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 rifampin and 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.
Rifampin is contraindicated in patients with a history of hypersensitivity to any of the rifamycins.(See WARNINGS.)
Rifampin 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If signs of hepatocellular damage occur, rifampin should be withdrawn.In some cases, hyperbilirubinemia resulting from competition between rifampin and bilirubin for excretory pathways of the liver at the cell level can occur in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.
The possibility of rapid emergence of resistant meningococci restricts the use of rifampin to short-term treatment of the asymptomatic carrier state.Rifampin is not to be used for the treatment of meningococcal disease.