U.S. researchers say promising new medicines are headed to the market that can help overcome increasing resistance to some HIV therapies.

The annual Conference on Retroviruses and Opportunistic Infections in Los Angeles revealed several promising drugs -- including Merck & Co.'s MK-518, Pfizer Inc.'s maraviroc and Johnson & Johnson's TMC125 -- The Wall Street Journal reported.

The three drugs are heading for review by the Food and Drug Administration and could be on the market by the end of 2007, the newspaper said.

Doctors say tens of thousands of HIV patients in the United States are infected with viruses that have become resistant to at least one class of HIV drug. Some patients who have fought HIV for years have run through the roughly two dozen drugs available, the newspaper said.

Copyright 2007 by United Press International