A new study from the University of North Carolina at Chapel Hill reveals that the only FDA approved medicine to reduce HIV infection “Truvada” accumulates differently on different body tissues. The researchers have also mentioned that men only need two doses per week while women need daily doses of PrEP antiviral medication.

According to the lead author of the study Angela Kashuba, Pharma.D., this research will help improvising the strategy to prevent HIV infections, which could also have major implications for clinical trial designs. She is also the John and Deborah McNeill Distinguished Professor at the UNC Eshelman School of Pharmacy. She said:

“Our data highlight the fact that one dose does not fit all. In determining how best to use drugs to protect people from HIV, we need to understand where in their body, they are at risk for being infected, along with the concentration of drug that is needed to protect that site from infection.”
Antiviral medication Truvada’s daily dosage was approved by the Food and Drug Administration (FDA) in 2012 to prevent the spread of HIV infection. This medicine has showed reducing the infection rates of HIV, and it’s the only medicine approved by FDA. This medicine was developed by Gilead Sciences, Inc (NASDAQ:GILD).

In the previous clinical researches, the only pre-exposure prophylaxis medicine Truvada (Tenofovir disoproxil/emtricitabine) was shown as a more effective drug for men in reducing HIV infection rates more than women, despite similar rates of drug adherence. With the help of mixed clinical trial results, the current study shows that different tissues present in men and women require different dosage of medicine to stop spreading of the virus.

According to the study, the rectal, vaginal and cervical tissue accumulates the PrEP drug differently. Only fewer components of the antiviral medication reaches into vaginal and cervical tissues than rectal tissue. Researchers also noted that the virus reproduce more in cervical and vaginal tissues because of the DNA material present in these types of tissues than the rectal tissue. Hence, concluded that two times of Truvada needed for effective medication.

“The more DNA material there is available for HIV to work with, the more medicine is needed to block the process,” said Mackenzie Cottrell, M.S., Pharm.D., a research assistant professor at the pharmacy school and lead author of the study. “In essence, we calculated the most effective drug-to-DNA ratio for each tissue type.”

The team from the University of North Carolina at Chapel Hill measured how much DNA material was in human cells and how much PrEP needed to prevent the virus infection in these cells, by using human cells in a test tube. The team also gave the Truvada medication to healthy female volunteers to measure the amount of drug’s components reach into rectal, vaginal and cervical tissues. They have also measured the DNA material present in these tissues of those female volunteers. By having the test tube data as well as the human data, the researchers developed a mathematical model to predict and calculate the drug ratio required for each of these tissues.

The combination therapy of two HIV drugs – namely tenofovir and emtricitabine – performed well in clinical trials compared to a placebo, working to multiply inside CD4 cells or T-cells that are important in the fight against infections.