Women Have To Take A Lot More Of The HIV Preventing Drug Truvada Than Men For It To Be Effective

A recent study has found that Truvada, the only drug approved for the prevention of HIV infection, reacts differently in the male and female body and, as such, actually has different dosing requirements for men and women. The pharmacy researchers from the University of North Carolina at Chapel Hill discovered that while women need to take daily doses of Truvada to prevent HIV infection, men only need to take two doses per week.

Approved by the Food and Drug Administration in 2012, Pre-Exposure Prophylaxis (PrEP), otherwise known as Truvada, was marketed as being safe for daily use by people with high-risk of infection, and in all areas where it has been made available, it has proven to have reduced the cases of new infections by a significant amount.

The newest study, published in the Journal of Infectious Diseases, is being seen as a major paradigm shift in the way that prevention strategies for HIV are tackled. The senior author of the study, Angela Kashuba, PharmD, who is also the John and Deborah McNeill Distinguished Professor at the UNC Eshelman School of Pharmacy, has also stated that the new finding will also have significant implications for any and all future clinical trial designs.

“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.”

The way the drug accumulates in different body types and tissues is being said to account for the difference in the doses of Truvada required by women and men. Previous clinical studies have shown that Truvada proved that despite similar habits of taking the pill, the drug was more effective at reducing the infection rates in men than it was in women. Kashuba and her team have been the first researchers to actively explain the reason behind such mixed results in the clinical trial.

According to Infection Control Today, the Kashuba team revealed that tissue from the cervix, vagina, and rectum all respond differently to Truvada. Preventing HIV infection of the vaginal and cervical tissue requires twice the amount of the drug that is necessary to prevent infection in the rectal tissue, and this is because fewer Truvada components make it into female tissue. More of the drug is also required by women to prevent infection due to the fact that the vaginal and cervical tissues have more of the DNA material, which the HIV virus needs to reproduce.

In order to determine how much Truvada was needed to prevent HIV infection in the different cells, the UNC-Chapel Hill team measured how much DNA material was present in the tissues by studying human cells in a test tube. Healthy female volunteers were then given Truvada, and the research teams measured how much of the drug was distributed to tissue in the vagina, cervix, and rectum, and how much DNA material was present as well. Both the data from the women and the test tube data was then used to create a mathematical model, which predicts the drug-to-DNA ratios in vaginal, cervical, and rectal tissues and, in turn, gives accurate calculations of exactly how much of the PrEP drug is needed to prevent HIV infections in the tissues of humans.

UPI stated that Kashuba is urging people to not stop taking Truvada daily despite the new information available. Kashuba added that understanding the exact amount of the drug required to combat HIV infection rates in different tissue cells should help improve prevention methods.

“We would like to remind people who are taking pre-exposure prophylaxis that Truvada should be taken every day to reduce the risk of acquiring HIV infection. Patients should not change their medication regimen without first consulting their physicians.”

A different study in January concluded that taking daily doses of PrEP is as safe as a daily aspirin to aid in preventing heart attacks.

[Photo by Justin Sullivan/Getty Images]

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