Gadopentetic acid

Gadopentetic acid

Clinical data
AHFS/Drugs.com	Consumer Drug Information
Pharmacokinetic data
Biological half-life	Distribution half life 12 minutes, elimination half 100 minutes
Identifiers
CAS Number	86050-77-3 Y
ATC code	V08CA01 (WHO)
PubChem	CID: 55466
DrugBank	DB00789 Y
ChemSpider	50087 Y
UNII	RH248G8V27 Y
KEGG	D01707 Y
ChEBI	CHEBI:31797 Y
ChEMBL	CHEMBL1200431 N
Chemical data
Formula	C14H18GdN3O10
Molecular mass	545.56 g·mol−1
SMILES [Gd+3].[O-]C(=O)CN(CCN(CC(=O)O)CC([O-])=O)CCN(CC([O-])=O)CC(=O)O.O[C@H]([C@@H](O)CNC)[C@H](O)[C@H](O)CO.O[C@@H](CNC)[C@@H](O)[C@H](O)[C@H](O)CO
InChI InChI=1S/C14H23N3O10.2C7H17NO5.Gd/c18-10(19)5-15(1-3-16(6-11(20)21)7-12(22)23)2-4-17(8-13(24)25)9-14(26)27;2*1-8-2-4(10)6(12)7(13)5(11)3-9;/h1-9H2,(H,18,19)(H,20,21)(H,22,23)(H,24,25)(H,26,27);2*4-13H,2-3H2,1H3;/q;;;+3/p-3/t;2*4-,5+,6+,7+;/m.00./s1 Y Key:LGMLJQFQKXPRGA-VPVMAENOSA-K Y
NY (what is this?)  (verify)

Gadopentetic acid is one of the trade names for a gadolinium-based MRI contrast agent, usually administered as a salt of a complex of gadolinium with DTPA (diethylenetriaminepentacetate) with the chemical formula A₂[Gd(DTPA)(H₂O)]; when cation A is the protonated form of the amino sugar meglumine the salt goes under the name "gadopentetate dimeglumine". It was described in 1981 and introduced as the first MRI contrast agent in 1987. It is used to assist imaging of blood vessels and of inflamed or diseased tissue where the blood vessels become "leaky". It is often used when viewing intracranial lesions with abnormal vascularity or abnormalities in the blood–brain barrier. It is usually injected intravenously. Gd-DTPA is classed as an acyclic, ionic gadolinium contrast medium. Its paramagnetic property reduces the T1 relaxation time (and to some extent the T2 and T2* relaxation times) in NMR, which is the source of its clinical utility.

A bottle of Magnevist contrast agent.

Marketed as Magnevist by Bayer Schering Pharma, it was the first intravenous contrast agent to become available for clinical use, and is in widespread use around the world. Similar contrast agents are Magnetol manufactured by Soreq ,Dotarem (gadoterate) Guerbet, MultiHance (gadobenate dimeglumine) and ProHance (gadoteridol) manufactured by Bracco, Omniscan (gadodiamide) manufactured by GE Healthcare, and OptiMARK (gadoversetamide) manufactured by Mallinckrodt.

Gadolinium based agents may cause a toxic reaction known as nephrogenic systemic fibrosis (NSF) in patients with severe kidney problems.

Compared to other gadolinium-based MRI contrast agents, Gadopentetate dimeglumine (Gd-DTPA2-) chelates allow delayed Gadolinium-enhanced Magnetic Resonance of Cartilage (dGEMRIC). The unique charge characteristic of this complex allows researchers to inversely measure spin-lattice relaxation times as they are related to the concentration of proteoglycan aggregates and charged glycosaminoglycan side chains in articular cartilage.

Chemical structure and mode of action

In the complex of Gd³⁺ and DTPA⁵⁻ the gadolinium ion is 9-coordinate, surrounded by the 3 nitrogen atoms and 5 oxygen atoms from the carboxylate groups. The ninth coordination site is occupied by a water molecule. This water molecule is labile and exchanges rapidly with water molecules in the immediate vicinity of the gadolinium complex. The gadolinium ion has 7 unpaired electrons with parallel spins and is strongly paramagnetic with an ⁸S electronic ground state. The relaxation time of the water molecules is affected by their intermittent binding to the paramagnetic centre. This alters their MRI properties and enables contrast enhancement to be achieved.

External links

• Bayer Healthcare Pharmaceuticals page on Magnevist (for US)
• Bayer Schering Pharma global Magnevist Website