Viread (tenofovir)

How does it work?

Viread tablets contain the active ingredient tenofovir disoproxil fumarate, which is a type of medicine called a nucleotide reverse transcriptase inhibitor. It is used in the treatment of HIV (human immunodeficiency virus) infection. AIDS (acquired immune deficiency syndrome) is caused by infection with HIV. This virus invades cells of the immune system, particularly the white blood cells known as CD4 T-helper lymphocytes. These cells normally work to activate other cells in the immune system to fight infection. Since HIV kills CD4 T-helper cells, over time the body becomes less able to fight the virus or subsequent infections. Once the virus is inside the CD4 T-cell it multiplies. Part of the process of viral multiplication involves the conversion of the virus genetic material, RNA, into DNA. This is achieved by a compound essential to the virus, called reverse transcriptase. Reverse transcriptase is a compound known as an enzyme. Tenofovir works by blocking the action of this enzyme, thereby interfering with the conversion of viral RNA into DNA. This stops the virus from multiplying. There is no cure for HIV, but tenofovir is one of a number of medications that lowers the amount of virus in the body (viral load) and slows the progression of the disease from HIV to AIDS. Tenofovir must be used in conjunction with other anti-HIV drugs that attack the HIV virus in different ways. It can be used as one of the first medicines to treat people who have not yet started anti-HIV medicines. It can also be added to existing treatment in people who are failing an antiretroviral regimen because their virus has become resistant, and is not responding to the existing treatment.

What is it used for?

HIV infection.

Warning!

This medicine should be taken with or after food, as food increases the absorption of the medicine into the body.

The HIV virus is very good at becoming resistant to anti-HIV medicines. For this reason it is very important that you carefully follow your doctor's instructions for taking your anti-HIV medicines, in order to maintain effective levels of the medicines in your blood. If the blood levels drop, the virus will be given more chance to replicate and develop resistance to the drugs. Skipping even a few doses increases the risk of treatment failure, so you should try to ensure that you take all your doses at the correct time, and that you visit your doctor for repeat prescriptions before you run out.

Treatment of HIV infection with anti-HIV medicines such as this one does not reduce the risk of transmitting the virus to other people through sexual contact or blood contamination. You should continue to use condoms to prevent transmitting the virus to your sexual partner.

If you have any problems with your liver, in particular chronic hepatitis B or C, your liver function should be monitored while you are taking this medicine.

Your kidney function should be monitored prior to starting and regularly throughout treatment with this medicine. Monitoring is recommended every four weeks during the first year of treatment, and then every three months. Your doctor may want to monitor your kidney function more frequently than this if you already have, or are at risk of, kidney problems.

The class of medicines that tenofovir is related to can cause a rare but serious condition called lactic acidosis, which is an excess of lactic acid in the blood, together with an enlarged liver. This side effect is more likely to occur in overweight women and people with liver disease (particularly hepatitis C treated with alpha interferon and ribavirin). If it occurs, lactic acidosis usually develops after a few months of treatment. Your doctor will monitor you for this side effect, but symptoms that might indicate it's development include rapid and/or deep breathing and non-specific symptoms such as feeling weak, sick or generally unwell, vomiting, abdominal pain, loss of appetite or weight loss. You should tell your doctor if you experience any of these.

Combination antiretroviral therapy has been associated with a redistribution of body fat (lipodystrophy) in people with HIV. This may include loss of fat from the face and limbs, increased fat in the abdomen and internal organs, breast enlargement and fatty lumps at the back of the neck (buffalo hump). The long-term consequences of this are currently unknown, however your doctor may wish to monitor your body fat, and the levels of lipids (eg cholesterol) and sugar (glucose) in your blood, and may prescribe additional medicines for any lipid disorders that occur during treatment with this medicine. Contact your doctor if you notice any changes in your body fat during treatment with your HIV medicines.

Some people being treated with combination antiretroviral therapy may develop a bone condition called osteonecrosis. This condition is caused by loss of blood supply to a bone, causing death of the bone tissue. The risk of the condition is thought to be increased by corticosteroid use, alcohol consumption, severe immunosuppression, higher body mass index, advanced HIV disease and long-term use of antiretroviral medicines. If you notice any joint stiffness, aches and pains (especially of the hip, knee and shoulder) or difficulty in movement while using this medicine, you should tell your doctor so this can be investigated.

The safety and efficacy of this medicine have not been studied in children and adolescents under 18 years of age, or in elderly people over 65 years of age. It is not recommended for these age groups.

Use with caution in

Decreased kidney function

People at risk of or with a history of kidney problems

Elderly people

Obese women

Liver disease

Enlarged liver (hepatomegaly)

Hepatitis, especially chronic hepatitis B or C

History of alcohol abuse.

Not to be used in

Allergy to any ingredient.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

The safety of this medicine during pregnancy has not been investigated. Since the effects on a developing foetus are unknown, women who could get pregnant should use effective contraception while taking this medicine. The medicine should not be used during pregnancy unless the benefits outweigh the potential risks to the foetus. Seek medical advice from your doctor.

It is recommended that women infected with the HIV virus should not breastfeed their infants under any circumstances, and regardless of their treatment, in order to avoid passing the virus to the baby via their breast milk. Seek further medical advice from your doctor.

Label warnings

Take this medication with or after food.

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