Clinical, Featured:

HIV Pre-Exposure Prophylaxis

By: Elissa Tam PharmD Candidate c/o 2015

HIV/AIDS continues to be a persistent problem in the United States and in various countries around the world. In 2010 alone, there were around 47,500 new HIV infections in the United States with about 1.1 million Americans living with HIV at the end of 2010.1 When left untreated, or when the patient’s immune system is severely compromised, HIV can lead to AIDS and the patient dies from infections that healthy people would normally be safe from. About 15,500 people with AIDS died in the US in 2010.1 People with HIV are highly encouraged to take cocktails of antiretroviral medications to prevent the progression of HIV to AIDS. In order to prevent the transmission of HIV, people are encouraged to exercise consistent condom use, practice sexual abstinence, limit the number of sexual partners and never share needles.2 There is also a new method of preventing HIV that has been explored for some time: the use of HIV antiretroviral therapy in HIV-uninfected patients at high risk for HIV infection.

The idea of using antiretroviral therapy in HIV-uninfected patients has been discussed through the years but just recently, in May 2014, the Centers for Disease Control and Prevention (CDC) released its guidelines for the use of daily pre-exposure prophylaxis (PrEP). When taken daily as directed, pre-exposure prophylaxis (PrEP) can reduce the risk for HIV infection by more than 90%. “While a vaccine or cure may one day end the HIV epidemic, PrEP is a powerful tool that has the potential to alter the course of the US HIV epidemic today,” Jonathan Mermin, MD, MPH, director of CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, said in a statement.3 PrEP medication is not a vaccine; it is a pill called Truvada® (tenofovir and emtricitabine) that has been shown to help block HIV infection.3

The CDC recommends that PrEP therapy be considered for the following patients: 1) anyone who is in an ongoing sexual relationship with an HIV-infected partner, 2) a gay or bisexual man who has had sex without a condom or has been diagnosed with a sexually transmitted infection within the past 6 months and is not in a mutually monogamous relationship with a partner who recently tested HIV-negative, 3) a heterosexual man or woman who does not always use condoms when having sex with partners known to be at risk for HIV (eg, injecting drug users or bisexual male partners of unknown HIV status), and is not in a mutually monogamous relationship with a partner who recently tested HIV-negative, and 4) anyone who has, within the past 6 months, injected illicit drugs and shared equipment or been in a treatment program for injection drug use.3 In the United States, it is estimated that as many as 275,000 uninfected gay and bisexual men and 140,000 uninfected partners in HIV-discordant heterosexual couples could benefit from PrEP.3

Despite the promise of preventing and curbing the spread of HIV, there are criticisms of PrEP that include issues of adherence, behavioral repercussions, cost, and safety/effectiveness. The adoption of the drug also has been slow. Many clinicians are hesitant in providing a medication to healthy people. Moreover, the perception of buying unnecessary medications for a disease that they do not currently have is a reason why potential patients are reluctant to ask for PrEP.4

The level of effectiveness of the medication for prevention depends on how adherent the patient is. A double blind, placebo-controlled phase III clinical trial called iPrEx was conducted in 11 study sites with a total of 2,499 HIV uninfected participants to determinate whether Truvada® could safely and effectively prevent HIV acquisition through sex in men who have sex with men.5 According to the iPrEx Study, among gay and bisexual men, those who were given PrEP were 44% less likely overall to get HIV than those who were given a placebo. Among the men with detectable levels of medicine in their blood (meaning they had taken the pill consistently), PrEP reduced the risk of infection by as much as 92%.6 This data reinforces the fact that the therapy should not be taken for a few weeks or months and then stopped, and then started again, but rather it should be taken continuously. As such, some people find it difficult to adhere to such a daily regimen.

Moreover, effects of PrEP may result in behavioral changes such as decreased condom use.1 Many public-health officials believe that people will see it as a substitute for condoms.4 However, though PrEP offers the best protection when taken daily, it is not 100% effective. Condoms serve as additive protection against HIV, as well as against infections such as gonorrhea, chlamydia and hepatitis that is not offered with PrEP. 1 Truvada®, in itself, is very expensive. It is listed at more than $1500/month.7 While most insurers cover the treatment, there are some people who do not have insurance or the medication is out of reach for them.

PrEP is relatively safe, with early, mild side effects from clinical studies ranging from upset stomach to loss of appetite. Effects of Truvada® on kidney function appear to be temporary.8 No serious side effects were observed. While bone-density loss occasionally occurs in Truvada® takers who are already infected with the virus, no significant bone issues have emerged in the PrEP studies. And though about one in ten PrEP takers suffer from nausea at the onset of treatment, it usually dissipates after a couple of weeks.Perhaps more importantly, drug resistance has not been observed in people who were HIV-negative when they began treatment. “We’re not seeing people getting infected who are actually taking the drug,” said Dr. Robert Grant, a professor at the University of California San Francisco and NIH study’s lead scientist. “There are people who take the drug home with them and choose not to take it; they get infected, but you’re not going to get drug resistance from something that stays in a drawer.” 4

Regardless of the criticism and the slow use of using PrEP, it is still considered a powerful HIV prevention tool. If combined with condoms and other preventive methods, it is hoped that it will be successful in preventing HIV and slowing the progression of the pandemic.


  1. HIV/AIDS. Centers for Disease Control and Prevention. Published June 18, 2014. Accessed July 20, 2014.
  2. “HIV and Its Transmission”. Centers for Disease Control and Prevention. 2003. Archived from the original on February 4, 2005. Accessed July 20, 2014.
  3. Brooks M. CDC Updates HIV Preexposure Prophylaxis Guidelines. Medscape Medical News. Published May 14, 2014. Accessed July 20, 2014.
  4. Glazek C. Why is No One on the First Treament to Prevent HIV? New Yorker. Published October 1, 2013. Accessed July 20, 2014.
  5. National Institute of Allergy and Infectious Diseases (NIAID); Bill and Melinda Gates Foundation. Emtricitabine/Tenofovir disoproxil fumarate for HIV prevention in men. In: [Internet]. Bethesda (MD): National Library of Medicine (US). 2000- [cited 2014 Oct 10]. Available from: Identifier: NCT00458393.
  6. Grant RM, Lama JR, et. al. Preexposure Chemoprophylaxis for HIV Prevention in Men Who Have Sex with Men. The New England Journal of Medicine. Dec 2010; 363(37):2587-99
  7. Truvada. Lexi-Comp. Accessed July 20, 2014.
  8. Celum CL. HIV preexposure prophylaxis: new data and potential use. Top Antivir Med. 2011;19(5):181-5.

[pubmed_related keyword1=”HIV” keyword2=”prophylaxis” keyword3=”infection”]


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