Hair analysis may help determine drug levels, adherence and virological response

Doctors can get a handle on how well an HIV-infected person is responding to antiretroviral drugs – as well as whether or not they are actually taking their medicine – by testing a sample of the patient’s hair, researchers have reported.

Current methods used to monitor how well the drugs are working are “inefficient and inaccurate,” the researchers note in the October issue of the Annals of Internal Medicine in their report “Relationship Between Levels of Indinavir in Hair and Virologic Response to Highly Active Antiretroviral Therapy”.

Dr Louis Bernard of Geneva University Hospital in Switzerland and colleagues looked at 89 HIV-infected patients who were taking HAART that included indinavir. Levels of the drug were measured in the patients’ hair and blood. A low level of the drug could be a sign that patients were not taking their medicine consistently or that the drug was not being absorbed completely.

The authors found that 65 patients had high levels of indinavir in their hair and those patients tended also to have low levels of virus in their blood compared with the 24 patients deemed non-responders. Those with the highest concentration of the drug in their hair were also less likely to have drug-resistant strains of HIV than non-responders. The new test represents an improvement over testing blood samples because blood levels only reflect the medication doses most recently taken by the patient.

“Given the importance of long-term adherence to antiretroviral therapies for optimal outcome, hair analysis represents a significant, convenient and affordable advance in assessing exposure to antiretroviral therapies over extended periods,” write Drs Monica Gandhi and Ruth M Greenblatt of the University of California-San Francisco, authors of an editorial accompanying the study.

Bernard L, Vuagnat A, Peytavin Get al. Relationship between levels of indinavir in hair and virologic response to highly active antiretroviral therapy. Ann Intern Med 2002 Oct 15;137(8):656-9