A Monthly PrEP Pill Is Looking Promising, Says Study

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A new option for PrEP and the fight against HIV is on the way.

Yesterday, the annual Conference on Retroviruses and Opportunistic Infections (CROI) started. The event will run until March 10 and is being held virtually this year. At this conference, new research data focused on various types of infections will be presented. In preparation for this conference, pharma company Merck released a statement that they plan to present new data. Some of that data focuses on the development of a once-a-month PrEP pill.


In order for a new drug to enter the U.S. market, it has to pass three different trials and then get approved by the Food and Drug Administration (FDA). For Islatravir, formerly known as MK-8591, the journey to becoming a drug on the market is underway. The drug is rounding out its second stage of trials and is looking likely to go into a third one.

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According to Healio, Dr. Sharon L. Hillier, the director of reproductive infectious disease research at UPMC Magee-Women’s Hospital in Pittsburgh and a researcher of Islatravir, said the drug is “extremely potent [with] an extremely long half-life.”

“Which means that it’s a long-acting agent that can be used for prevention or treatment,” she added.


In the phase 2 trial, 250 low-risk participants were collected. They were put through a study of taking either a placebo or Islatravir for six months. Participants who took the actual drug were monitored for how quickly the medicine took effect and how long it stayed potent.

So far, the study has found that the drug has resulted in “rapid, sustained, and adequate distribution” throughout the body and levels “above the prespecified PK threshold for HIV-1.”

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Even better, the high and long potency gives the hope that people taking the drug in the future may have more leeway with consumption. Dr. Hillier notes that being late with a dose may not be as risky due to the protection Islatravir’s long-lasting effects offer.


Because of how well the Phase 2 trial went, Dr. Hillier says a Phase 3 trial is currently being set up for later this year. The trial will be conducted first on cisgender women in the US and Africa before then transitioning to gay men and trans women globally.

This is exciting news, but it’s still unconfirmed information. We have to wait to see how the drug does in its Phase 3 trials and in its review by the FDA. Only then can we celebrate a new way of taking PrEP.

Source: Merck, Healio,

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