Author: Glaxo Group Ltd.

Long information

What is it and how is it used?

Zeffix belongs to a group of medicines called antivirals. It is used for the treatment of hepatitis B virus infection. Hepatitis B is a virus which infects the liver, and leads to liver damage. Zeffix can be used in people whose liver is damaged but still functions ( compensated liver disease) and in people whose liver is damaged and does not function normally ( decompensated liver disease).

Zeffix is used to treat patients 18 years of age or over with long term (chronic) hepatitis B.

Treatment with Zeffix can reduce the amount of hepatitis B virus in your body. This should lead to a reduction in liver damage and an improvement in your liver function.


Table of Contents
What do you have to consider before using it?
How is it used?
What are possible side effects?
How should it be stored?
Further information

What do you have to consider before using it?

Do not take Zeffix:

  • if you are allergic (hypersensitive) tolamivudine or to any of the other ingredients of Zeffix.

If you are not sure please consult your doctor.

Take special care with Zeffix

Zeffix reduces the amount of hepatitis B virus in your body, and keeps the liver disease under control, therefore reducing health problems relating to your liver in the future. For effective treatment you will need to take Zeffix every day. Patients respond to the treatment differently, therefore it is not known for how long you will have to take this medicine.

Your doctor will be checking your response to treatment by taking regular blood samples. The results of these tests will help your doctor to decide when your treatment with Zeffix can be stopped.

Before treatment with Zeffix you should have discussed any additional medical problems that you have with your doctor. If you have kidney disease the dose of this medicine may have to be reduced, as it is your kidneys that are mainly responsible for getting rid of the medicine from your body. Zeffix is also available as an oral solution. This means that your doctor can prescribe a lower dose for you if necessary.

Do not stop taking Zeffix without instruction from your doctor, as there is a small risk of your hepatitis getting worse. When you stop taking Zeffix your doctor will monitor you for at least the following four months to check for any problems. This will mean taking blood samples to check for any abnormal liver enzymes, indicating liver damage.

The active substance in Zeffix is lamivudine. If you are already taking this medicinal product for HIV infection, your doctor will continue to treat you with the higher dose, usually 150 mg twice a day, as the lower dose of 100 mg lamivudine is insufficient to treat HIV infection.

Because your medicine helps to control your hepatitis B and it is not yet known whether it will cure it, you are still at risk of transmitting this virus to others through sexual contact or by blood transfer, and you should use appropriate precautions to prevent this. There is an effective vaccine available to protect those at risk from becoming infected with hepatitis B virus.

The class of medicines to which Zeffix belongs (NRTIs) can cause a condition called lactic acidosis (build up of lactic acid in the body), together with an enlarged liver. Lactic acidosis, if it occurs, usually develops after a few months of treatment. Deep, rapid breathing, drowsiness, and non specific symptoms such as nausea, vomiting and stomach pain, might indicate the development of lactic acidosis. This rare, but serious side effect occurs more often in women, particularly if very overweight. As you have liver disease you may also be more at risk of getting this condition. While you are being treated with Zeffix your doctor will monitor you closely for any signs that you may be developing lactic acidosis.

Taking other medicines

Some medicines may affect the action of Zeffix. Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription.

Zeffix should not be taken with:

  • zalcitabine or lamivudine (used to treat HIV infection)
  • emtricitabine (used to treat HIV or hepatitis B infection).

Taking Zeffix with food and drink

Zeffix can be taken with food or on an empty stomach.


Ask your doctor or pharmacist for advice before taking any medicine.
Tell your doctor if you are pregnant, or are planning to become pregnant, or if you are breast-feeding. Your doctor will advise whether you should continue to take Zeffix while you are pregnant. Do not stop treatment with Zeffix without your doctor?s advice.

The ingredients in Zeffix can pass into breast-milk. If you are breast-feeding, you must check with your doctor before you take Zeffix.

Driving and using machines

No studies on the effect of Zeffix on the ability to drive and use machines have been performed.


How is it used?

