Rifater

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How does it work?

This medication contains three different compounds which act together to kill bacteria that cause tuberculosis (TB). Rifampicin targets and inactivates a bacterial chemical called RNA-polymerase. The tuberculosis bacteria use RNA-polymerase to make essential proteins and to copy their own genetic information (DNA). Without this chemical the bacteria cannot reproduce and they die. Isoniazid's exact mechanism of action is unknown but it is thought to prevent the bacteria from making components called mycolic acids which are needed to form cell walls. It also seems to combine with an enzyme which interferes with the cell metabolism of the bacteria. As a result of the disruption in it's metabolism and without a cell wall the bacteria die. Pyrazinamide when it enters a tuberculosis infected cell sets off a chain of chemical reactions that kills the bacteria. There are two stages in the treatment of tuberculosis. In the first two months after infection (the initial phase), treatment is aimed at killing as many bacteria as possible. Therefore several anti-TB drugs with different mechanisms of action are used in combination. After this time some of the medications are stopped and the others are continued for a further four months (continuation phase) to kill any remaining bacteria. Rifampicin and isoniazid are used in both stages of treatment whilst pyrazinamide is used in the inital phase of treatment only. The bacteria that cause TB are difficult to treat. By using medications in combiation, the bacteria can be targeted in different ways and hence treatment is more likely to be effective than a single medicine alone. In addition, using different medications make it less likely that bacteria will develop resistance to treatment. As the period of treatment is long the combination of the three drugs in one tablet helps compliance with the treatment.

What is it used for?

- Initial treatment of TB

Warning!

- People taking this medicine should have regular blood tests.
- Discolours contact lenses
- Your liver functioning should be monitored while you are taking this medicine. Symptoms that may suggest a liver problem include persistent nausea and vomiting, abdominal pain, or the development of jaundice (a yellow colouring to the skin and the whites of the eyes). Consult your doctor if you experience any of these symptoms.
- This medicine reduces the effectiveness of the oral contraceptive pill. Additional precautions should be taken to avoid pregnancy (seek advice).
- As isoniazid can cause peripheral neuropathy (peripheral neuritis) as a side effect, pyridoxine (Vitamin B6) is often prescribed to help prevent this.

Use with caution in

- Alcoholism
- Children
- Decreased kidney function
- Decreased liver function
- Diabetes
- Epilepsy
- Gout
- History of psychotic illness
- Slow liver metabolism (slow acetylator status)

Not to be used in

- Jaundice
- Life long inherited blood diseases which can cause a variety of symptoms, including mental health problems (porphyrias)
- Liver disease

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.

- There is no information available about the safety of this medicine during pregnancy, therefore it is not recommended for use during pregnancy, unless considered essential by your doctor. Seek medical advice from your doctor.
- This medicine should be used with caution by breastfeeding mothers, and only if the expected benefit to the mother is greater than any possible risk to the baby. Seek medical advice from your doctor.

Label warnings

- Do not stop taking this medication except on your doctor's advice.
- Take this medication half to one hour before food.
- This medication may cause your urine to be coloured.

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