Would you use an HIV-preventing enema or rectal PrEP?

Would you use an HIV-preventing enema or rectal PrEP?

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A man weighs up a decision, deep in thought
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Researchers continue to look at ways to help protect people from acquiring HIV. Some recent studies have looked at methods to quickly get HIV-preventing drugs into your body when they’re most needed.

Although a daily tablet is the most common way of taking PrEP, not everyone wants to take a pill every day of their life. Also, in some parts of the world, including parts of the US, access to PrEP is not straightforward.

A recent clinical trial tested whether people would be happy to insert rectal microbicides—an experimental HIV-prevention strategy—inside their butt before anal sex.

Rectal microbicides are not PrEP drugs, but a different form of HIV-prevention medicine that works on anal and rectal tissue before sex. Until now, it’s very difficult to apply microbicidal gel far enough inside the rectum to provide good protection. That’s why researchers are exploring other routes of delivery.

They gave their test subjects three methods of anal insertion: Enemas, suppositories, and rectal inserts. From the images they included, there’s not a huge difference between a suppository and an insert besides size.

In each case, placebos were used. The study wanted to determine if people were happy with insertion methods. It was not looking at the effectiveness of the drugs.

Popular were PrEP is not easily available

The most popular form of insertion proved to be enemas and rectal inserts. Seventy percent of people tested used enemas and inserts regularly, and more than 75% rated them both highly. This edged ahead of suppositories.

The trial took place in Peru, South Africa, Thailand, Malawi, and the United States. Enemas proved widely popular, but popularity dipped slightly in some US cities, including San Francisco. The researchers speculate that this could be because PrEP is widely available in such locations, so participants might be less enthused about other HIV prevention methods.

The participants — mainly cisgender gay men aged 18-35 — were evaluated after four weeks. They reported an average number of five receptive anal sex encounters, with three different men, during that period.

The number of people who said they used one of the methods on all occasions was: 83% for the enema, 75% for the rectal insert, and 74% for the suppository.

The authors say, “Our trial addresses the limited data available regarding the safety and acceptability of and adherence to enemas, inserts, and suppositories as potential modalities through which to deliver a rectal microbicide. Findings from this trial demonstrate high safety profiles, alongside high levels of acceptability and adherence, among all three.”

Further research is now needed to prove that rectal microbicides work effectively when delivered by these methods.

Rectal PrEP

Besides a daily PrEP pill, a long-acting injectable form of PrEP is also available in the US.

PrEP is also known to be highly effective if taken before and after sex (usually, two pills taken 2-24 hours before sex and then another pill 24 hours after the first dose and then again after another 24 hours). This 2-1-1 method is known as “on-demand” or ” event-driven” PrEP. The FDA has not approved this method in the US but it’s known that some guys use PrEP this way.

Researchers continue to look for other ways to administer the drug.

A group of researchers at the Contraceptive Research and Development (CONRAD) program have explored whether a quickly-dissolving PrEP pill that is inserted into the rectum or vagina also works.

Dr. Sharon A. Riddler, a professor of infectious diseases at the University of Pittsburgh School of Medicine, shared the results of a study earlier this year at the Conference on Retroviruses and Opportunistic Infection in Seattle in February.

Anal inserts offer protection in nonhuman primates. This led Riddler and her team to studying 23 people, mainly men.

The participants took a PrEP insert. Afterward, blood, rectal fluid, and rectal tissue were collected. This was to check if the drug had entered their tissue and bloodstream. Researchers repeated the process seven weeks later, but with two inserts.

“Safe, discreet, on-demand”

The test showed positive drug uptake. However, two inserts worked better than one. The higher dosage increased the risk of mild side effects (mild anal inflammation or rash) in one participants. However, this was not extreme enough to dissuade the researchers. They believe rectal PrEP is worth investigating further.

“Although the currently available products for prevention (oral, injectable, ring) have all been proven to be effective, there remain many barriers to these being used by people with the greatest need for prevention,” said Riddler.

“Additionally, even people who can access PrEP often do not because of cost, side effects, inconvenience, etc., so the continued development of a safe, discreet, on-demand, flexible option would be a great outcome of this small Phase 1 clinical trial.”

In short, if you only want to take HIV protection when you know you’re bottoming, more specific methods to do so could be on the horizon.


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