Abdominal agent could take Squibb into ultrasound

Bristol-Myers Squibb hopes the secret to unlocking the potentiallyhuge ultrasound contrast market lies in a derivative of a materialas rare as the common household plant. This month the companyrevealed the details of its licensing and manufacturing agreementfor SonoRx, a cellulose-based oral ultrasound contrast agent forabdominal applications.

BMS acquired U.S. rights to market and manufacture SonoRx fromImaRx, the Tucson, AZ-based firm that discovered SonoRx. The companiesare negotiating an agreement on worldwide rights.

SonoRx will submit an investigational new drug (IND) applicationthis year, and clinical trials are expected to be completed in1994. The product is not in phase three clinical trials as reportedin the last issue of SCAN (2/24/93).

SonoRx was developed by Dr. Evan C. Unger and Dr. Guan Li Wufor ImaRx. Dr. Pamela Lund, a radiologist at the University ofArizona, performed the initial clinical evaluation.

BMS executives see SonoRx as a cost-effective product witha potentially huge base of applications.

"There is a very large base of abdominal ultrasound proceduresthat are done," said Brian Gallagher, vice president of strategicproduct planning in diagnostics for BMS. "For many peoplewith undescribed abdominal pain, the first line of imaging isan ultrasound procedure."

The problem is that stomach gas often causes shadow artifactsthat reduce the effectiveness of an ultrasound scan. SonoRx eliminatesartifacts by absorbing and displacing stomach gas and allows clearvisualization of abdominal organs, such as the liver, pancreasand duodenum. SonoRx also distends the gastrointestinal tract,allowing better visualization.

SonoRx is taken orally 10 to 30 minutes before an examination.The product uses a proprietary formulation of simethicone-coatedcellulose that is more like a food product than a drug, Gallaghersaid. It has been well-tolerated in human studies at the Universityof Arizona, he said.

This is not the first time a fairly commonplace oral intestinaldrug has displayed effectiveness as a contrast agent. Researchersat the University of Alabama at Birmingham have used Kaopectateas a contrast agent in MRI abdominal imaging due to its motion-calmingproperties in the GI tract (SCAN 10/12/88).

ImaRx and BMS are optimistic that the results of the Universityof Arizona studies will be replicated in phase three trials, andthat SonoRx will avoid difficulties similar to those encounteredby Albunex, a cardiac ultrasound contrast agent. Commercial releaseof Albunex was delayed after the Food and Drug Administrationasked its developer, Molecular Biosystems (MBI) of San Diego,for additional data for the product's pre-market approval application(SCAN 12/2/92).

MBI is also developing an abdominal ultrasound imaging agentthat could become a competitor to SonoRx.

Another potential competitor to SonoRx is even more cost-effective--water.Sonographers sometimes use water to distend the GI tract and displacegas. But the images produced using SonoRx were superior to thoseusing water in the University of Arizona studies, Gallagher said.

By improving the effectiveness of ultrasound exams, SonoRxwill reduce the need to send patients for follow-up scans usingother imaging modalities. This will help contain health-care costs,Gallagher said, and fits with the general trend toward expandingultrasound applications.

The pricing structure of SonoRx will also be cost-effective,he said.

"With reimbursement being what it is for ultrasound procedures,we know that the cost of the drug cannot be more than a smallpercentage of the procedural cost," Gallagher said.

SonoRx is not the first product licensed between the companies.BMS licensed a gastrointestinal MRI agent from ImaRx in 1991.That product is also in development.

BMS has been working on its own ultrasound contrast agents,but signed the agreement with ImaRx because of the advanced stageof the company's work.

"(We decided) that the easiest thing would be to licensefrom them, rather than try to figure out how to compete with themor get around them," Gallagher said. "We believe ultrasoundcontrast agents are going to play a role (in the future of healthcare), and we very much want to participate in that."