Always take Zeffix exactly as your doctor has told you. You should check with your doctor or pharmacist if you are not sure.

The recommended dose of Zeffix is one tablet (100 mg lamivudine) once a day. The tablet should be swallowed whole with water. It can be taken with food or on an empty stomach.

Your doctor will advise you on how long you will need to take the medicine for.

Your doctor may need to reduce your dose of Zeffix if you have kidney problems. It may be necessary for you to take an oral solution instead of tablets so that the dose of your medicine can be accurately reduced.

If you take more Zeffix than you should
Accidentally taking too much of your medicine is unlikely to cause any serious problems. However, you should tell your doctor or your pharmacist, or contact your nearest hospital emergency department for further advice.

If you forget to take Zeffix
If you forget to take your medicine, take it as soon as you remember and then continue to take it as instructed. Do not take a double dose to make up for forgotten individual doses.

If you stop taking Zeffix

You must not stop taking Zeffix without consulting your doctor (see section 2).

If you have any further questions on the use of this product, ask you doctor or pharmacist.

What are possible side effects?

Like all medicines, Zeffix can cause side effects, although not everybody gets them. Side effects reported in Zeffix clinical trials were tiredness, respiratory tract infections, throat discomfort, headache, stomach discomfort and pain, nausea, vomiting and diarrhoea, increases in liver enzymes and enzymes produced in the muscles (see below).

Some people may be allergic to medicines. If you have any of the following symptoms soon after taking Zeffix STOP taking the medicine and tell your doctor immediately:
* Sudden wheeziness and chest pain or tightening.
* Swelling of eyelids, face or lips.
* Skin rash or ?hives? anywhere on the body.

Side effects thought to be caused by Zeffix are listed below:

Very common side effects
These may affect more than 1 in 10 people

  • Increases in enzymes produced by the liver called transaminases

Common side effects
These may affect up to 1 in 10 people

  • Increases in an enzyme called creatine phosphokinase produced in the muscles
  • Cramps and muscle pains

Other side effects
Other side effectshave occurred in a very small number of people but their exact frequency is unknown

  • Reductions in platelets, blood cells important for blood clotting. If you have a low platelet count you may notice you bruise more easily
  • Breakdown of muscle
  • Marked worsening of liver disease after Zeffix is stopped or during treatment if resistance develops. This can be fatal in some patients.

If any of the side effects gets serious, or you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist.

How should it be stored?

Keep out of the reach and sight of children.

Do not use Zeffix after the expiry date which is stated on the tablet carton and blister pack.

Do not store above 30 °C.

Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.

Further information

What Zeffix contains

The active substance is lamivudine. Each film-coated tablet contains 100 mg of lamivudine.

The other ingredients are: microcrystalline cellulose, sodium starch glycolate, magnesium stearate, hypromellose, titanium dioxide, macrogol 400, polysorbate 80, synthetic yellow and red iron oxide .

What Zeffix looks like and contents of the pack

Zeffix film-coated tablets are supplied in tamper evident foil blister packs containing 28 or 84 tablets.The tablets are butterscotch coloured, capsule shaped, biconvex and engraved ?GX CG5? on one face.

Not all pack-sizes may be marketed.

Marketing Authorisation Holder and Manufacturer

Manufacturer Marketing Authorisation Holder

Glaxo Wellcome Operations Glaxo Group Ltd Priory Street Ware Herts SG12 0DJ United Kingdom Greenford Road Greenford Middlesex UB6 0NN United Kingdom


Pharmaceuticals S.A.
ul. Grunwaldzka 189
60-322 Poznan

For any information about this medicinal product, please contact the local representative of the Marketing Authorisation Holder:

BelgiëBelgiqueBelgien GlaxoSmithKline s.a.n.v. TélTel 32 02 656 21 11 LuxembourgLuxemburg GlaxoSmithKline s.a.n.v. BelgiqueBelgien TélTel 32 02 656 21 11

Te. 359 2 953 10 34 Magyarország GlaxoSmithKline Kft. Tel. 36 1 225 5300

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Tel: + 370 5 264 90 00

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