Effect of rifampicin on anticoagulation of warfarin: A case report

Table 2 Summary of studies reporting interaction of rifampin and warfarin

Ref.	Country	Race	Age in yr	Sex	Therapeutic INR range	Disease	Warfarin dose range in mg/d	Warfarin dose adjustment
Romankiewicz et al[8], 1975	United States	Black	48	Male	Prothrombin time	Tuberculosis, pulmonary embolism	7.5-20	Starting dose of 7.5 mg/d, increased to 20 mg/d within 8 d, and warfarin dose decreased by 50% 7 d after rifampicin was discontinued
Self et al[25], 1975	United States	Unknown	72	Male	Prothrombin time	Pulmonary tuberculosis, pulmonary embolism	5-20	Initially 5 mg/d, increased to 20 mg/d, decreased to 15 mg/d after 8 d of rifampicin discontinuation, and gradually decreased to 10 mg/d
Almog et al[26], 1988	Israel	White	30	Female	Prothrombin time	Chronic obstructive lung disease, pulmonary tuberculosis, deep vein thrombosis, pulmonary embolism	8.7-15.3	Average 15.3 mg/d to attain therapeutic INR and decreased by 50% to average 8.7 mg/d after rifampicin discontinued
Casner et al[27], 1996	United States	Black	36	Male	2.0-3.0	Staphylococcus aureus infection, pulmonary embolism	5-20	10 mg/d, increased to 20 mg/d in 20 d, decreased to 5 mg/d immediately after rifampin is stopped
Lee et al[22], 2001	United States	Unknown	58	Female	2.0-3.0	Pulmonary tuberculosis, left ventricular dysfunction	5-25	Starting at 5 mg/d, increased by 233% over 4 mo and unable to attain therapeutic INR during rifampicin combination. A gradual 70% reduction in warfarin dose over 4-5 wk after rifampicin discontinued
Baciewicz et al[9], 2013	United States	Unknown	79	Male	2.0-3.0	Deep vein thrombosis, pulmonary embolism, osteomyelitis	5-25	Taking long-term warfarin at 5 mg/d, the dose increased by 10%-25% weekly to 25 mg/d after combined use. The dose was reduced by 70% within 4-5 wk to 5 mg/d after rifampicin discontinued
Unal et al[28], 2007	Turkey	Unknown	16	Female	2.0-3.0	Drug abuse	—	Acute event, not comparable
Krajewski et al[18], 2010	United States	White	71	Male	2.0-3.0	Deep vein thrombosis, prosthetic knee infection due to methicillin-resistant Staphylococcus aureus	5-25	Starting at 5 mg/d, increased to 25 mg/d in 2 mo, and the 5-fold increase did not reach the therapeutic INR. After stopping rifampicin, it was reduced by 30% to 17.5 mg/d, and after 3 d it was reduced by 20% to 12.5 mg/d, reduced to 10 mg/d after 1 wk, then gradually reduced to 5-5.5 mg/d in the next 2-3 mo
Martins et al[19], 2013	Brazil	Non-white	59	Female	2.0-3.0	Atrial fibrillation, pleural TB	5.3-11	Long-term use of 7.5 mg/d, increased to 11 mg/d within 3 mo after combined use, hematuria occurred after rifampicin was discontinued, the drug was stopped twice, the dose decreased by 33% to 7.5 mg/d, and then adjusted to 5.3 mg/d
Fahmi et al[20], 2016	Sri Lanka	White	34	Female	2.5-3.5	Mitral valve replacement, infective endocarditis	7.5-30	7.5 mg/d, conservatively increased to 15 mg/d in 1 mo, 22 mg/d in 2 wk, and then increased to 30 mg/d. Continuous monitoring of INR value after antibiotics discontinued without dose adjustment. At 11 d of discontinuation, the INR value increased to 10.2, then dose reduced to 7.5 mg/d
Raru et al[29], 2019	United States	White	67	Male	2.0-3.0	Pulmonary vein thrombosis, tuberculosis	-	10 mg/d

INR: International normalized ratio; TB: Tuberculosis.