DuPont Pharmaceuticals is preparing its U.S. launch of Definity, an ultrasound contrast agent that was cleared by the Food and Drug Administration in August.
In October, the North Billerica, MA-based firm will begin U.S. promotion of the agent for its approved indication -- left ventricular opacification and endocardial border definition in patients who are difficult to image with echocardiography, or whose results are suboptimal, according to Dave Pendleton, DuPont's senior brand director for Definity. DuPont's research showed that approximately 20% of echocardiograms are suboptimal or nondiagnostic.
"The left ventricle is the primary pumping chamber in the heart, and in terms of the ramifications of coronary artery disease, the effect on the left ventricle is of the most concern to the cardiologist as well as to the patient," said Dr. Peter Gardiner, vice president of medical affairs for DuPont's cardiovascular and imaging section. "It's the use of echo to evaluate left ventricular structure and wall motion that is important. That's where, in difficult-to-image patients, Definity comes in with a real advantage in its ability to provide clearer images to the physician."
Unlike other imaging agents, Definity is not blood-based. It is therefore less likely to cause allergic reactions, Gardiner said. DuPont's prescribing information notes that the agent is prepared in normal saline, and that the amount of product is adjusted appropriately for the method of delivery. Clinical trials demonstrated the product's ability to achieve successful opacification of the left ventricle using either bolus administration or continuous infusion, according to the company.
The persistence of opacification is about 3.4 minutes with a bolus of Definity, and about 7.2 minutes with intravenous infusion, Gardiner said. He said the bolus injection is followed by a saline flush to move the agent's microspheres from the peripheral vein in the arm to the cardiac circulation.
DuPont also initially applied for abdominal radiology applications in the U.S., but the FDA requested additional clinical trial data, according to DuPont spokesperson Lili Gordon. She said the company is continuing its evaluation of Definity in phase II and phase III studies for liver and kidney applications.
In Canada, however, Definity (vial for perflutren lipid microsphere injectable suspension) was approved in December for heart, liver, and kidney imaging. The approved cardiac indication is similar to that granted by the FDA, while the abdominal indication is for contrast-enhanced ultrasound imaging of the liver and kidneys in adult patients to improve the evaluation of pathology, according to the vendor.
Gardiner said DuPont's European application was formally withdrawn in the middle of last year in response to a request from for additional information. The company is assessing how to move forward in the European Union's approval process.
"We withdrew the EU application for Definity because we believe we had an opportunity to strengthen and resubmit our application with new data that could result in broader indications," Gordon said.
He declined to comment on how soon it will submit Definity for regulatory clearance in myocardial perfusion studies, an application widely viewed as key to the success of an echocardiography ultrasound agent.
"Myocardial perfusion is clearly another important area for echocardiography," Gardiner said. "It's very much a developing field with a lot of investigational work going on in the area of ultrasound
contrast in myocardial perfusion. We're involved in research in this area as well with Definity, but it's still at an early stage and not something we can comment on any further."
While acknowledging that perfusion imaging represents an important growth opportunity for echocardiography contrast agents, Pendleton said DuPont wants to initially focus on addressing the 20% of all echocardiograms that are suboptimal or nondiagnostic.
DuPont has not settled on a final price for Definity, and is waiting until it can finish totaling up research and other costs. Meanwhile, the firm is staffing a dedicated Definity sales organization, as well as a clinical associate organization, composed of mostly sonographers, Pendleton said. The clinical associates will perform a broad range of medical education and hands-on technical support for customers who start using Definity.
The firm's experience with its cardiac imaging agent Cardiolite reinforced the firm's belief that clinical and medical support for customers is crucial to the successful introduction of an imaging agent, Gardiner said.
"We intend to build on that with Definity by providing a group of sonographers who will work on an individual basis with physicians and sonographers at the sites, to make sure they understand how best to use the product, and how best to use the ultrasound equipment in conjunction with the product," he said.
Unlike the experience with Cardiolite, however, DuPont doesn't intend to license other companies to sell Definity, preferring to market the agent directly to end-users.
"It's such an easy preparation that we decided that it's much easier to deal directly with the end-user customers," Gardiner said. "That way, we can have that relationship directly and simplify the overall supply chain."
By Robert BruceAuntMinnie.com contributing editor
September 5, 2001
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