Testing on blood substitute on hold

WASHINGTON — A Navy plan to test a blood substitute on civilian trauma victims should remain on hold, federal health advisers recommended Thursday, saying the experiment's risks outweigh its benefits.

The nonbinding vote appears to be the latest blow to the Navy, which repeatedly has sought Food and Drug Administration (FDA) approval to test the product, derived from cow blood, on roughly 1,100 trauma victims in emergency situations. It proposes doing so without obtaining the customary informed consent of patients.

Dr. Jay Epstein, director of the FDA's office of blood research and review, told panelists that trials done without consent must clear a higher hurdle than ordinary tests. The trials can't just minimize the harm that might befall participants but should promise them some benefit as well, he said.

The panelists later voted 11-8, with one abstention, that the experiment's potential benefits don't outweigh its risks. The FDA isn't required to follow the recommendations of its advisory committees, but it usually does.

If it does in this case, it would mark the fourth time since June 2005 that the FDA has blocked Hemopure trials from starting. Each time, it has cited safety concerns about using Hemopure as an experimental substitute for the saline fluids typically given in ambulances.

Researchers say blood substitutes can both counter a dangerous drop in blood pressure in bleeding victims and carry oxygen from the lungs to the body. Saline fluids can do the former but not the latter. While blood can do both, it has its own limitations. Unlike blood, blood substitutes theoretically could be stored for years and then used without concern for infection or blood type.

Hemopure's manufacturer, Biopure, based in Cambridge, Mass., contends that its benefits outweigh its risks, as does the Navy. A Navy official said the blood substitute could save lives in places such as Iraq, where 68 percent of the U.S. troops who die of trauma before reaching a hospital suffer severe bleeding.

"We urgently need an oxygen-carrying capability that does not require refrigeration, is universally compatible and can be readily administered in a field setting," said the Navy's deputy surgeon general, Rear Adm. John Mateczun.

The Navy wants to test Hemopure on civilians because the battlefield is too uncontrolled an environment.

In testimony Thursday, one critic said that the proposed trial is unethical and that the FDA's previous reasons for blocking the trial remain valid.

"Human subjects would be exposed to an unreasonable and significant risk," said Dr. Sidney Wolfe of the watchdog group Public Citizen.