Dextran Sulfate: Confusion Continues

During the past year dextran sulfate has become one of the most widely used "underground" HIV treatments -- based on laboratory tests showing that the drug stopped HIV in the test tube, plus the fact that oral dextran sulfate has been used for other purposes for 20 years in Japan, where it is available without a prescription. (For background, see AIDS Treatment News #50, February 12 of last year.)

But despite the widespread use in Japan, there have long been questions of whether dextran sulfate is absorbed from the intestines into the bloodstream well enough to be effective.

Recently, new data has increased these doubts about the "bioavailability" of the drug. The new information has been widely reported in the press, beginning with a story in the February 19 Los Angeles Times.. But experts disagree on how certain or conclusive the new data is.

At least until recently it has not been possible to measure dextran sulfate levels in the bloodstream. So at first an indirect test was used. Six people took 1800 mg each of the drug, and then were given before and after measures of a blood-clotting parameter known to be affected by dextran sulfate. Later, a direct chemical test was devised. Both studies concluded that less than one percent of dextran sulfate taken orally was absorbed into the bloodstream.

All seem to agree that these findings cast doubt on dextran sulfate. But questions remain. Was a single dose of 1800 mg enough for the test? Could even a small amount absorbed be of some benefit -- especially if combined with AZT or other drugs? Is the new blood-level test accurate? Could the Japanese have been taking a useless drug for 20 years and not noticed? How do we explain the apparent benefit seen in some of the data collected by physicians whose patients are using dextran sulfate? And even if the drug is not absorbed into the bloodstream, might it still benefit some people by treating HIV infec- tion in the intestinal lining itself, by direct contact?

At this time, the case for oral dextran sulfate seems weak. But confusion remains because solid answers are not yet available. We hope that the clinical trials now in progress will be completed so that physicians can answer the bottom-line question: Does the drug help patients?

There has been some controversy about the early release of preliminary information on dextran sulfate absorption, before formal publication. We think it was right to tell people early. Final analysis and publication of the results may take months -- and meanwhile thousands of people are making vital decisions about their health care. They need the best information available. We hope that this controversy does not deter other scientists and officials from releasing unpublished results when there is an urgent need to do so.

For more information, see: the Los Angeles Times, February 19, 1989 (home edition), page 1; statement by Martin Delaney of Project Inform, to be published in PI Perspectives this month (415/558-9051 to be added to Project Inform's mailing list); and an investigative arti- cle by Tim Kingston to be published in Coming Up! newspaper in San Francisco, April 1989.