Description

In the treatment of both tuberculosis and the meningococcal carrier state, the small number of resistant cells present within large populations of susceptible cells can rapidly become the predominant type. Bacteriologic cultures should be obtained before the start of therapy to confirm the susceptibility of the organism to rifampinand they should be repeated throughout therapy to monitor the response to treatment. Since resistance can emerge rapidly, susceptibility tests should be performed in the event of persistent positive cultures during the course of treatment. If test results show resistance to rifampin and the patient is not responding to therapy, the drug regimen should be modified.

Should be taken on an empty stomach. Best taken on an empty stomach 1 hr before or 2 hr after meals.

May accelerate the metabolism and reduce the effect of drugs that are metabolised by CYP450 enzymes (e.g. quinidine, phenytoin, theophylline). Decreased concentrations of atovaquone and increased concentrations of rifampicin when taken concomitantly. Concurrent use of ketoconazole and rifampicin may result in decreased serum concentrations of both drugs. May decrease serum concentrations of enalaprilat. Reduced absorption by antacids. Increased risk of hepatotoxicity with halothane or isoniazid.

Rifampicin is contraindicated in patients with a history of hypersensitivity to rifampin or any of the components, or to any of the rifamycins. Rifampin is contraindicated in patients who are also receiving ritonavir-boosted saquinavir due to an increased risk of severe hepatocellular toxicity. Rifampin is contraindicated in patients who are also receiving atazanavir, darunavir, fosamprenavir, saquinavir, or tipranavir due to the potential of rifampin to substantially decrease plasma concentrations of these antiviral drugs, which may result in loss of antiviral efficacy and/or development of viral resistance.

Facial flushing and itching, with or without a rash, flu-like syndrome characterised by episodes of fever, chills, headache, dizziness, bone pain, shortness of breath, and malaise; GI adverse effects (e.g. nausea, vomiting, anorexia, diarrhoea, epigastric distress), pseudomembranous colitis, eosinophilia, leucopenia, haemolytic anaemia; alterations in kidney function and renal failure, menstrual disturbances, oedema, myopathy, muscular weakness; orange-red discolouration of the urine, faeces, sweat, saliva, sputum, tears, and other body fluids; thrombophlebitis, local irritation and inflammation after prolonged IV infusion. Rarely, eye irritation and visual disturbances, anaphylaxis or shock.

Pregnancy: When administered during the last few weeks of pregnancy, rifampin can cause post natal hemorrhages in the mother and infant for which treatment with vitamin K may be indicated. Nursing Mothers: Because of the potential for tumorigenicity shown for rifampin in animal studies, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Rifampicin has been shown to produce liver dysfunction. Fatalities associated with jaundice have occurred in patients with liver disease and in patients taking rifampin with other hepatotoxic agents. Patients with impaired liver function should be given rifampin only in cases of necessity and then with caution and under strict medical supervision. In these patients, careful monitoring of liver function, especially SGPT/ALT and SGOT/AST should be carried out prior to therapy and then every 2 to 4 weeks during therapy. If signs of hepatocellular damage occur, rifampin should be withdrawn. In some cases, hyperbilirubinemia resulting from competition between rifampin and bilirubin for excretory pathways of the liver at the cell level can occur in the early days of treatment. An isolated report showing a moderate rise in bilirubin and/or transaminase level is not in itself an indication for interrupting treatment; rather, the decision should be made after repeating the tests, noting trends in the levels, and considering them in conjunction with the patient's clinical condition. Rifampin has enzyme-inducing properties, including induction of delta amino levulinic acid synthetase. Isolated reports have associated porphyria exacerbation with rifampin administration.