Experimental Blood Substitutes Unsafe, Study Finds

MONDAY, April 28 (HealthDay News) -- Experimental hemoglobin-based blood substitutes boost the odds of death and heart attack for recipients, according to an exhaustive review of the data.

These products are not yet approved for use in the United States but have undergone extensive clinical testing.

The study, released early Monday by the Journal of the American Medical Association, has critics charging that the U.S. Food and Drug Administration failed to detect and act on a significant increase in heart attacks and deaths noted in trials of these laboratory-made blood substitutes.

That delay put participants in ongoing trials in jeopardy, they said.

"What I would like to see come out of this is a change in the rules about how the FDA handles data from clinical trials," said study co-author Dr. Charles Natanson, head of the anesthesia section of the U.S. National Institutes of Health's Clinical Center in Bethesda, Md.

"They should not be treated as trade secrets. The results should be made public in a short period of time," he said.

The report looked at data from 16 trials of five experimental artificial blood products, involving 3,711 patients. The researchers found an overall 30 percent increased risk of death and nearly triple the risk of heart attack for persons who got these products compared to those who did not.

Yet five trials of such products are still ongoing in eight countries outside the United States, and the FDA is considering a request for a trial here, the report's authors said.

An artificial blood product -- one with a longer shelf life and without the need for refrigeration required for human blood -- is a long-sought therapeutic goal. All the products described in the report are based on hemoglobin, the oxygen-carrying protein found in red blood.

The problem with such products is that "these hemoglobins do not have the protection of red blood cells," said study co-author Dr. Sidney Wolfe, director of the health research group at Washington, D.C.-based Public Citizen, an advocacy group that is often at odds with government agencies.

"Outside the cell, hemoglobin scavenges nitric oxide," Wolfe explained. "This causes constriction of arteries that is predictive of increased risk of heart attacks and organ damage."

Wolfe and Public Citizen initiated the inquiries that produced the report, starting in 2006. "We learned from the Federal Register that the FDA would hold an advisory committee meeting about a blood product," Wolfe said. "They decided to keep it secret. We sued the FDA, and they canceled the meeting because it was illegal."

Wolfe contacted Natanson, "because I knew he was on advisory committee of the FDA," and they began a search for information on hemoglobin-based blood substitutes. It was not easy to find, because neither the companies testing the products nor the FDA were forthcoming with information, Wolfe charged. Often, the FDA did not report on trial results, because they were regarded as trade secrets, he said.

The only information available in many cases came from press releases. In the case of one product, Polyheme, a report was not published until December, 2006, six years after the trial ended.

"It took a long amount of time, because a meta-analysis like this, if done appropriately, takes an enormous amount of energy and time," Natanson said.

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