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Table 1 Summary of recent studies reporting drug-drug interactions involving rifampicin and warfarin in humans

From: Rifampicin-warfarin interaction leading to macroscopic hematuria: a case report and review of the literature

Study Country Type of study Number of patients Sex Age (years) Warfarin administration Comments
Chronic dose Titration Plasma levels
Lee & Thrasher, 2001 [16] USA Case report 1 Male 58 Yes Yes No A 233% increase in the warfarin dose over four months could not attain a therapeutic INR* during the use of rifampicin. A therapeutic INR* was obtained after a 70% reduction in the warfarin dose over four to five weeks after rifampicin discontinuation.
Kim et al., 2007 [18] USA Case report 1 Male 79 Yes Yes No Increases of 500-600% in the warfarin dose were insufficient to maintain an INR* in the therapeutic range. After rifampicin was discontinued, the warfarin dose was gradually reduced over two months to achieve a therapeutic INR*.
Krajewski, 2010 [17] USA Case report 1 Male 71 Yes Yes No The warfarin dose was sequentially increased by up to 500%, from a starting point of 35–40 mg/week to an endpoint of 175 mg/week over two months, with no achievement of a therapeutic INR*. After rifampicin discontinuation, the warfarin dose was gradually reduced to the initial regimen over three to four months to attain a therapeutic INR*.
  1. * INR international normalized ratio.