Treating tuberculosis

Rifampicin and isoniazid (INH) are the two key drugs used in treating tuberculosis (TB), and are not used much outside of this indication.

Rifampicin inhibits protein synthesis by inhibiting the formation of RNA (RNA is the molecule which “tells” the ribosome which protein to make). INH acts by inhibiting the synthesis of various components of the mycobacterial cell wall (which is different in structure to both Gram positive and Gram negative cell walls). Both of these drugs can be given orally or intravenously.

Rifampicin has a fairly broad spectrum of activity, including both Gram positive and Gram negative organisms. Resistance to this agent often develops in bacteria if rifampicin is used on its own. In treating TB it is always used in combination with other drugs. Other possible uses (as part of a combination) include:

• Therapy of infective endocarditis on artificial heart valves
• Legionnaire’s disease
• Brucellosis

Isoniazid is only used for the treatment of TB, and has no notable activity against other organisms.

The main side effect of both of these drugs is toxicity of the liver, and although this is very uncommon, it can be severe.

For more information on care and support of tuberculosis visit South African National TB Association (SANTA) or phone them on 011 454 0260.

December 2001