Emtricitabine / Tenofovir Disoproxil

This combination is used for HIV-1 treatment and, for the Truvada brand, prevention.

• Treatment of HIV-1 infection, together with other antiretroviral medicines, in adults and children weighing at least 17 kg (Truvada).
• Pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV-1 in adults at high risk, along with safer sex practices (Truvada).

The tablet contains two antiviral drugs, emtricitabine and tenofovir disoproxil fumarate. Both are nucleoside analog reverse transcriptase inhibitors. They block an enzyme HIV-1 needs to make copies of itself.

The tablet is swallowed once a day, with or without food. The regular tablet is for people weighing at least 35 kg, and a low-strength tablet is used for children weighing at least 17 kg. People with reduced kidney function may need a different schedule or may not be able to take it. Follow your prescriber and the label.

In people with HIV-1, common side effects include:

• Diarrhea and nausea
• Fatigue
• Headache and dizziness
• Depression
• Trouble sleeping and abnormal dreams
• Rash

In PrEP trials, headache, abdominal pain and weight decrease were more common than with placebo. Skin darkening on the palms or soles was generally mild. Report signs of kidney, liver or bone problems to your doctor.

• Boxed warning: lactic acidosis with severe liver enlargement, hepatitis B flares after stopping, and drug resistance if used for PrEP during undetected early HIV infection.
• Kidney injury, including kidney failure and Fanconi syndrome. Avoid nephrotoxic drugs.
• Decreased bone mineral density.
• Body fat redistribution and immune reconstitution syndrome.
• Not recommended as part of a triple nucleoside-only regimen, because early treatment failure has been reported.
• PrEP is not always effective, so use it with other prevention measures and take every dose.

Several medicines can change drug levels or add kidney strain.

• Other emtricitabine, tenofovir or lamivudine products: do not combine.
• Hepsera (adefovir): do not combine.
• Didanosine: levels rise, raising risk of pancreatitis and neuropathy.
• Atazanavir: levels fall, so it should be given with ritonavir.
• Lopinavir/ritonavir, darunavir/ritonavir and some hepatitis C medicines: tenofovir levels rise.
• Acyclovir, valacyclovir, ganciclovir, aminoglycosides and high-dose or multiple NSAIDs: may raise drug levels and affect the kidneys.

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

• Do not use for PrEP if HIV-1 status is unknown or positive.
• Get tested for hepatitis B before starting.
• Have kidney function and urine tests checked before and during use.
• Kidney impairment can limit use or change the dosing schedule.
• Tell your doctor about fracture history or bone loss risk.
• Pregnancy: observational data show no increased risk of major birth defects, and a pregnancy registry exists.
• Mothers with HIV-1 should not breastfeed.
• Pharmacokinetics have not been fully evaluated in people 65 and older.

If an overdose occurs, the person should be monitored for signs of toxicity and given standard supportive care. In small studies, higher-than-usual doses of the individual components did not cause severe reactions. Hemodialysis removes some of each drug.

Both drugs are absorbed after swallowing. Emtricitabine is well absorbed, with peak levels in 1 to 2 hours, and tenofovir peaks in about 1 hour. Food does not affect emtricitabine and modestly raises tenofovir, so the tablet can be taken with or without food. Both are cleared mainly by the kidneys. The half-life is about 10 hours for emtricitabine and about 17 hours for tenofovir.

Store at 25 °C (77 °F), excursions permitted to 15 °C–30 °C (59 °F–86 °F) (see USP Controlled Room Temperature).