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By Jared A. Favole Of DOW JONES NEWSWIRES SILVER SPRING, Md. -(Dow Jones)- The benefits associated with Acusphere Inc.'s (ACUS) ultrasound heart-imaging agent are inconsistent and some of the risk signals are disturbing, a group of medical experts said Wednesday.
Acusphere, a specialty pharmaceutical company based in Watertown, Mass., is seeking U.S. Food and Drug Administration approval for Imagify to help identify blood-flow problems and coronary heart disease in patients with stable chest pain. The proposed drug belongs to a class of products called ultrasound heart-imaging agents. These agents, also called contrasting agents, enhance images of the heart.
Clinical studies with Acusphere suggest Imagify may result in acute inflammation and abnormally low blood pressure, the FDA said. Seventeen patients taking Imagify during clinical studies experienced adverse events that were serious enough to cause them to permanently stop taking the product. Such adverse events include vertigo and hypertension.
The drug was the topic of an FDA-sponsored panel meeting in Silver Spring. The FDA will take the panel's thoughts into consideration when it decides whether to approve the drug. Sixteen panel members said Imagify's benefits didn't justify the risks of the drug. One panel member abstained from voting.
Imagify, if approved, would likely be widely used as a diagnostic test to determine whether patients have blood-flow problems. It's potential wide use, coupled with safety concerns arising from clinical trials, was a sticking point with some FDA officials and panel members.
"We are particularly concerned about this drug because of its use as a screening tool," said Rafel Dwaine Rieves, director of the FDA's medical imaging division.
Panel members acknowledged that many patients who are screened for coronary heart disease have other complications, but some said risk signals in patients who took Imagify were troubling.
"There is some pretty disturbing signals" with Imagify, said panel member John Flack, a professor of medicine and physiology at Wayne State University in Detroit. He acknowledged, however, that more safety information was necessary to determine whether the risks with Imagify are more frequent than those associated with other ultrasound-imaging agents and other treatments.
Contrasting agents came under increased scrutiny last year after post-marketing reports associated several of the products with hundreds of adverse events, including more than a dozen deaths. These reports were associated with GE Healthcare's Optison and Lantheus Medical Imaging's Definity. GE Healthcare is a unit of General Electric Co (GE). Those reports prompted the FDA to update the drugs' labels in October with strong warnings.
Doctors have decried the warnings as too strong, saying they deter physicians from using the agents even though they help save lives. Doctors have argued that most of the adverse events reported to the FDA about Optison and Definity were the result of underlying problems with patients, not the drugs. Many patients who receive contrast agents are suffering from severe heart problems.
Rieves, of FDA, said he anticipates that Imagify's label, if the drug is approved, would carry a black-box warning similar to other contrast agents. Such a label is the agency's strongest and appears on the label in a black box.
Optison and Definity are "microbubble" contrast agents, meaning they consist of a gas core encased within a molecular shell. Imagify is a "microsphere" drug consisting of a mechanically rigid particle that contains pores filled with gas. The gas contained within the products enhances the acoustic signal of ultrasound waves and provides a contrast between the blood vessels and surrounding structures.
Acusphere said the inflexibility of Imagify allows physicians to see images of the heart for a longer period of time than microbubble agents. This increased time frame is essential for helping diagnose coronary artery disease, which if left untreated can lead to heart attacks.
-By Jared A. Favole, Dow Jones Newswires; 202-862-9207; jared.favole@dowjones.com
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Publié le 10 Décembre 2008 Copyright © 2008 Dowjones