What is the purpose of Truvada (emtricitabine and tenofovir disoproxil fumarate) in the treatment of HIV-1 infection?

What Truvada Does

Truvada (emtricitabine/tenofovir disoproxil fumarate) is a fixed-dose combination antiretroviral medication used for two primary purposes: treating HIV-1 infection when combined with other antiretroviral agents, and preventing HIV acquisition as pre-exposure prophylaxis (PrEP) in high-risk individuals. 1

Treatment of HIV-1 Infection

For HIV Treatment:

• Truvada serves as the nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) backbone in combination antiretroviral therapy (ART) regimens 2
• It is used in combination with other antiretroviral agents (such as integrase inhibitors, protease inhibitors, or non-nucleoside reverse transcriptase inhibitors) to suppress HIV viral replication 1, 3
• The standard dose is one 300mg tenofovir DF/200mg emtricitabine tablet taken once daily, with or without food 1
• It is approved for adults and children 2 years of age and older weighing at least 10 kg 1

Mechanism in HIV Treatment:

• Emtricitabine and tenofovir both inhibit HIV reverse transcriptase, blocking viral replication at the cellular level 4, 5
• When used as part of combination therapy, Truvada helps achieve and maintain viral suppression (HIV RNA <50 copies/mL) 2, 3

Pre-Exposure Prophylaxis (PrEP) for HIV Prevention

For HIV Prevention:

• Truvada is highly effective as daily PrEP for preventing HIV acquisition in high-risk populations 2, 6
• Daily TDF/emtricitabine reduces HIV infection risk by approximately 86% when taken as prescribed 2
• It is recommended for populations with HIV incidence above 2% per year 2

PrEP Dosing Strategies:

• Daily dosing: One tablet daily is the standard regimen for all at-risk populations, including men who have sex with men (MSM), heterosexual individuals, and people who inject drugs 2, 7
• On-demand "2-1-1" dosing: For MSM with infrequent sexual exposures only—2 tablets 2-24 hours before sex, 1 tablet 24 hours after the first dose, and 1 tablet 48 hours after the first dose 2, 7
• On-demand dosing is NOT appropriate for vaginal exposures or injection drug use 7

Time to Protection:

• For receptive anal sex: 2-3 days of daily dosing provides protection 7
• For receptive vaginal sex: 7 days of daily dosing is required for full protection 2, 7

Treatment of Chronic Hepatitis B

For Hepatitis B:

• Truvada (specifically the tenofovir component) is indicated for treating chronic hepatitis B virus (HBV) infection in adults and children 12 years and older 1
• Critical warning: Severe acute exacerbations of HBV can occur if Truvada is discontinued in HBV-infected patients 1
• Hepatic function must be monitored closely for several months after discontinuation, and resumption of anti-HBV therapy may be warranted 1

Important Clinical Considerations

Before Starting Truvada:

• Test for both HIV and HBV infection 1
• Assess baseline renal function (serum creatinine, estimated creatinine clearance) 1
• For PrEP: Perform combined HIV antigen-antibody testing within 7 days before initiation 2, 7
• Screen for sexually transmitted infections 8

Monitoring During Use:

• For HIV treatment: HIV RNA levels within 6 weeks of starting, then every 3 months until suppressed for 1 year, then every 6 months 2
• For PrEP: HIV testing at 1 month and quarterly thereafter, creatinine clearance at first quarterly visit and annually, STI screening quarterly 8

Key Safety Concerns:

• Renal toxicity: Monitor kidney function, especially in patients with baseline renal impairment 1, 6
• Bone density: May cause decreased bone mineral density 6
• Do NOT use Truvada alone in patients with HIV infection—it must be combined with other antiretrovirals 1
• Ensure patients do not run out of medication to prevent HBV flare-ups in co-infected individuals 1

Common Pitfalls to Avoid:

• Never initiate PrEP without recent HIV testing to avoid inadvertently treating undiagnosed HIV with dual-drug therapy, which promotes resistance 7
• Do not use on-demand PrEP for women or people who inject drugs—only validated for MSM with receptive anal intercourse 2, 7
• Do not adjust dosing for bariatric surgery or other surgical procedures—continue daily dosing throughout the perioperative period 9