In a new approach called phenotypic resistance testing, doctors can check the virus against all of the standard drugs to see which ones can kill it, then use the results to tailor their strategy. Understanding virus resistance is especially important when putting together new drug combinations after the initial drug cocktail fails to wipe out all visible signs of the virus. Doctors have 15 AIDS drugs to pick from, and the choice often amounts to an educated guess. Mass. He described the results Monday in San Francisco at the 7th Conference on Retroviruses and Opportunistic Infections. The test was developed by Virco N.M., a European biotechnology company that financed the study with Glaxo Wellcome Inc., the pharmaceutical company.
Doctors say an advantage of phenotypic testing is the simplicity of the results.
We monitor to see how well it grows. If it stops growing, that drug works. It's that simple. Doctors say that trying to understand how well drugs will work by analyzing viral genes can be daunting when the virus is resistant to several drugs. Sometimes resistance to one pill can help the virus withstand another, even though it does not specifically have resistance to that medicine.