Gadoxetic acid

Gadoxetic acid

Gadoxetic acid is a contrast agent used in magnetic resonance imaging (MRI), specifically in the imaging of the liver. It is marketed under the brand name Eovist in the United States and Primovist in Europe. Gadoxetic acid is part of a class of MRI contrast agents known as hepatobiliary agents, which are taken up by the liver and excreted into the bile, providing enhanced imaging of liver tissue and liver-related diseases.

Chemistry

Gadoxetic acid, chemically known as gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid, is a complex of gadolinium with a diethylenetriamine pentaacetic acid (DTPA) derivative. Gadolinium is a rare earth metal that acts as the active magnetic component, while the DTPA derivative provides stability to the complex and reduces the toxicity of the free gadolinium ion. The ethoxybenzyl group in gadoxetic acid is what allows for its hepatocyte-specific uptake.

Pharmacokinetics

After intravenous administration, gadoxetic acid is rapidly taken up by hepatocytes, making it particularly useful for imaging liver lesions and distinguishing between benign and malignant liver lesions. Approximately 50% of the administered dose is taken up by the liver and excreted into the bile, while the remaining 50% is eliminated unchanged through the kidneys. This dual excretion pathway is beneficial in patients with impaired renal function, as it reduces the risk of nephrogenic systemic fibrosis, a rare but serious complication associated with gadolinium-based contrast agents.

Clinical Applications

Gadoxetic acid-enhanced MRI is primarily used for the detection and characterization of liver lesions, including hepatocellular carcinoma, focal nodular hyperplasia, and hepatic adenomas. It is also useful in assessing liver function and in the preoperative evaluation of liver transplant candidates. The enhanced contrast provided by gadoxetic acid allows for better visualization of the liver's internal structure, making it easier to identify and differentiate between various types of liver lesions.

Safety and Side Effects

Gadoxetic acid is generally well tolerated, with most side effects being mild and transient. Common side effects include nausea, headache, and dizziness. As with all gadolinium-based contrast agents, there is a small risk of nephrogenic systemic fibrosis in patients with severe renal impairment. However, the risk is significantly lower with gadoxetic acid due to its dual excretion pathway. Patients with a known allergy to gadolinium-based contrast agents should avoid gadoxetic acid.

Conclusion

Gadoxetic acid is a valuable tool in the field of liver imaging, offering enhanced contrast and specificity for liver lesions. Its unique pharmacokinetic properties and safety profile make it a preferred choice for patients undergoing liver MRI.