On-Demand Preexposure Prophylaxis in Men at High Risk for Human Immunodeficiency Virus-1 (HIV-1) Infection

Conner Mansfield, Mercer University College of Pharmacy

The United States Public Health Service Preexposure Prophylaxis for the Prevention of HIV Infection in the United States Guidelines–2014 recommend that daily tenofovir (TDF)-emtricitabine (FTC) (Truvada®) be considered as an option for HIV preexposure prophylaxis for patients at high risk for HIV infection, including men who have sex with men. The 2014 guidelines specifically recommend against any dosing interval other than daily dosing. [1]

On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection [2]
Design Randomized, double-blind, placebo-controlled study; N= 414
Objective To assess the efficacy and safety of sexual activity-dependent preexposure prophylaxis with TDF-FTC among high-risk men who have sex with men
Study Groups Placebo

TDF-FTC: For isolated sexual encounters, patients took TDF-FTC 600 mg/400 mg by mouth once 2-24 hours before sex, followed by TDF-FTC 300 mg/200 mg by mouth every 24 hours for two doses starting 24 hours after the first dose. For consecutive sexual encounters, patients took the initial TDF-FTC dose, TDF-FTC 300 mg/200 mg by mouth once daily, and then received the final two doses. If patients took TDF-FTC within the previous week, the initial dose was halved, and patients took TDF-FTC 300 mg/200 mg by mouth once two-24 hours before sex.

Methods The study enrolled HIV-negative, adult males or transgender females at high risk for HIV infection. Patients received placebo or TDF-FTC above for preexposure prophylaxis and were scheduled for an in-person clinical visit four to eight weeks after enrollment and every eight weeks thereafter.
Duration Randomization occurred from January 2012 to October 2014
Primary Outcome Measure Diagnosis of HIV-1 infection
Baseline Characteristics TDF-FTC; n= 199 Placebo; n= 201
Median age—years 35 34
White race (%) 188 (94) 178 (89)
Single (%) 144 (72) 149 (74)
> Five alcoholic drinks per day in the previous month (%) 49 (25) 42 (21)
Use of recreational drugs (%) 85 (43) 92 (46)
Median number of partners in the previous two months 8 8
Sexually transmitted infection diagnosed at screening (%) 49 (25) 62 (31)
Results TDF-FTC Placebo Relative risk reduction p-value
HIV-1 seroconversion (%) 2 (1) 14 (7) 86% 0.002
Adverse Events Common Adverse Events: n= 166 (83%)
Serious Adverse Events: n= 20 (10%)
Percentage that Discontinued due to Adverse Events: n= 1 (1%)
Study Author Conclusions The study showed a reduced incidence of HIV-1 infection with sexual activity-dependent preexposure prophylaxis with TDF-FTC among high-risk men who have sex with men and who engage in unprotected anal sex.

The success of this study suggests that intermittent TDF-FTC is an effective HIV preexposure prophylaxis regimen. An intermittent regimen should decrease drug exposure, decrease costs, and could possibly increase adherence compared to currently recommended regimens.

References

  1. US Public Health Service. Preexposure prophylaxis for the prevention of HIV infection in the United States—2014: a clinical practice guideline. Available at: http://www.cdc.gov.proxy-s.mercer.edu/hiv/pdf/guidelines/PrEPguidelines2014.pdf
  2. Molina JM, Capitant C, Spire B, et al. On-Demand Preexposure Prophylaxis in Men at High Risk for HIV-1 Infection. N Engl J Med. 2015;373(23):2237-2246.
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