Rifampicin

What is rifampicin?

Rifampicin is an antibiotic used to treat serious bacterial infections. It may be prescribed by dermatologists for the treatment of:

• Recurrent boils
• Folliculitis decalvans
• Hidradenitis suppurativa
• Tuberculosis
• Leprosy.

What infections does rifampicin treat?

It is also used to treat brucellosis, for serious staphylococcal infections, and to clear asymptomatic carriers of Neisseria meningiditis (which can cause meningococcal disease).

Rifampicin is active against a variety of organisms including Staphylococcus aureus, coagulase negative staphylococcus, Mycobacterium tuberculosis, Mycobacterium leprae, Neisseria meningiditis and Brucella species.

How is rifampicin prescribed?

In New Zealand rifampicin is available as:

• Rifadin™ tablets, suspension and intravenous infusion
• Rifinah™ tablets, where it is combined with isoniazid for the treatment of tuberculosis and leprosy

Rifampicin is often prescribed with another antibiotic in order to prevent bacterial resistance, which can develop rapidly if it is used alone.

It should be taken on an empty stomach at least 30 minutes before a meal or 2 hours after a meal. Antacids should be given at least 1 hour after rifampicin.

What are the side effects of rifampicin?

Rifampicin is usually well-tolerated and rarely causes serious toxicity. The commonest side effects involve the skin and the gastrointestinal system.

Discoloured urine on rifampicin

Effects of bodily fluids

Tears, sweat and urine may become orange coloured by oral rifampicin. Contact lenses may be permanently stained. This effect is usually mild and self-limiting.

Cutaneous adverse reactions

Rifampicin may cause flushing and itching, with or without rash. Other cutaneous reactions reported are:

• Drug-induced urticaria
• Erythema multiforme
• Toxic epidermal necrolysis (rare).

Gastrointestinal effects

Rifampicin may cause loss of appetite, vomiting, abdominal pain and diarrhoea.

Liver disease

Hepatitis can be caused by rifampicin, particularly if rifampicin is given with isoniazid.

Blood disorders

Serious haematological disorders have been reported in patients taking rifampicin, including:

• Thrombocytopenia (low platelet count), which may potentially result in bruising and bleeding
• Low white blood cell count; very rarely, agranulocytosis (severely decreased white blood cell counts)
• Disseminated intravascular coagulation (also very rare).

Musculoskeletal

Muscle weakness and myopathy are uncommon side effects of rifampicin.

Other

Rifampicin is sometimes used intermittently (less than 2 to 3 doses per week) for the treatment of tuberculosis and leprosy. When rifampicin is used in this way, it may be associated with a ‘flu-like syndrome, shortness of breath, low blood pressure, acute renal failure and shock.

Drug interactions with rifampicin

Rifampicin is a P-glycoprotein inducer and may increase the breakdown of other medications, making them less effective. The dosage of these drugs may need adjustment if they are taken together with rifampicin:

• Anticoagulants (warfarin, dabigatran)
• Anticonvulsants (phenytoin)
• Antiarrhythmics (disopyramide, mexiletine)
• Antipsychotics (eg, haloperidol)
• Antifungals (eg, itraconazole)
• Antiretroviral drugs (eg, zidovudine)
• Beta-blockers
• Calcium channel blockers (eg, diltiazem, verapamil)
• Chloramphenicol
• Clarithromycin
• Corticosteroids
• Ciclosporin
• Dapsone
• Digoxin
• Hormonal contraceptives  
• Benzodiazepines (eg, diazepam).

Precautions that should be taken when on rifampicin

• Non-hormonal contraceptive methods may be necessary for women of childbearing age when taking rifampicin, due to its effects on oral contraceptives, injected contraceptives, and implanted contraceptives.
• If used in pregnancy, rifampicin may be harmful to the fetus without causing malformations. It appears in breast milk.
• Baseline blood tests should be done in adults, including a blood count, renal function tests, and liver function tests. If there are significant abnormalities, these should be repeated during treatment. Caution should be taken when there is a pre-existing liver disease or liver function abnormalities.