HIV Digest	HIV Digest Archive

Twenty medicines are currently available in the United States to treat HIV infection. More are needed, however, because one-third to one-half of infected persons are unable to attain the goal of stopping viral growth using existing antiretrovirals.

Among the notable candidates are the following drugs:

Pharmasset's Reverset, a nucleoside reverse transcriptase inhibitor that can be taken orally once a day, does not damage mitochondria, and works on HIV that has evolved resistance to AZT, 3TC (lamivudine) and other medicines. It reduced HIV levels sharply-- to undetectable levels, in some cases-- in a brief, preliminary study of 30 HIV patients. Reverset could be on the market in three to four years.

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Schering D (SCH-D) blocks the CCR5 receptor on human cells. To penetrate a human cell, HIV must attach itself to CCR5 and to another receptor. If the receptor is blocked, in this instance by SCH-D, HIV cannot enter. In a study of 48 patients who took the pill for two weeks, it suppressed HIV's growth. A larger, longer study will be undertaken this spring, said a Schering-Plough researcher.

Bristol-Myers Squibb's BMS-488043 prevents a structure on HIV's surface-- gp120-- from attaching to the human cell's CD4 receptor-- a different target from other drugs.

Two compounds made by AnorMED of British Columbia have yet to be tested in humans but have blocked infection in lab tests when used together. One blocks the CCR5 receptor and the other blocks a different receptor, CXCR4.

Koronis Pharmaceuticals' SN1212 forces HIV's gene-replicating machinery to make so many mistakes that HIV ceases to be a viable entity. Lab tests have been unable to find or induce any HIV strains capable of resisting SN1212's action. However, researchers must determine that it works in humans and is not harmful.

Panacos Pharmaceuticals' PA-457 is dubbed a "maturation inhibitor." It blocks a step late in HIV's replication cycle when new copies are packaged for export out of the cell and is the only drug to act on this step in the cycle. FDA has given approval to try the drug in a few healthy people. If that trial goes well, it will be given to about 60 HIV-infected people this summer. While most antiretrovirals are synthesized from scratch, PA-457 is a natural product: It is made from betulinic acid, which is found in the bark of birch and plane trees.

Editor's Note: from the Washington Post