Tenofovir Disoproxil Fumarate (TDF)
Originally developed by Gilead Sciences Inc. under the brand name Viread, tenofovir disoproxil fumarate, or TDF, treats HIV-1 and chronic hepatitis B virus infections. When used for pre-exposure prophylaxis, or PrEP, the medicine may prevent HIV infection. Gilead sells five different TDF brand name drugs in the United States, and the drug also comes in generic form.
Tenofovir disoproxil fumarate, also called TDF or tenofovir DF, is a prescription drug that treats human immunodeficiency virus (HIV) infection and hepatitis B virus (HBV) infection in adults and children. The U.S. Food and Drug Administration also approved a brand of the drug to help prevent HIV infection, a practice known as pre-exposure prophylaxis, or PrEP.
The agency approved the first brand name drug, Viread, manufactured by Gilead Sciences Inc. in 2001. Since then, Gilead has manufactured several TDF drugs in combination with other anti-HIV medications. According to the company’s 2018 annual report, it achieved record sales for its HIV products in 2018, and sales of HIV treatments accounted for 67 percent of its total product sales.
Gilead’s current brand name TDF drugs include: Viread, Truvada, Atripla, Complera and Stribild.
Common side effects of TDF drugs include rash, diarrhea, headache, pain, depression, asthenia and nausea. The most serious side effects include decreases in bone density, liver problems, kidney problems, lactic acidosis and worsening HBV symptoms after stopping treatment.
The drug has also had its share of controversy.
In 2002 and 2003, the FDA ordered Gilead to stop downplaying Viread’s risks and exaggerating its benefits, The Los Angeles Times reported. A Gilead salesperson even told an FDA official that Viread was “a miracle drug.”
In 2016, AIDS Healthcare Foundation accused Gilead of intentionally delaying the release of a stronger, safer medication called tenofovir alafenamide (TAF) to maximize profits from TDF. People who suffered kidney disease or bone density loss filed TDF lawsuits claiming the drug maker’s delay in releasing TAF caused patients to suffer from serious side effects unnecessarily.
How Does TDF Work?
TDF is a nucleoside reverse transcriptase inhibitor (NRTI). Reverse transcriptase is an HIV enzyme. Drugs like TDF work by blocking this enzyme. By blocking the enzyme, the drug prevents HIV from multiplying. It may also reduce the amount of HIV in the body.
TDF is not a cure for HIV/AIDS, but an HIV treatment regimen can help infected people live longer. It also reduces the risk of transmitting the disease to others.
It also blocks HBV reverse transcriptase and works similarly for people with HBV.
How Effective Is It?
In several clinical trials, researchers found TDF in combination with other antiretroviral drugs reduced the amount of HIV or HBV in the blood, known as the viral load, in patients with the infections.
In one study called Trial 903, researchers randomized 600 patients with HIV-1 who had never been treated to receive Viread with lamivudine (3TC) and efavirenz (EFV), or stavudine (d4T), 3TC, and EFV. Patients in the two groups had similar results.
The average starting HIV-1 viral load was 77,600 copies/mL. At week 144, patients achieved an HIV-1 concentration of less than 400 copies/mL.
Brand Names and Dosages
Gilead is the main manufacturer and marketer of TDF HIV drugs in the United States. After it developed TDF, it began creating combination drugs. Each is slightly different, but they all work similarly.
Viread (tenofovir disoproxil fumarate)
Viread was Gilead’s original TDF drug. The FDA approved it in 2001. In combination with another antiretroviral, it treats HIV-1 infection in adults and children 2 years old or older who weigh at least 22 lbs. Viread alone can treat HBV in adults and children 2 years old or older who weigh at least 22 lbs.
It comes in a pill or powder form.
- 150 mg, 200 mg, 250 mg, and 300 mg
- Oral Powder:
- 40 mg per 1 g of oral powder
- Tablet dosage in adults and pediatric patients who weigh at least 77 lbs: One 300 mg tablet once daily taken orally with or without food; this may be adjusted for body weight
- Oral Powder
- For patients who weigh at least 37.5 lbs and unable to swallow a tablet, 8 mg of TDF per kilogram of body weight (up to a maximum of 300 mg) taken once daily in soft food such as applesauce, baby food or yogurt
- Creatinine clearance (CrCl) 50 or greater:
- 300 mg every 24 hours
- CrCl 30 to 49 mL/min:
- 300 mg every 48 hours
- CrCl 10 to 29 mL/min:
- 300 mg every 72 to 96 hours
- Hemodialysis patients:
- 300 mg every 7 days or after approximately 12 hours of dialysis
Truvada (emtricitabine and tenofovir disoproxil fumarate)
Truvada combines TDF with emtricitabine, another antiretroviral. The FDA approved it in 2004. Unlike with Viread, the FDA did not approve Truvada to treat HBV. Doctors prescribe it with other antiretrovirals to treat existing HIV-1 in adults and pediatric patients. Patients may also take it as HIV-1 pre-exposure prophylaxis (PrEP) to reduce the risk of contracting the virus.
