Practical information on using rifamycins

The rifamycins include rifampicin, rifabutin, rifaximin and rifapentine.

Rifampicin and rifabutin are active against gram-positive bacteria (including staphylococci), gram-negative bacteria and mycobacteria. These drugs must always be used in combination with antimicrobials from a different class because of the rapid emergence of resistance.

Rifabutin is used for the treatment and prophylaxis of Mycobacterium avium complex (MAC) infection.

Rifampicin is mainly used for the treatment of tuberculosis, nontuberculous mycobacteria (including MAC) and methicillin-resistant Staphylococcus aureus (MRSA) infection. Rifampicin is also used as prophylaxis in contacts of patients with Haemophilus influenzae type b infection and meningococcal disease.

Rifaximin is not systemically absorbed, so is concentrated in the faeces. Rifaximin is active against gram-positive and gram-negative aerobic and anaerobic bacteria. It is mainly used for hepatic encephalopathy. The potential benefits of rifaximin must be balanced against the potential adverse effects, including the development of resistant bacteria.

Rifampicin can cause hepatitis; measure liver biochemistry before starting and during treatment. Warn patients that rifamycins can cause orange discolouration of bodily fluids, including urine, sweat and tears, and that soft contact lenses can become stained.

Rifampicin and rifabutin have many clinically significant drug interactions. Consult an appropriate resource on drug interactions if starting or stopping these drugs in patients taking other drugs.