Abbott's Protease Inhibitor

Abbott Laboratories' protease inhibitor ABT-538 can prevent 99% of HIV replication and can reduce viral load in the blood by 70%-99%, according to data presented at the 2nd National Congress on Human Retroviruses and Related Infections (see also story above).

In addition, after taking the drug for three months, patients experienced an increase in CD4 cell counts of 100 or more per mm3. With most reverse transcriptase inhibitors, the increase at this point is usually around 30-35 cells/mm3, noted John Leonard, Abbott's director of protease inhibitor studies. He said the company is very optimistic about the drug, despite problems such as rapid emergence of resistance to this type of drug.

Merck & Co's protease inhibitor, L524, has produced similar results in early clinical testing, but a company spokesman was more cautious about the prospects for this drug, noting that it is still very early.