Mallinckrodt times GastroMark launch with ISMRM conference

Advanced Magnetics product used for bowel imaging

Mallinckrodt made its long-awaited entrance into the MRI contrast market this month with the introduction of GastroMark at the International Society of Magnetic Resonance in Medicine conference in Vancouver, British Columbia.

Sales of GastroMark commenced April 7, four months after Advanced Magnetics, its developer, secured product approval from the Food and Drug Administration (SCAN 12/18/96). Mallinckrodt is licensed to sell the MRI bowel marker in the U.S., Canada, and Mexico. It has been sold in Europe for several years by Guerbet under the trade name Lumirem.

GastroMark (ferumoxsil) is a silicon-coated superparamagnetic iron oxide, approved for administration to adults for MRI imaging of the upper GI tract. Its negative (black) appearance in the bowel during T1- or T2-weighted imaging is a key selling point, according to Keith Betkowski, Mallinckrodt's MRI market manager.

"It really does help delineate the bowel better than non-contrasted studies, and reduces ghosting artifacts," he said.

GastroMark is sold as a premixed oral suspension in 300-mL bottles that typically cost $25, Betkowski said. The minimum dose is 600 mL. It fills the stomach and small intestine 30 to 45 minutes after ingestion. The procedure can begin immediately, although optimal imaging occurs 30 minutes after the agent is ingested.

In two blinded clinical trials, 58% and 52% of the evaluators saw improvements in bowel marking and anatomical delineation in enhanced T1-weighted images of the upper GI tract. For T2-weighted images, 71% and 55% of the readers observed improvements in the two trials.

The presence or absence of mass lesions was examined for a subset of patients. In this group, GastroMark increased confidence when excluding the presence of masses in 31% and 41% of the patients, and it raised confidence in delineating the mass in 44% and 49%.

Betkowski is confident that GastroMark will not run into the problems with diarrhea that shortened the product life of Imagent GI, the first MRI contrast agent approved for the upper GI tract. Imagent's developer, Alliance Pharmaceutical of San Diego, stopped marketing the agent in 1994 (SCAN 9/28/94).

"GastroMark is an aqueous soluble solution rather than an oil-based solution, so it is not as slippery as Imagent and is not eliminated as quickly," he said.

In addition to GastroMark, Mallinckrodt is looking at other agents, such as extracellular and blood-pool agents. Optimark (Gd-DTPA-BMEA) is a gadolinium-based agent in phase III clinical trials.