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Treating TB
Antibiotics to treat TB have been available since the 1950s, and when used correctly they can cure TB in people with HIV.
However, like HIV, treating TB means taking a combination of drugs at the right time and in the right way. Treatment is often for six months but may last for nine months in some cases. Many people either don't take their treatment properly or stop taking their pills once they start to feel better. This can lead to TB becoming resistant to some or all of the drugs used to treat it, and multidrug-resistant TB is a growing problem worldwide. In some parts of the world doctors have given people with TB inadequate therapy in the first place, which has also caused drug resistance.
Anti-TB drugs can also interact with some drugs, including those used to treat HIV, and can have unpleasant side-effects.
Anti-TB drugs
- Clarithromycin. This drug is an antibiotic used for the treatment of the AIDS-defining illness MAI, but is also sometimes used to treat TB.
- Dapsone. An antibiotic used to treat the AIDS-defining illnesses PCP and MAI, which is also sometimes used to treat TB, particularly drug-resistant TB.
- Ethambutol. An anti-mycobacterial antibiotic which, in combination with other drugs is used as part of standard treatment TB.
- Isoniazid. An antibiotic drug which, in combination with other drugs, is a standard treatment for TB. It is also sometimes used by itself as TB prophylaxis.
- Pyrazinamide. A first-line drug for the treatment of TB in combination with other drugs.
- Rifampicin. An anti-mycobacterial drug which is included in standard anti-TB combinations.
- Rifabutin.This drug is used against the AIDS-defining illness MAI and is sometimes used as an alternative to rifampicin in anti-TB combinations.
- Streptomycin. The first effective anti-TB drug. It is now rarely used except in cases of multidrug-resistant TB. Administered by injection.
- Combinations pills. To help reduce the number of pills you need to take, some anti-TB drugs are available combined together in a single tablet. The following are available in the UK. Rifater (contains rifampicin, pyrazinamide and isoniazid), Rifinah (contains rifampicin and isoniazid), and Rimactazid (contains rifampicin and isoniazid).
Table – Commonly used anti-TB drugs
Treating active TB
In the UK, the TB treatment of choice is a combination of four antibiotics that work against TB. The treatment lasts for at least six months. For the first two months, four anti-TB drugs are used. These are isoniazid, rifampicin, pyrazinamide and ethambutol. If tests have shown that all the main drugs can treat your TB you may only require treatment with three drugs. These will be isoniazid, rifampicin and pyrazinamide.
Treatment with two drugs, normally isoniazid and rifampicin, continues for a further four months. some people take these two drugs for up to seven months. Everybody should also take a vitamin supplement called pyridoxine to stop to painful side-effect involving nerve damage in the lower legs and feet (and sometimes the hands) developing.
In some cases it may be necessary to take two drug treatment for seven months. This is particularly likely if you did not take pyrazinamide during the first two months of treatment or if TB germs can still be detected in your sputum at the end of the initial two month phase of treatment.
It is normal to take all the drugs as tablets, once daily.
As TB comes under control, normally after a week or two of treatment, you will feel a lot better, and if you have infectious TB you will stop being able to pass on the disease to others as long as you take anti-TB medication.
However, it is vital to go on and complete the full course of anti-TB treatment. Failure to do this can cause the TB to come back, or drug resistance to emerge. If you would like more information on why taking medicines properly is important and some tips on how you can improve your chances of taking your medicines properly read the booklet in this series called Adherence.
Directly observed therapy
Because of concerns about drug-resistant TB, it might be recommended that a healthcare worker visits you at home every day to make sure that you take your medication. This is called Directly Observed Therapy (DOT for short), and although it is standard practice in some countries, it is only used in exceptional circumstances in the UK, one of which is multi-drug resistant TB (see page xx).
Treat TB first or TB and HIV together?
There are potential interactions between some protease inhibitors and non-nucleoside analogue reverse transcriptase inhibitors (NNRTIs) and rifampicin, a key drug included in many anti-TB combinations.
