(Gadolite® oral Suspension) An oral paramagnetic MRI contrast agent to enhance delineation of the bowel. Zeolites are hydrated aluminosilicates with large holes that can provide a temporary home for guest molecules like gadolinium. Zeolites modified with Gd (III) are effective positive MRI contrast agents for gastrointestinal application.

An oral suspension of synthetic crystalline aqueous orange-flavored MRI contrast agent to enhance delineation of the bowel. Gadolite contains gadolinium, a lanthanide metal with paramagnetic characteristics. The toxic Gd is bound to become inert, along with water, inside a zeolite crystalline lattice structure. Gadolite gives a bright signal, and provides improved definition of the gastrointestinal tract from adjacent tissues.
Pharmacyclics receives an approvable letter from the FDA for Gadolite® Oral Suspension and in the United Kingdom an European marketing agreement signed with E-Z-Em, Ltd. in Dec. 1996.

Paramagnetic substances, for example Gd-DTPA solutions, are used as MRI oral contrast agents in gastrointestinal imaging to depict the lumen of the digestive organs. Different Gd-DTPA solutions or zeolites containing gadolinium can be used e.g., for diagnosis of delayed gastric emptying, diagnosis of Crohn's disease etc.
Low concentrations of gastrointestinal paramagnetic contrast agents cause a reduction in T1 relaxation time; consequently, these agents act on T1 weighted images by increasing the signal intensity of the bowel lumen. High concentrations cause T2 shortening by decreasing the signal, similar to superparamagnetic iron oxide. Gd-DTPA chelates are unstable at the low pH in the stomach, therefore buffering is necessary for oral use.

See also Gadopentetate Gastrointestinal, Gadolinium Zeolite, Negative Oral Contrast Agents, Gastrointestinal Superparamagnetic Contrast Agents, and Ferric ammonium citrate.