What is the antiviral regimen for Human Immunodeficiency Virus (HIV) prophylaxis and its success rate?

From the Guidelines

The recommended antiviral regimen for HIV post-exposure prophylaxis (PEP) consists of a three-drug combination typically including tenofovir disoproxil fumarate (TDF) 300mg plus emtricitabine (FTC) 200mg once daily, along with either raltegravir 400mg twice daily or dolutegravir 50mg once daily, with a success rate of approximately 80-90% in preventing HIV infection after exposure, as supported by the 2016 recommendations of the International Antiviral Society-USA panel 1.

Key Considerations for PEP

• The regimen should be started as soon as possible after exposure, ideally within 72 hours, and continued for 28 days.
• Baseline assessments should include HIV antibody testing, sexually transmitted infection testing, pregnancy testing for women of childbearing potential, and hepatitis B and C serologies.
• PEP should be continued for 28 days, and HIV serostatus should be reassessed at 4 to 6 weeks, 3 months, and 6 months after exposure.

Pre-Exposure Prophylaxis (PrEP)

• The standard regimen is daily TDF/FTC (marketed as Truvada) or tenofovir alafenamide (TAF)/FTC (marketed as Descovy), with on-demand dosing sometimes used for men who have sex with men.
• PrEP is even more effective, reducing the risk of HIV acquisition by more than 99% when taken daily as prescribed, as noted in the 2016 recommendations 1.

Importance of Adherence and Monitoring

• Adherence to the medication schedule, timing of initiation after exposure for PEP, and consistent use for PrEP are crucial for the effectiveness of these regimens.
• Regular HIV testing, kidney function monitoring, and screening for other sexually transmitted infections are important components of care for individuals on these regimens, as emphasized in the guidelines 1.

From the FDA Drug Label

The efficacy and safety of emtricitabine were evaluated in the trials summarized in Table 10 Trial 934 was a randomized, open-label, active-controlled multicenter clinical trial comparing emtricitabine + TDF administered in combination with EFV versus AZT/3TC fixed-dose combination administered in combination with EFV in 511 antiretroviral-naïve subjects Through Week 48,84%, and 73% of subjects in the emtricitabine + TDF group and the AZT/3TC group, respectively, achieved and maintained HIV-1 RNA <400 copies/mL

The antiviral regimen for HIV prophylaxis is emtricitabine + TDF + EFV. The success rate of this regimen is:

• 84% of subjects achieved and maintained HIV-1 RNA <400 copies/mL through Week 48
• 71% of subjects achieved and maintained HIV-1 RNA <400 copies/mL through Week 144
• 80% and 70% of subjects in the emtricitabine + TDF group and the AZT/3TC group, respectively, achieved and maintained HIV-1 RNA <50 copies/mL through Week 48
• 64% and 56% of subjects in the emtricitabine + TDF group and the AZT/3TC group, respectively, achieved and maintained HIV-1 RNA <50 copies/mL through Week 144 2

From the Research

Antiviral Regimen for HIV Prophylaxis

The antiviral regimen for Human Immunodeficiency Virus (HIV) prophylaxis includes:

• Bictegravir/emtricitabine/tenofovir alafenamide or dolutegravir plus (tenofovir alafenamide or tenofovir disoproxil fumarate) plus (emtricitabine or lamivudine) as the preferred regimens for most adults and adolescents 3
• The regimen can be tailored to the clinical circumstances
• A 28-day course of nonoccupational postexposure prophylaxis (nPEP) is recommended after a nonoccupational exposure to HIV 3

Success Rate of HIV Prophylaxis

The success rate of HIV prophylaxis is as follows:

• Pre-exposure prophylaxis (PrEP) with oral tenofovir disoproxil fumarate/emtricitabine or tenofovir disoproxil fumarate monotherapy was associated with a decreased risk of HIV infection vs placebo or no PrEP (relative risk [RR], 0.46 [95% CI, 0.33-0.66]) 4
• Greater adherence to PrEP was associated with greater efficacy (RR with adherence ≥70%, 0.27 [95% CI, 0.19-0.39]) 4
• The effectiveness of PrEP decreased with suboptimal adherence 4
• Nonoccupational postexposure prophylaxis (nPEP) has been shown to be effective in preventing HIV infection if initiated promptly after exposure 3, 5, 6