Complex Interaction of Rifampin and Warfarin

Almog, Shlomo; Martinowitz, Uriel; Halkin, Hillel; Bank, H; Farfel, Zvi

doi:10.1097/00007611-198810000-00024

Cited by 21 publications

(29 citation statements)

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“…As an additional mechanism, an acquired inhibition of fibrin stabilization has been associated with isoniazid therapy [31]. In the present case, the stimulatory effect of rifampicin on the liver seemed to be clinically predominant over the effect of the concomitant use of isoniazid on the coagulation state, which is consistent with previous findings [12,14,15]. …”

Section: Discussionsupporting

confidence: 91%

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

Martins

Reis

Sales

et al. 2013

BMC Pharmacol Toxicol

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BackgroundRifampicin remains one of the first-line drugs used in tuberculosis therapy. This drug´s potential to induce the hepatic cytochrome P450 oxidative enzyme system increases the risk of drug-drug interactions. Thus, although the presence of comorbidities typically necessitates the use of multiple drugs, the co-administration of rifampicin and warfarin may lead to adverse drug events. We report a bleeding episode after termination of the co-administration of rifampicin and warfarin and detail the challenges related to international normalized ratio (INR) monitoring.Case presentationA 59-year-old Brazilian woman chronically treated with warfarin for atrial fibrillation (therapeutic INR range: 2.0-3.0) was referred to a multidisciplinary anticoagulation clinic at a university hospital. She showed anticoagulation resistance at the beginning of rifampicin therapy, as demonstrated by repeated subtherapeutic INR values. Three months of sequential increases in the warfarin dosage were necessary to reach a therapeutic INR, and frequent visits to the anticoagulation clinic were needed to educate the patient about her pharmacotherapy and to perform the warfarin dosage adjustments. The warfarin dosage also had to be doubled at the beginning of rifampicin therapy. However, four weeks after rifampicin discontinuation, an excessively high INR was observed (7.22), with three-day macroscopic hematuria and the need for an immediate reduction in the warfarin dosage. A therapeutic and stable INR was eventually attained at 50% of the warfarin dosage used by the patient during tuberculosis therapy.ConclusionsThe present case exemplifies the influence of rifampicin therapy on warfarin dosage requirements and the increased risk of bleeding after rifampicin discontinuation. Additionally, this case highlights the need for warfarin weekly monitoring after stopping rifampicin until the maintenance dose of warfarin has decreased to the amount administered before rifampicin use. In particular, patients with cardiovascular diseases and active tuberculosis represent a group with a substantial risk of drug-drug interactions. Learning how to predict and monitor drug-drug interactions may help reduce the incidence of clinically significant adverse drug events.

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Section: Discussionsupporting

confidence: 91%

“…This drug-drug interaction has been described in individual case reports [12-18] and pharmacokinetic studies [19-21]. The effect of the rifampicin-warfarin interaction on the anticoagulant response can be tested using the international normalized ratio (INR), which is the current standard for monitoring warfarin responses.…”

Section: Introductionmentioning

confidence: 99%

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

Martins

Reis

Sales

et al. 2013

BMC Pharmacol Toxicol

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“…Rifampin, however, is a potent inducer of the cytochrome P‐450 enzyme system, which enhances the elimination of certain drugs including warfarin and results in a number of clinically significant drug‐drug interactions 7–9 . Although the warfarin‐rifampin interaction is generally recognized in clinical practice, data supporting this interaction are limited to 6 individual case reports 10–15 and 3 small pharmacokinetic‐pharmacodynamic studies 16–18 …”

Section: Discussionmentioning

confidence: 99%

Update on the Interaction of Rifampin and Warfarin

Kim

Epplen

Foruhari

et al. 2007

Progress Cardiovascular Nurs

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A 79-year-old man with a history of deep vein thrombosis and pulmonary embolism received anticoagulation therapy with warfarin 5 mg daily for 8 months. He was diagnosed with osteomyelitis and underwent partial metatarsal resection of his right foot. After surgery, antibiotics were initiated, including ertapenem sodium 1 g intravenously every 24 hours, vancomycin 1400 mg intravenously every 24 hours, and rifampin 300 mg by mouth twice daily. Achieving a therapeutic level of anticoagulation was difficult despite escalating doses of warfarin, because of the interaction with rifampin. A 5- to 6-fold increase in warfarin dose was prescribed to reach therapeutic international normalized ratios (INRs), but even these increases were insufficient to maintain his INR in the therapeutic range. After rifampin was discontinued, warfarin doses were gradually reduced over the next 2 months. When concurrent warfarin-rifampin therapy is necessary, vigilant monitoring is imperative and significant increases in warfarin doses are likely.

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“…During the course of treatment the complex interaction of anti tubercular drug with warfarin should be kept in mind. Rifampicin is known to reduce the effect of warfarin on pro-thrombin activity (15,16) .…”

Section: Introductionmentioning

confidence: 99%

IJV Thrombosis in a case of Tubercular Cervical Lymphadenopathy

Mittal¹

2018

jmscr

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Complex Interaction of Rifampin and Warfarin

Cited by 21 publications

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

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

Update on the Interaction of Rifampin and Warfarin

IJV Thrombosis in a case of Tubercular Cervical Lymphadenopathy

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