New blood spot test to diagnose HIV

New blood spot test used internationally in fight against HIV as new Technique developed which measures patient adherence to anti retroviral drugs which the only method by which HIV is controlled.

Researchers at the Skaggs School of Pharmacy and Pharmaceutical Sciences at CU Anschutz have developed a technique that estimates an HIV-negative patient's adherence to drugs prescribed to prevent HIV transmission during sex.

The test measures traces of antiretroviral drugs in a spot of dried blood to determine how much pre-exposure prophylactic, or PrEP, medicine a patient has used. Truvada, the only FDA-approved antiretroviral PrEP drug for HIV prevention, is proven more than 90 percent effective in stopping HIV transmission during sex -- in those who use it consistently. The assay technique provides an objective way to tell if patients are using PrEP consistently.

"There's a need to objectively measure PrEP adherence because traditional ways have not been very effective," said Pete Anderson, Pharm.D. and professor of pharmaceutical sciences at the CU Skaggs School of Pharmacy. "This assay takes advantage of the long half-life of PrEP medication in red blood cells. This means the drug builds up in these cells only if the patient takes it consistently."

The method is to spot a sample of a patient's blood on an absorbent paper-like card and send it to a lab which isolates and measures concentrations of PrEP drugs found in dried red blood cells. These drugs' presence are measured to estimate how many doses a patient has taken over the last month or two. Clinicians then have an objective measurement that shows if a patient is using PrEP effectively. Studies show that people using the PreP method are most successful when medication is used consistently.