Because of this, many doctors recommend either delaying HIV treatment until the TB has been controlled, or even stopping or changing anti-HIV medication if a person develops TB whilst taking it.
If you have a low CD4 cell count, and start anti-HIV drugs immediately after finishing your TB treatment, you may be at risk of developing what is called immune restoration syndrome. This is when your strengthening immune system is stimulated to attack TB again. This can make you very unwell and cause unpleasant symptoms, particularly fever and an enlargement of the lymph nodes.
The British HIV Association (BHIVA), the professional body for doctors who care for people with HIV, recommends that TB should be treated first if your CD4 cell count is above 200.
If your CD4 cell count is between 100 and 200, then BHIVA recommends that you start your HIV drugs two months after starting your TB drugs. If you have a very weak immune system, with a CD4 cell count below 100, BHIVA recommends that you start anti-HIV treatment as soon as possible after starting TB drugs. Some doctors recommend waiting up to two months to limit the risks of side-effects, drug interactions, and the occurrence of immune reconstitution syndrome.
TB treatment for HIV-positive women who are pregnant
UK doctors make special recommendations for the treatment of TB in HIV-positive pregnant or breastfeeding women.
Because of the risk of TB to the developing baby, it is important that pregnant women with active TB take anti-TB treatment. Women with latent-TB are also recommended to take isoniazid treatment if it is thought that they have a reasonable risk of becoming ill with TB.
TB treatment in pregnant women should consist of four drugs – rifampicin, isoniazid, pyrazinamide and ethambutol for the first two months and then two drugs – rifampicin and isoniazid for a further seven months. Pyridoxine (vitamin B-6) should also be taken to prevent isoniazid causing nerve damage.
Pregnant women are also recommended to take anti-HIV treatment to prevent mother-to-child transmission of HIV. The exact type of treatment will depend on the health of the mother and the stage during pregnancy when HIV was diagnosed. An additional factor for women with TB is the risk of an interaction between some anti-TB drugs and some anti-HIV medicines. Because of this it is extremely important that doctors providing ante-natal care and TB treatment are very knowledgeable about HIV and TB and work very closely together.
Because of the risk of mother-to-child transmission, HIV-positive women in the UK should never breastfeed.
For more information on HIV and pregnancy and mother-to-child transmission of HIV see the booklets in this series, HIV and women and HIV and children.
Interactions between TB drugs and anti-HIV drugs
Many anti-HIV drugs and TB drugs can work well and safely together. However, as mentioned above, there can be interactions. It is not recommended to use certain anti-TB and HIV drugs together or adjust the dose of either the TB or HIV drug.
Rifampicin can cause large reductions in the amount of protease inhibitors in the blood, even if they are “boosted” by ritonavir, making them ineffective and increasing the chance that resistance to anti-HIV drugs will develop. Because of this, rifampicin should not be used with many of the protease inhibitors and NNRTI drugs.
Rifabutin can interact with protease inhibitors and NNRTIs, causing the amount of antiretrovirals in the bloodstream to fall and the amount of rifabutin to increase.
Because of these interactions it is very important that your doctor is skilled in the treatment of both TB and HIV.
TB drugs and anti-HIV drugs - side-effects
Hepatitis (inflammation of the liver) has also been seen in a numbers of people taking HAART who are also taking isoniazid or rifampicin. Isoniazid can also cause painful nerve damage called peripheral neuropathy, and it is recommended that it is used with extreme caution if given at the same time as d4T or ddI which also cause this side-effect. Taking a daily dose of vitamin B-6 (pyridoxine) can help prevent isonaizid causing peripheral neuropathy, but does not prevent peripheral neuropathy caused by anti-HIV drugs.
There can be other complex interactions between anti-TB and anti-HIV drugs. This is another reason why your doctor should be experienced at treating both HIV and TB.