Tenofovir

Tenofovir is a prescription medication used along with other medications to treat human immunodeficiency virus (HIV) and hepatitis B infections. Tenofovir belongs to a group of drugs called nucleoside reverse transcriptase inhibitors (NRTIs) which work by stopping the virus from replicating.

This medication comes in tablet form and in an oral powder to be mixed with soft food that does not require chewing (applesauce). Tenofovir is taken once daily. Tenofovir tablets can be taken with or without food.

Common side effects of tenofovir include nausea, rash, and diarrhea.

Tenofovir is a prescription medicine used:

• with other antiviral medicines to treat Human Immunodeficiency Virus (HIV) in adults and children 2 years of age and older. 
• to treat chronic hepatitis B virus (HBV) in adults. Tenofovir will not cure HBV.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Take tenofovir exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

Recommended Dose in Adults

For the treatment of HIV-1 or chronic hepatitis B: The dose is one 300 mg tenofovir tablet once daily taken orally, without regard to food.

For adults unable to swallow tenofovir tablets, the oral powder formulation (7.5 scoops) may be used.

In the treatment of chronic hepatitis B, the optimal duration of treatment is unknown.

Recommended Dose in Pediatric Patients (2 to Less Than 18 Years of Age)

For the treatment of HIV-1 in pediatric patients 2 years of age and older, the recommended oral dose of tenofovir is 8 mg of tenofovir disoproxil fumarate per kilogram of body weight (up to a maximum of 300 mg) once daily administered as oral powder or tablets.

Tenofovir oral powder should be measured only with the supplied dosing scoop. One level scoop delivers 1 g of powder which contains 40 mg of tenofovir disoproxil fumarate. Tenofovir oral powder should be mixed in a container with 2 to 4 ounces of soft food not requiring chewing (e.g., applesauce, baby food, yogurt). The entire mixture should be ingested immediately to avoid a bitter taste. Do not administer tenofovir oral powder in a liquid as the powder may float on top of the liquid even after stirring. Further patient instructions on how to administer tenofovir oral powder with the supplied dosing scoop are provided in the FDA-approved patient labeling (Patient Information).

Tenofovir is also available as tablets in 150, 200, 250 and 300 mg strengths for pediatric patients who weigh greater than or equal to 17 kg and who are able to reliably swallow intact tablets. The dose is one tablet once daily taken orally, without regard to food. Weight should be monitored periodically and the tenofovir dose adjusted accordingly.

WARNINGS: LACTIC ACIDOSIS/SEVERE HEPATOMEGALY WITH STEATOSIS and POST TREATMENT EXACERBATION OF HEPATITIS

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs, including tenofovir, in combination with other antiretrovirals.

Severe acute exacerbations of hepatitis have been reported in HBV-infected patients who have discontinued anti-hepatitis B therapy, including tenofovir. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-hepatitis B therapy, including tenofovir. If appropriate, resumption of anti-hepatitis B therapy may be warranted.

Tenofovir can cause serious side effects, including:

• feeling very weak or tired
• have unusual (not normal) muscle pain
• have trouble breathing
• have stomach pain with
  • nausea (feel sick to your stomach)
  • vomiting
• feel cold, especially in your arms and legs
• feel dizzy or lightheaded
• have a fast or irregular heartbeat

• Your skin or the white part of your eyes turns yellow (jaundice).
• dark "tea-colored" urine
• light-colored bowel movements (stools)
• loss of appetite for several days or longer
• nausea
• stomach pain

You may be more likely to get lactic acidosis or severe liver problems if you are female, very overweight (obese), or have been taking tenofovir for a long time.

• New or worse kidney problems can happen in some people who take tenofovir. If you have had kidney problems in the past or need to take another medicine that can cause kidney problems, your healthcare provider may need to do blood tests to check your kidneys during your treatment with tenofovir.
• Bone problems can happen in some people who take tenofovir. Bone problems include bone pain, softening or thinning (which may lead to fractures). Your healthcare provider may need to do additional tests to check your bones.
• Changes in body fat can happen in some people who take antiviral medicines. These changes may include increased amount of fat in the upper back and neck ("buffalo hump"), breast, and around the main part of your body (trunk). Loss of fat from the legs, arms, and face may also happen. The cause and long-term health effects of these conditions are not known.
• Changes in your immune system (Immune Reconstitution Syndrome) can happen when you start taking HIV medicines. Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your healthcare provider if you start having new symptoms after starting your HIV medicine.

• Do not let your tenofovir run out. Refill your prescription or talk to your healthcare provider before your tenofovir is all gone.
• Do not stop taking tenofovir without first talking to your healthcare provider.
• If you stop taking tenofovir, your healthcare provider will need to check your health often and do blood tests regularly to check your HBV infection. Tell your healthcare provider about any new or unusual symptoms you may have after you stop taking tenofovir. 
• Talk to your doctor about taking an HIV test before starting treatment with tenofovir for chronic hepatitis B. You should also get a test for HBV if you are taking tenofovir for treatment of HIV.

Tenofovir may cause serious side effects. See "Drug Precautions" section.

The most common side effects in all people who take tenofovir are:

• nausea
• rash
• diarrhea
• headache
• pain
• depression
• weakness

In some people with advanced HBV-infection, other common side effects may include:

• sleeping problems
• itching
• vomiting
• dizziness
• fever

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of tenofovir. For more information, ask your healthcare provider or pharmacist.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. Tenofovir may affect the way other medicines work, and other medicines may affect how tenofovir works.

Do not take tenofovir if you also take:

• other medicines that contain tenofovir (Atripla, Complera, Truvada)
• adefovir (Hepsera)

Especially tell your healthcare provider if you take the following medications, as the dose of these other medications may need to be changed:

• didanosine (Videx)
• atazanavir (Reyataz)
• lopinavir with ritonavir (Kaletra)

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category B. It is not known if tenofovir will harm your unborn baby. There is a pregnancy registry for women who take antiviral medicines during pregnancy. Its purpose is to collect information about the health of you and your baby. Talk to your healthcare provider about how you can take part in this registry.

Do not breastfeed if you are taking tenofovir. Tenofovir passes into your breast milk. You should not breastfeed because of the risk of passing HIV to your baby. Talk to your healthcare provider about the best way to feed your baby.

Changes in body fat can happen in some people who take antiviral medicines.

• These changes may include increased amount of fat in the upper back and neck ("buffalo hump"), breast, and around the main part of your body (trunk).
• Loss of fat from the legs, arms, and face may also happen.

When your tenofovir supply starts to run low, get more from your healthcare provider or pharmacy. It is very important not to run out of this medication. The amount of virus in your blood may increase if the medicine is stopped for even a short time.

Patients who are unable to swallow tenofovir tablets whole may take tenofovir oral powder. Ask your pharmacist or doctor about the oral powder.

Avoid doing things that can spread infection to others:

• Do not share needles or other injection equipment.
• Do not share personal items that can have blood or body fluids on them, like toothbrushes and razor blades.
• Do not have any kind of sex without protection.
• Do not breastfeed.