Prior to taking Truvada, doctors must test patients for HBV and HIV infection.
Tablets: 200 mg/300 mg, 167 mg/250 mg, 133 mg/200 mg, and 100 mg/150 mg of emtricitabine and tenofovir disoproxil fumarate, respectively.
- Recommended dosage in adults and pediatric patients who weigh at least 77 lbs: One tablet containing 200 mg of emtricitabine and 300 mg of TDF once daily taken with or without food
- In pediatric patients who weigh at least 37.5 lbs: One low-strength tablet (100 mg/150 mg, 133 mg/200 mg, or 167 mg/250 mg based on body weight) once daily with or without food
- Creatinine clearance (CrCl) 30 to 49 mL/min: One tablet every 48 hours
- Patients with CrCl below 30 mL/min or on hemodialysis should not take Truvada.
- Recommended dosage in HIV-1 uninfected adults and adolescents who weigh at least 77 lbs: One tablet once daily with or without food.
- Renally impaired HIV-uninfected people should not take Truvada if CrCl is below 60 mL/min.
Atripla (efavirenz, emtricitabine, and tenofovir disoproxil fumarate)
Atripla combines TDF with two other drugs to treat HIV-1 infection in adults and children who weigh at least 88 lbs. The FDA approved it in 2006.
Tablets: 600 mg of efavirenz, 200 mg of emtricitabine, and 300 mg of tenofovir disoproxil fumarate
The recommended dosage for adults and children who weigh at least 88 lbs is one tablet once a day on an empty stomach at bedtime. For patients who weigh 110 lbs or more, add an additional 200 mg a day of efavirenz. Patients with kidney problems with creatinine clearance below 50 mL/min should not use this drug.
Complera (emtricitabine, rilpivirine hydrochloride, and tenofovir disoproxil fumarate)
Complera combines TDF with two other drugs to treat HIV-1 in adults and children who weigh at least 77 lbs with a viral load of 100,000 copies/mL or less. The FDA approved it in 2011.
Tablets: 200 mg of emtricitabine, 25 mg of rilpivirine, and 300 mg of tenofovir disoproxil fumarate
The recommended dosagefor adults and children who weigh at least 77 lbs is one tablet daily with food. Patients with kidney problems with creatinine clearance below 50 mL per minute should not take Complera.
Stribild (elvitegravir, cobicistat, emtricitabine, and tenofovir disoproxil fumarate)
Stribild combines TDF with three other drugs to treat HIV-1 in adults and children who are 12 years old or older and weigh at least 77 lbs. The FDA approved it in 2012.
Tablets: 150 mg of elvitegravir, 150 mg of cobicistat, 200 mg of emtricitabine, and 300 mg of tenofovir disoproxil fumarate.
The recommended starting dosage for adults and children who are 12 years old or older and weigh at least 77 lbs is one tablet daily with food. Patients with kidney problems with creatinine clearance below 70 mL per minute should start treatment.
Some drugs can interact with TDF and increase or decrease its strength. Drug interactions can cause additional side effects or prevent the drugs from working effectively.
- Taking TDF with didanosine increases didanosine concentrations. It may cause symptoms of didanosine toxicity such as pancreatitis or neuropathy.
- HIV-1 protease inhibitors
- When taken with atazanavir and ritonavir, darunavir and ritonavir, or lopinavir/ritonavir, tenofovir concentrations increase. Monitor for evidence of tenofovir toxicity.
- Hepatitis C Antiviral Agents
- Drugs such as Epclusa and Harvoni increase concentrations of TDF and may cause increased adverse reactions.
- Drugs Affecting Renal Function
- Because the kidneys eliminate TDF, drugs that reduce kidney function can increase blood concentration of TDF. Examples include: cidofovir, acyclovir, valacyclovir, ganciclovir, valganciclovir, gentamicin, and high-dose or multiple NSAIDs. TDF should not be used with Hespera.
Each combination drug will have its own additional interactions. Please check the individual drug label for each specific medication.
Please seek the advice of a medical professional before making health care decisions.