Information About Tenofovir

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What Is Tenofovir

Tenofovir, also called tenofovir disoproxil fumarate, is an antiviral drug for treating chronic hepatitis B (HBV) in adults and children who are 12 years and older. It is also used, in combination with other drugs, to treat the human immunodeficiency virus, or HIV. It's sold under the brand name Viread by Gilead Sciences, Inc. 

How Tenofovir Works

HBV is a noncytopathic virus, which means the virus itself does not directly damage the liver.

Rather, when the body is infected with HBV, the immune system mounts an assault on the virus, and causes collateral damage in the form of inflammation and damage to the liver. Tenofovir is part of a class of medications known as nucleoside reverse transcriptase inhibitors (NRTIs). These work by decreasing the amount of the hepatitis B virus in the blood, which in turn keeps the immune response at bay. It will not cure hepatitis B, may not prevent complications of the disease such as cirrhosis of the liver or liver cancer, and will not prevent the spread of the virus to others. 

Other Names for Tenofovir

There are no generic drugs available.

Effectiveness

Tenofovir can treat hepatitis B very effectively in some people. In some situations, tenofovir is more effective than adefovir and lamivudine. Recent research suggests tenofovir is a safe and effective long-term treatment for HBV, especially for people who have developed resistance to lamivudine.

In addition, this research suggests it leads to few kidney-related side effects and no clinically relevant bone loss.

How to Take Tenofovir

Viread is a 300 mg tablet. For chronic hepatitis B, the usual dosing for adults is 300 mg once a day and can be taken with or without food. This dosage might change for people with kidney problems.

Costs of Tenofovir

One year of treatment with tenofovir can easily cost more than $8,000. However, drug costs vary considerably based on many factors, such as whether you have health insurance, where you live and which pharmacy you use.

Side Effects of Tenofovir

Possible side effects of tenofovir include:

  • Diarrhea
  • Headache
  • Depression
  • Rash
  • Itching
  • Fever
  • Difficulty falling asleep or staying asleep
  • Gas
  • Weight loss

In addition, serious liver complications as well as a condition known as lactic acidosis can develop rarely in patients taking tenofovir. If you experience the following symptoms while taking tenofovir, you should call your physician or seek emergency medical care: 

  • Persistent nausea and/or vomiting
  • Stomach/abdominal pain
  • Pale stools
  • Dark urine
  • Jaundice (yellowing of the eyes and/or skin)
  • Extreme fatigue
  • Rapid or difficult breathing
  • Drowsiness
  • Muscle pain and/or weakness
  • Cold skin

Who Should Not Take Tenofovir

Anyone who is allergic to tenofovir shouldn't take this drug. Also, it's important to know your HIV status because taking tenofovir can significantly complicate treating HIV.

If you have HIV and HBV, do not start therapy for either infection without consulting a physician experienced in treating both infections. Tenofovir is classified as a category B drug for use in pregnancy, which means there is no evidence to suggest it is harmful to a pregnant mother or her fetus. 

Source:

U.S. Food and Drug Administration. Viral Hepatitis Therapies. Accessed February 22, 2010.

UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2010.

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