QUINIDINE AND RIFAMPICIN (RIFAMPIN)
The serum levels of quinidine and its therapeutic effects can be markedly reduced by rifampicin. In one case quinidine levels were reduced from 4 to 0.5 micrograms/mL.
The dosage of quinidine will need to be increased (possibly more than doubled in some patients) if rifampicin is given concurrently. The quinidine dose will need to be reduced when the rifampicin is stopped. Monitor the serum levels where possible.
The dosage of quinidine will need to be increased (possibly more than doubled in some patients) if rifampicin is given concurrently. The quinidine dose will need to be reduced when the rifampicin is stopped. Monitor the serum levels where possible.