Federal Health officials said yesterday the government has abandoned plans to market one of the AIDS drugs that it has under study.
Researchers found they could not manufacture the compound, called cyano-thymidine, using the process they devised. Instead, the process they tried created another, closely related chemical that the National Institutes of Health and other groups had already been studying, said Dr. Samuel Broder of the National Cancer Institute, one of the developers of the first useful drugs to treat acquired immune deficiency syndrome.
The chemical, which was produced unintentionally from the experiments, is called didehydro-thymidine.
The difference between the two substances, which both have promising chemical properties as potential AIDS drugs, is that the "cyano" compound was new and would probably have been patentable, while the other compound probably is not patentable.
The government sought to press forward on that drug to get a substance on the market to compete with the high-priced azidothymidine (AZT), whose trade name is Retrovir. A year's treatment of AZT can cost $10,000.
But the "didehydro" compound is not a newly synthesized compound. It was made some years ago for other uses, and is already being considered for testing as a potential AIDS drug.
The federal government had solicited proposals from companies interested in manufacturing the drug. Government officials, upset by the high price that Burroughs Wellcome Co. decided to charge for AZT, said they hoped a drug patented by the government could be marketed at a lower price.
In seeking proposals to manufacture other drugs, the government has also begun requiring that successful bidders "package, market, and distribute antiviral pharmaceutical products in a nationwide marketing system at a reasonable price," a condition that was not placed on AZT.
The whole group of drugs -- from AZT to didehydro-thymidine and a drug now in human trials, dideoxy-cytidine -- all operate in a roughly similar way. They interfere with the AIDS virus' ability to multiply. Theoretically they can stop the spread of the virus within the body, but do not wipe out the virus already present in cells.
Work on didehydro-thymidine is in the early stage. If development continues, it will be some time before tests of the drug on humans can be done, officials said.