Lee C R, Thrasher K A
Division of Pharmacotherapy, School of Pharmacy, University of North Carolina at Chapel Hill, USA.
Pharmacotherapy. 2001 Oct;21(10):1240-6. doi: 10.1592/phco.21.15.1240.33897.
The clinical significance of rifampin's induction of warfarin metabolism is well documented, but no published studies or case reports have quantified this interaction with respect to the international normalized ratio (INR). A patient receiving concomitant rifampin and warfarin to treat a mycobacterial infection and intraventricular thrombus, respectively, underwent routine INR testing at a pharmacist-managed anticoagulation clinic to assess his anticoagulation regimen. A 233% increase in warfarin dosage over 4 months proved insufficient to attain a therapeutic INR during long-term rifampin therapy More aggressive titration of the warfarin dosage was needed. In addition, a gradual 70% reduction in warfarin dosage over 4-5 weeks was necessary to maintain a therapeutic INR after rifampin discontinuation, demonstrating the clinically significant offset of this drug interaction. Extensive changes in warfarin dosage are required to attain and maintain a therapeutic INR during the initiation, maintenance, and discontinuation of rifampin.
利福平诱导华法林代谢的临床意义已有充分文献记载，但尚无已发表的研究或病例报告对这种相互作用相对于国际标准化比值（INR）进行量化。一名分别接受利福平和华法林治疗分枝杆菌感染和脑室内血栓的患者，在一家由药剂师管理的抗凝门诊接受了常规INR检测，以评估其抗凝方案。在长期利福平治疗期间，4个月内将华法林剂量增加233%仍不足以达到治疗性INR，需要更积极地调整华法林剂量。此外，在停用利福平后，有必要在4至5周内将华法林剂量逐渐减少70%，以维持治疗性INR，这表明这种药物相互作用具有临床上显著的抵消作用。在利福平开始使用、维持使用和停用期间，需要大幅调整华法林剂量才能达到并维持治疗性INR。
