In a similar vein: Fluosol-DA.

In a similar vein: Fluosol-DA

Perfluorochemicals are fluorine-containing compounds, many of which are able to carry large quantities of oxygen. Fluosol-DA, first developed in Japan, is a patented emulsion of two such perfluorochemical compounds, perfluorodecalin and perfluorotripropylamine. It is currently undergoing human clinical trials for a variety of potentially therapeutic uses. Among them:

As an "ischemic modifier' in conjunction with balloon angioplasty: Balloon angioplasty, in which a tiny balloon is inserted and temporarily inflated inside a coronary artery, has become a popular method of unclogging blood vessels that are responsible for bringing oxygen to the heart. During the procedure itself, however, blood flow to the heart is blocked, limiting the time allowed for the delicate operation. Fluosol is being used experimentally in animals to oxygenate the heart during this induced "ischemia,' or lack of oxygen.

It's hoped that the technique will allow physicians to leave the balloon inflated for longer periods, as longer inflation time is believed to make the vessel treatment more permanent.

"Fluosol has a very small particle size --much, much smaller than any red blood cell,' says George Groveman, of Alpha Therapeutic, which holds the U.S. license to manufacture and test Fluosol. "A Fluosol particle is about one-seventieth the size of a red blood cell,' which allows Fluosol to go "where the delivery of blood is either not possible or is submaximal.'

As a cancer therapy enhancer: Nearly all solid cancer tumors contain cells that are extremely low in oxygen--a property that makes them resistant to both radiation therapy and chemotherapy. "Both modes of therapy require high levels of intracellular oxygen to exert their maximum effect,' Groveman says, "so by oxygenating a tumor with Fluosol we are able to sensitize it to radiation or to chemotherapy.' Advanced clinical trials along these lines have been "very encouraging,' he says.

As a preventive of reperfusion injury: Due to a process called free-radical superoxidation, cells just behind a recently reopened clot are often injured with the first rush of oxygenated blood. But the damaging reaction is apparently catalyzed by white blood cells, and there is hope that an acellular oxygen carrier such as Fluosol may be useful as a reperfusion fluid immediately following clot-dissolving therapy.

As a cardioprotective agent during heart attack: Animal trials suggest that Fluosol may protect heart muscle if administered during a heart attack. "We're still looking at what kind of "cocktail' would be involved,' Groveman says. "But the dog trials that we've done suggest that you can salvage a third to two-thirds of that area of heart muscle that would have been infarcted [injured by lack of oxygen during a heart attack].'

In addition to these uses, some researchers believe that Fluosol may prove useful for keeping donor organs oxygenated while they are readied for transplant. And it may be an effective treatment for cerebral ischemia, in which an injury results in an interruption of oxygen flow to certain parts of the brain.

A Fluosol-like oxygen carrier may even get approval as a systemic "hemoglobin substitute' for patients with seriously low levels of the natural oxygen carrier. But clinical trials are difficult to perform on such seriously ill patients, Groveman says. So for now, the research emphasis is on "localized, focal ischemic events, as opposed to a generalized lack of oxygen.' As such, he says, "We expect it to be on the market sometime next year.'