Primary Care Blog
On Tuesday, July 17, 2012, the US Food and Drug Administration issued it’s first-ever approval of a medication to be taken to prevent someone who is HIV-negative from becoming infected if they know that are about to engage in sexual behaviors that are “high risk” for contracting the virus. The pill in question is a once a day tablet that contains two medications, emtricitabine and tenofovir, which is marketed under the brand name Truvada by Gilead Sciences, Inc. The combination of emtricitabine and tenofovir is one that I prescribe frequently, as they are safe, effective, and easy to take, making them a very common component of treatment regimens for HIV infected patients. In fact, the official treatment guidelines from the NIH recommend that these two medications be a part of any of the best starting regimens for people with HIV infection who have never been treated before, all else being equal.
There will undoubtedly be a lengthy and complex public debate stirred by the approval of the emtricitabine/tenofovir combination pill as a way to prevent HIV infections in HIV negative but high-risk patients. Many public health officials are lauding this as a new tool that will help us significantly reduce the number of new people who acquire HIV infection in the US, to a degree that public education, testing, and condom distribution programs have not. Critics (ridiculously, in my humble opinion) contend that this is a pill that will enable risky sexual behaviors and promote promiscuity. As always, the truth about the use of this medicine, human behavior, and several legitimate concerns lie between those two extremes.
An important thing to understand as to why we’ve been unsuccessful in curbing the number of people who get HIV1 is this: human behavior. It turns out that people like to have sex! And in the heat of the moment, as it were, sometimes very bad decisions are made in terms of safe sex. This includes the oldest, cheapest, most effective (when used correctly) way to prevent sexually transmitted infections, namely condoms. Certainly, there are many barriers2 to individuals considering condom use. Some avoid condoms because they perceive them as having negative effects on sexual pleasure, either through decreased sensation or the odor/taste of latex. Others aren’t simply informed of or comfortable with the idea of condoms to consider their use. Still others are of the belief that condom use is immoral or a sin, and so refuse to use them on that basis. All of this is to say nothing of the complex emotional and sexual politics that underlie many relationships, which can have roots in fear, uncertainty, desire to please, machismo, cultural expectations, and abuse, and can lead to condoms not being used. This is why a key strategy in HIV prevention always will be education about condom use, and making access to them easy.
Despite the efforts at condom education and an uptake in their use, why hasn’t this been successful in dramatically diminishing the spread of HIV? The answer again lies with human behavior. Condoms, when used correctly, can reduce the chances of getting a sexually transmitted infection by 98%… but that hinges on the “when used correctly” part. It turns out that a large proportion of humans use condoms incorrectly on a disturbingly frequent basis, doing everything from putting them on too late or taking them off early, to wearing them inside out or inadvertently damaging them in some way. The article “Condom Use Errors And Problems: A Global View” from the February 17, 2012, edition of the journal Sexual Health is a review article of numerous studies that document in detail the percentage of people who misuse condoms, sometimes in quite crazy ways. It’s an open access article, so I’ll pause while you go check it out, especially the tables cataloging types and numbers of condom use errors.
Back and properly horrified? Good. So for all of these reasons, human behavior has made the condom, which is very effective on an individual basis at preventing the transmission of HIV when used properly and consistently, into a thing that in our population as a whole, fails as an intervention to stop the spread of HIV.
This brings us back to the emtricitabine/tenofovir combination pill. The FDA has approved it for usenot in everyone who is sexually active, but only for those who are confirmed to be HIV-negative by testing and who are engaged in sexual behaviors that are considered “high risk” for contracting HIV infection: not using condoms, having sex with multiple partners, engaging in sex with people of unknown HIV status or who are HIV-positive, or either giving or receiving sex for commodities. The FDA is also mandating 1. physician and patient education about the medicine, 2. that it must be used alongside counseling on safe sex practices, including condom use and access, 3. that patients on the medicine be tested for HIV every three months, and 4. that Gilead take blood samples from any patient who does become HIV-positive while on the medicine to analyze for the possibility that their HIV virus has become resistant to it. This is a very reasonable set of requirements, and has me both optimistic about emtricitabine/tenofovir’s upcoming use in the role, and somewhat concerned as well.
I am optimistic for several reasons. All of the barriers to condom use noted above do not exist with this pill: there’s no operator error involved, it’s not a contraceptive and so doesn’t fall into that religious realm, and the sexual partner of the patient doesn’t even need to know that person is taking the medicine. Also, there are several groups of people in particular who I see benefiting from using this to prevent HIV, including people who are in a monogamous sexual relationship with an HIV-positive partner, and those who are unable or unwilling to practice safe sex in a relationship due to the emotional or sexual politics involved. Additionally, adding this into the mix in a widespread way stands a good chance of finally causing the incidence rates of new HIV infections to drop significantly from year to year, and bring us ever closer to beating this awful infection. Finally, this will hopefully spur better, more honest dialogue among people and between patients and their primary care doctors about sexual issues, which in some elements of US society is sorely needed.
All that noted, there are some concerns that I have about introducing emtricitabine/tenofovir in this new way. The people who will be prescribing it will be primary care doctors, not infectious diseases specialists, who as a group have little experience with this medicine or its side effects, especially when taken over the long term, which could lead to patient illness from the medicine itself. Despite the strict FDA approval criteria, once this new indication gets “out in the wild”, the barriers to it being incorrectly prescribed are relatively low. There will be a tendency for some people who engage in high risk behavior to see this as a reason not to attempt to modify their behavior, which leads to a greater risk of other infections besides HIV. The studies done on this pill to prevent HIV infections showed a 50-75% reduction in people becoming HIV-positive compared to placebo, which is very notable but nowhere near 100%.3 If someone takes the medication inconsistently, or an HIV-positive person gives an HIV-negative person a pill from their supply and therefore missed out on their own dose at some point, the chances of the spread of HIV that is resistant to this medication (that is a cornerstone of HIV treatment) in the population increase and could make it much harder to treat new HIV infections in the future. Also, this pill is expensive, and many people who are in the high-risk category also are living in poverty and have no health insurance; while there are programs to get HIV-positive patients access to HIV treatment despite these circumstances, no such thing currently exists yet for the HIV-negative target group.
The next few years will tell how well emtricitabine/tenofovir succeeds in its new role of preventing HIV infection, and whether it can effectively counter the extremely hard-to-modify juggernaut of human behavior. I can do nothing other than be optimistic.
- While the number of people diagnosed with HIV annually has plateaued as of several years ago instead of increased, neither has it decreased significantly; the FDA press release notes that approximately 50,000 new adult and adolescent diagnoses occur annually. [↩]
- Get it?! See what I did there? “Barriers”. Uh, nevermind. [↩]
- It is also important to note that those studies gave everyone involved intensive, repeated safe sex counseling including condom education and access. [↩]
This was originally posted on The Secret Lair
