What labs are required for Truvada (Emtricitabine/Tenofovir Disoproxil Fumarate) for Pre-Exposure Prophylaxis (PrEP)?

From the Guidelines

Truvada for preventative use requires initial and regular laboratory tests, including a combined HIV antibody and antigen test, estimated creatinine clearance rate, genital and nongenital gonorrhea and chlamydia testing, syphilis testing, and pregnancy testing for individuals of childbearing potential, as recommended by the 2020 International Antiviral Society-USA panel 1. When initiating Truvada for PrEP, the following labs are necessary:

• Combined HIV antibody and antigen test to confirm negative HIV status
• Estimated creatinine clearance rate to assess kidney function
• Genital and nongenital gonorrhea and chlamydia testing by NAAT
• Syphilis testing
• Pregnancy testing for individuals of childbearing potential After starting Truvada, regular follow-up tests are required, including:
• Quarterly: combined HIV antibody and antigen test, estimated creatinine clearance rate (at first quarterly visit and annually thereafter), genital and nongenital gonorrhea and chlamydia testing, syphilis testing, and pregnancy testing for individuals of childbearing potential
• Annually: combined HIV antibody and antigen test, estimated creatinine clearance rate, and hepatitis C virus antibody test (every 3–6 months for people who inject drugs and MSM who use recreational drugs at the time of sex if liver function test results are abnormal) 1. These laboratory tests are crucial to ensure the safe and effective use of Truvada for HIV prevention, as they help monitor kidney function, detect potential HIV infection, and identify other sexually transmitted infections 1.

From the FDA Drug Label

Laboratory Abnormalities: Laboratory abnormalities observed in Trial 934 were generally consistent with those seen in previous trials (Table 5).

Table 5 Significant Laboratory Abnormalities Reported in ≥1% of Subjects in Any Treatment Group in Trial 934 (0 to 144 Weeks)

Emtricitabine + TDF + EFV AZT/3TC + EFV N=257 N=254 Any ≥ Grade 3 Laboratory Abnormality 30% 26% Fasting Cholesterol (>240 mg/dL) 22% 24% Creatine Kinase(M: >990 U/L)(F: >845 U/L) 9% 7% Serum Amylase (>175 U/L) 8% 4% Alkaline Phosphatase (>550 U/L) 1% 0% AST(M: >180 U/L)(F: >170 U/L) 3% 3% ALT(M: >215 U/L)(F: >170 U/L) 2% 3% Hemoglobin (<8. 0 mg/dL) 0% 4% Hyperglycemia (>250 mg/dL) 2% 1% Hematuria (>75 RBC/HPF) 3% 2% Glycosuria (3+) <1% 1% Neutrophils (<750/mm3) 3% 5% Fasting Triglycerides (>750 mg/dL) 4% 2%

The labs required for Truvada for preventative use are not explicitly stated in the provided drug label. However, based on the laboratory abnormalities reported in the trials, the following labs may be relevant:

• Complete Blood Count (CBC): to monitor for neutrophils (<750/mm3) and hemoglobin (<8.0 mg/dL)
• Liver Function Tests (LFTs): to monitor for ALT (>215 U/L) and AST (>180 U/L)
• Lipid Profile: to monitor for fasting cholesterol (>240 mg/dL) and fasting triglycerides (>750 mg/dL)
• Serum Amylase: to monitor for (>175 U/L)
• Creatine Kinase: to monitor for (>990 U/L)
• Urinalysis: to monitor for hematuria (>75 RBC/HPF) and glycosuria (3+)
• Fasting Glucose: to monitor for hyperglycemia (>250 mg/dL) It is essential to note that these labs are not explicitly required for Truvada preventative use, and the decision to monitor these labs should be made on a case-by-case basis, considering the individual patient's risk factors and medical history 2.

From the Research

Labs Required for Truvada for Preventative Measures

To determine the labs required for Truvada as a preventative measure, we need to consider the following:

• Truvada is used for pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV-1 in high-risk adults 3.
• The US Food and Drug Administration (FDA) approved Truvada for PrEP in 2012, based on two randomized controlled trials (RCTs) 4.
• Before starting Truvada for PrEP, the following labs are typically required:
  • HIV testing to confirm the individual is HIV-negative
  • Hepatitis B virus (HBV) testing, as HBV infection can affect liver function and interact with Truvada 5, 6
  • Kidney function tests, such as serum creatinine and estimated glomerular filtration rate (eGFR), to monitor for potential kidney damage
  • Liver function tests, such as alanine transaminase (ALT) and aspartate transaminase (AST), to monitor for potential liver damage
• Regular monitoring of these labs is also recommended while taking Truvada for PrEP, typically every 3-6 months 3, 4.

Additional Considerations

• Individuals taking Truvada for PrEP should also be screened for other sexually transmitted infections (STIs) and receive counseling on safer sex practices 3, 4.
• The use of Truvada for PrEP has been shown to be effective in reducing the risk of HIV transmission, but it is not a substitute for other preventative measures, such as condoms and safer sex practices 3, 4.