CHAPEL HILL, N.C. – Compared to men, women need higher levels of the antiviral medication Truvada, the blue pill that is approved for preventing HIV infection.

A new study conducted by researchers from the University of Carolina and published in Journal of Infectious Diseases revealed that women require daily doses, whereas men only need two doses a week.

Truvada is the only approved drug for preventing HIV, but a gay man in Toronto, Canada, had taken the pill for 24 months before being recently diagnosed with the virus. This marked the first report of the drug’s failure to work. Photo: THOR SWIFT / New York Times

“In determining how best to use drugs to protect people from HIV, we need to understand where in their body they are at risk of being infected, along with the concentration of drug that is needed to protect that site from infection”, said lead author and professor Angela Kashuba.

When comparing the effectiveness of Truvada in men and women, researchers found that twice as much of this drug is required to prevent infection in vaginal and cervical tissue than in rectal tissue because fewer components can make it into those two types of tissue. Besides, women need a higher dose of Truvada given that the virus uses more DNA material for reproducing in vaginal and cervical tissue.

The U.S. Food and Drug Administration advises men to take the drug every day, but the authors of this study say males may not need to take it more than twice a week. However, the researchers said men should not stop taking the blue pill daily without a doctor’s approval.

Researchers used human cells in a test tube to measure the amount of DNA material in the cells and examine how much of Truvada was needed to prevent HIV infection in them. They then gave the drug to 47 healthy women and tested the medication levels and DNA material present in each of them after gathering samples of vaginal, cervical and rectal tissues.

Truvada, produced by Gilead, was approved by the FDA as a “pre-exposure prophylaxis” (PrEP) of HIV. The combination of two HIV drugs called tenofovir and emtricitabine was successful in clinical trials compared to a placebo, working to multiply inside T-cells or CD4 cells that play an important role in the fight against infections.

The blue pill is not always 100% effective

Dr. David Knox, an HIV expert, suggested that Truvada’s failure could have been caused by a rare transmission of an HIV 1 strain that resists to both emtricitabine and tenofovir. Other specialists say that the medication could have failed because of an inconsistent or sporadic intake, but the man infected said he religiously took the pill for two years.

Source: UPI