Sodium bicarb use questioned.

When the body is in serious trouble--after a heart attack or duirng liver failure, for example -- the blood becomes acidic. And since acidic blood is life threatening, doctors commonly treat the condition by injecting a base, sodium bicarbonate.

"It seems intuitively reasonable that if you have acidosis, giving a base will make it better," says Allen I. Arieff of the University of California at San Francisco. But the effects of sodium bicarbonate have never been adequately tested in clinical experiments, and animal experiments show it may actually make the situation worse, he says. At the recent meeting of the American Society for Clinical Investigation (ASCI) in Washington, D.C., he described the ill effects of injecting sodium bicarb and suggested a substitute that has proved effective in animal and human trials -- another alkaline chemical called dichloracetate.

The acidity in acidosis comes from lactic acid, a "dead-end waste product," Arieff explains. The body usually can metabolize 10 times more lactic acid than its tissues can produce, except when there's not enough oxygen. Then the process fails and potentially lethal lactic acidosis results.

In previously published work, Arieff and his colleagues compared the effects of sodium bicarbonate, sodium chloride and no treatment in dogs made acidotic by limiting their oxygen intake. The sodium bicarb increased lactic acid concentrations, more than did sodium chloride or no treatment. The lactic acid increase led to lowered blood pH and bicarbonate levels -- the opposite of what was desired -- and hindered heart function. "Doing nothing was much better than giving bicarbonate," Arieff says.

At the ASCI meeting, Arieff described what happened when acidotic dogs were given dichloroacetate, which stimulates an enzyme involved in maintaining the proper acid-base balance. The chemical increased blood pH and bicarbonate levels, held lactic acid levels steady and improved heart function.

Paul Rosen, a clinical research associate at Abbott Laboratories in North Chicago, one of the major producers of sodium bicarbonate for acidosis, says, "There may be validity to what they're saying. Whether you can extrapolate to humans is another question. But I wouldn't want to throw away sodium bicarbonate as a treatment of metabolic acidosis."

At the University of Florida in Gainesville, Peter W. Stacpoole and his colleagues have begun limited human trials of dichloroacetate. "There's increasing evidence it [sodium bicarbonate] may not [always] be beneficial," says Stacpoole, "though it files in the face of years of experience. I think it's time to seriously re-evaluate the role of bicarbonate treatment in lactic acidosis."

Initial results with dichloracetate look promising, he says, but the larger controlled clinical trials that weren't done with sodium bicarbonate are needed for the new drug. "You could make the same kind of criticism about dichloroacetate as with sodium bicarbonate at this time," says Stacpoole. "Dichloroacetate is still an experimental drug."