Gadobutrol (API)

About This Product

Gadobutrol, also known as Gd-BT-DO3A, is the gadolinium(III) complex of a DO3A macrocycle carrying a trihydroxybutyl side chain, with the formula C18H31GdN4O9, a molecular weight of 604.7 and CAS number 770691-21-9. It is a white to off-white solid that dissolves to give a clear solution, and it is the active ingredient of a widely used MRI contrast medium. Gadolinium shortens the relaxation time of nearby water protons, brightening tissue on a magnetic resonance image, but the free Gd3+ ion is toxic and must stay locked in its ligand for the whole time it is in the body. Macrocyclic agents such as gadobutrol hold the metal inside a pre-organised ring and release it far more slowly than open-chain agents, which is why, after the 2017 European review of gadolinium retention, macrocyclic agents became the standard for most uses. That is also why free gadolinium is the critical limit in this specification, held to 0.0003 percent, alongside chloride, heavy metals, and individual and total impurities. The side chain carries two stereocentres with a fixed relative configuration and the substance is racemic, so specific rotation is specified close to zero, between −0.05° and +0.05°, with the pH of solution at 5.2 to 6.2 and water up to 7.0 percent. It is used in formulating intravenous MRI contrast media for central nervous system, body and vascular imaging, and in pharmaceutical development. Bio Green Chem supplies gadobutrol to specification on appearance, solution clarity, specific rotation, water, pH, free gadolinium, chloride, heavy metals, related substances and assay, packed in fibre drums or bags. It is supplied for pharmaceutical manufacture, and regulatory documentation for the intended market is confirmed at enquiry.