Test for Mitochondrial Damage Caused by Antiretroviral Drugs May Help HIV Patients Avoid Side Effects

A blood test to detect mitochondrial damage caused by antiretroviral drugs may help doctors switch HIV patients' medications before the onset of drug-related side effects, the Canadian Press/Globe and Mail reports. The test, developed by a team of researchers led by Dr. Julio Montaner of the British Columbia Center for Excellence in HIV/AIDS at the University of British Columbia in Vancouver, determines the level of mitochondrial DNA circulating in a patient's bloodstream. Mitochondria are cell sub-structures responsible for turning glucose byproducts into energy (Canadian Press/Globe and Mail, 3/14). Nucleoside analogues, a class of AIDS drugs that includes zidovudine, can damage mitochondria and disrupt the cellular energy production process, leading to fatigue, shortness of breath, weight loss and rapid heartbeat in people with HIV/AIDS who are taking the drugs. Doctors had previously measured levels of lactic acid in the blood to determine mitochondrial damage, but that test is not reliable. The new screen, which was tested on three groups of people -- those with HIV taking antiretroviral drugs who had symptoms of mitochondrial toxicity; those with HIV not taking antiretroviral drugs; and those without HIV -- found that levels of mitochondrial DNA were "significantly depleted" in HIV-positive patients who were taking drugs and who experienced symptoms such as fatigue. Once the patients stopped taking the antiretroviral drugs, their mitochondrial DNA levels "rebounded," the researchers report in the March 14 issue of the New England Journal of Medicine. Montaner and his team hope to use the test to help determine how the drugs cause mitochondrial damage so that it can be treated and prevented either by developing new drugs or by steering patients with early-stage damage away from those drugs (McKinney, Reuters Health, 3/13). "It is quite conceivable that we can use this kind of test in the long-term monitoring of the safety of our treatments," Montaner said. Dr. Mark Wainberg, director of the McGill University AIDS Center, called the test results "very significant," adding, "It illustrates the importance of having access to toxicity assays that will enable us to predict which patients are likely to handle their medications better than others" (Canadian Press/Globe and Mail, 3/14). Montaner and his team are conducting several other trials using the screen and are also examining the benefits of other treatments for mitochondrial toxicity, including vitamin shots (Reuters Health, 3/13).