Prevent HIV with just four pills?

Can you prevent HIV with only four pills?

PrEP (pre-exposure prophylaxis) is the term used for methods to prevent disease transmission before contact with the disease actually occurs.

In HIV, PrEP centers around taking an oral medication daily, in conjunction with condom use, to prevent infection by the virus that causes AIDS.

In studies, PrEP seems to be quite effective in decreasing HIV transmission in men who have sex with men (MSMs).

A new drug trial is now suggesting that PrEP might be just as effective taken only right before, and in the immediate two days following, sexual activity.

Truvada (photo courtesy of Jeffrey Beall)

Truvada (photo courtesy of Jeffrey Beall)

The drug trial is called IPERGAY, and it uses the drug Truvada® as PrEP (Preexposure Prophylaxis) against HIV. The main difference between IPERGAY and other PrEP studies is that in the other studies Truvada® (a combination of emtriciabine and tenofovir) is given as a once-daily dose. It needs to be taken every day, and it is strongly suggested that condoms be uses in conjunction with the drug.

In IPERGAY, the Truvada® is given only around the time that sex takes place. It’s not given as a regular daily dose that is taken independent of whether the patient has sex. So the Truvada® in IPERGAY is more of an “as needed” pill.

Their dosing schedule is:

Two pills taken anywhere from 2 to 24 hours before anal penetrative sex. Then one pill taken 24 hours after that. And a final pill is taken 24 hours later, and that’s the complete sequence.

One problem with the standard PrEP routine is that the medication is expensive and would be more expensive if it needed to be taken daily versus just taking it sporadically. Of course, that would be dependent upon how frequently the patient engaged in sex.

AIDSMap is reporting that IPERGAY has been so successful that, while the trial will continue, the control patients will be invited to start on Truvada® just as the experimental group is doing. While AIDSMap hasn’t linked to the data (I’ve emailed IPERGAY to try to get the information directly from them), it is obviously good enough to close the control arm of the research (the controls are those who are not taking the test drug and are receiving a placebo instead.)

In other words, the sporadic use of Truvada® as described is so effective at preventing HIV infections that it would be unethical to allow the control patients to continue to go without it. When I get hard data on the study, I’ll post that.

These results could be a very good thing, or not. I have a few concerns with the IPERGAY dosing philosophy.

First, Truvada® as PrEP has been available in the US for some time, but very few men are taking it.

A survey done about a year ago, asked men who have sex with men (MSMs) why they weren’t using PrEP. A significant number said that they didn’t want to take a pill a day — that it was inconvenient. Remember, getting someone to take a single pill once a day is fairly easy and convenient for most people. Taking pills on an erratic schedule, however, is difficult for a lot of people. As a consequence, often doses get missed. Sometimes people just stop the medication entirely. Thus,Truvada® taken every day for life is easy. Truvada taken only right before you have sex, and two days following, is more sporadic, and thus potentially more difficult for patients to remember.

Something that might work better would be an implantable form of Truvada®. Basically, a small reservoir of the medication, inserted in the skin every three months by the doctor. That would coincide with the quarterly HIV testing, other testing and follow up that is recommended when on PrEP. Also, it would make it impossible for the patient to miss doses. The dose is automatically released daily.

Next, with the use of on demand when sex occurs only type of dosing we might encounter the Viagra® problem.

Many commercial health insurances will only permit patients to receive a limited number of Viagra (often only 3) per month. Above that, the patient has to pay for additional pills out of pocket. I’m almost certain, with the high cost of PrEP, insurance companies would ration the number of pills that they’d pay for per month. If that’s the case, then many patients would not take them as directed and would take one or two around the time of intercourse instead of following the prescribed dosing. Either of the above could lead to failure of the medication to protect against acquisition of HIV.

Then we have the Hobby Lobby decision form SCOTUS.

One can imagine right-wing religious corporations fighting against paying for any form of PrEP, simply because the(ir) Bible is against same-sex sexual relations. So far, I haven’t seen any instances of that happening with PrEP (or antiretrovirals), but it seems like it could be a real possibility to me.

So while the IPERGAY trial is good news to an extent (that people who diligently take their PrEP as directed are protected against HIV), there may well be some downsides to look out for.


Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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