Friday, May 25, 2007

Why They Are Used

Why They Are Used

A person diagnosed as having tuberculosis is likely to be treated with three or four anti-tubercular drugs. This helps to overcome the risk of drug-resistant strains of the bacilli emerging.

The standard drug combination for the treatment of tuberculosis consists of four drugs, usually including Rifampicin, Isoniazid, Pyrazinamide and Ethambutol. Other drugs may be substituted if the initial treatment fails or if drug sensitivity tests indicate that the bacilli are resistant to these drugs.

The standard duration of treatment for a newly diagnosed tuberculosis infection is a six month regimen as follows: Isoniazid, Rifampicin, Pyrazinamide and Ethambutol daily for two months, followed by Isoniazid and Rifampicin for four months. The duration of treatment can be extended from nine months to upto two years in older children at particular risk, such as those whose immune system has been suppressed. Ethambutol can sometimes be omitted if resistance is unlikely. Corticosteroids may be added to the treatment, if the immune system is not supressed, to reduce the amount of tissue damage; and Pyridoxine is also often prescribed to protect the nerves from damage by Isoniazid.

Both the number of drugs required and the long duration of treatment may make treatment difficult, particularly for those who are homeless. To help with this problem supervised administration of treatment is available when required, both in the community dispensary and in the hospital.

Tuberculosis infection in patients with HIV infection or AIDS is treated with the standard anti-tubercular drug regimen; but lifelong preventative treatment with Isoniazid may be necessary.

How They Work

Anti-tubercular drugs act in the same way as antibiotics, either by killing bacilli or preventing them from multiplying.

How They Affect You

Although the drugs start to combat the disease within days, the benefits of drug treatment are usually not noticeable for a few weeks. As the infection is eradicated, the body repairs the damage caused by the disease. Symptoms such as fever and coughing gradually subside and the appetite and general health improve.

Risks And Special Precautions

Anti-tubercular drugs may cause adverse effects (nausea, vomiting, and abdominal pain) and they occasionally lead to serious allergic reactions. When this happens, another drug is substituted.

Rifampicin and Isoniazid may adversely affect the nerves as well. Ethambutol can cause changes in colour vision. Dosage is carefully monitored, especially in children, the elderly and those with reduced kidney function.

Tuberculosis Prevention

A vaccine prepared from an artificially weakened strain of cattle tuberculosis bacteria can provide immunity from tuberculosis by provoking the development of natural resistance to the disease (see Vaccines and immunisation). The BCG (Bacille Calmette-Guerin) vaccine is a form of tuberculosis bacillus that provokes the body's immune response but does not cause the illness because it does not invade tissues. The vaccine is usually given to children between the ages of 10 and 14 years who are shown to have no natural immunity when given a skin test. BCG vaccination may be given to new born babies if, for example, someone in the family has tuberculosis.

The vaccine is usually injected into the upper arm. A small pustule usually, appears 6-12 weeks later, by which time the person can be considered immune.

Common Drugs

Capreomycin, Cycloserine, Ethambutol and Isoniazid, Pyrazinamide, Rifampicin, Refabutin, Streptomycin.


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