18.02.4 Rifampicin

Rifampicin is one of the most important drugs in the treatment of tuberculosis.  Rifampicin acts to inhibit RNA synthesis in the Mycobacterium.  Importantly, this makes rifampicin bactericidal and effective against dormant cells.  As the most difficult thing to overcome in TB is the slow growth and presence of dormant cells, this makes rifampicin a very useful drug.  Rifampicin is the most important drug in the sterilising phase of treatment, the second phase of TB treatment, where the objective is to kill the dormant bacteria

Rifampicin has few serious adverse effects.  One problem with rifampicin is that it induces liver enzymes, particularly CYP450 enzymes involved in drug metabolism.  This can lead to a decrease in the levels, and therefore the effectiveness of these drugs (e.g. oral contraceptives).

The combination of isoniazid and rifampicin is very useful as it gives both bactericidal and sterilising effects.