Panel inclined to favor two MRI contrast agents

Two nonionic MRI contrast agents, Prohance and Omniscan, are inchingcloser to Food and Drug Administration approval. But despite afavorable review by the agency's medical imaging drugs advisorycommittee meeting last month, the agents are still nearly a yearaway from the open market.

"No formal vote was taken, due to lack of a quorum, butin both instances the committee was favorably disposed to thesetwo agents," said Leander B. Madoo, executive secretary forthe imaging drugs advisory committee.

The committee considered new drug application (NDA) data evaluatedby Dr. Hsien Ju, a medical officer in the FDA's division of medicalimaging. The data included results from phase three clinical trialsconducted by Squibb Diagnostics (Bristol-Myers Squibb) for Prohanceand by Sterling Drug (Sterling Winthrop) for Omniscan. Ju spentonly 20 minutes discussing each agent.

"That short amount of time for review is indicative thatthere weren't many questions about the agents," Madoo said.

Committee members did raise concerns about the lack of dosecalibration data in the studies, however, and noted that a phasefour study may be required either prior to or post-FDA approval.

A firm time line for approval was one of several details theadvisory committee discussed in closed session. Without elaboratingon that discussion, Madoo said the agency is interested in expeditingapproval, which could occur within a year.

"Just because things look good from a clinical standpointdoesn't mean that a few kinks don't need to be worked out, interms of labeling and production," he said.

Representatives from Sterling and Squibb would not commenton the committee meeting.

Only Berlex's Magnevist is currently FDA-approved for MR applications.Although not a nonionic, it is considered one of the safest agentsin both delayed as well as bolus injections.

Eventual approval of the two nonionic agents will mean competitionfor Magnevist in brain and spine studies. Clinical studies ofthese agents demonstrate that increased doses are possible withoutrisk of adverse effects.