Drugs used in the treatment of the bacterial infection tuberculosis
Antituberculous drugs are antibiotics used mainly or exclusively to treat tuberculosis, or TB. The initial infection usually develops in the lungs, but may spread to other parts of the body, such as the kidneys, lymph nodes, and sometimes the membranes covering the brain and spinal cord (see Meningitis). Usually, several antituberculous drugs are given together to prevent drug resistance from developing.
How are they used?
If you are diagnosed with TB, the strain of bacteria causing the infection will be tested to determine its sensitivity to specific anti-tuberculous drugs. While you are waiting for the results, which can take up to 2 months, your doctor will prescribe an initial combination of four drugs to be taken orally. The main drugs used are isoniazid, pyrazinamide, ethambutol, and rifampicin. After the initial 2 months, isoniazid and rifampicin are used. Treatment with these drugs is usually continued for 4 months to ensure that the infection is eradicated. In some cases, this treatment may need to be continued for a longer period, depending on the organs affected. For example, treatment may need to continue for 12 months if the infection has led to meningitis.
It is important that you complete the course of drugs as instructed by your doctor. If you fail to do so, the bacteria may not be eradicated and drug-resistant strains may develop, which can then be transmitted to other people.
What are the side effects?
Antituberculous drugs may cause side effects, such as nausea, vomiting, rashes, and abdominal pain. Isoniazid, pyrazinamide, and rifampicin may damage the liver, so you will have liver function tests before treatment. If your liver function is found to be impaired, you will have regular liver function monitoring during treatment. Kidney function will also be checked before treatment; if your kidney function is impaired, a reduced drug dosage will be given. Rifampicin may turn urine and other body secretions red, but this effect is harmless. Isoniazid may affect the nerves, causing numbness or tingling in the hands or feet. Ethambutol may rarely damage the nerves in the eyes, causing vision problems. People taking it are usually advised to have regular vision tests. If you are taking it and develop blurred vision or cannot distinguish colours, see your doctor promptly.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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