Subtherapeutic INR values associated with a switch to generic warfarin
Subtherapeutic INR values associated with a switch to generic warfarin
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DOI：
10.1345/aph.10207
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发表时间：
2001-02-01
影响因子：
2.9
通讯作者：
Havrda, DE
中科院分区：
文献类型：
--
作者：
Hope, KA;Havrda, DE
目的：讨论患者从香豆素治疗转为仿制药华法林时对国际标准化比值 (INR) 的影响。 病例摘要：俄克拉荷马城家庭医学中心抗凝诊所的两例病例，其中从香豆素治疗转为仿制药华法林后 INR 值出现亚治疗，而所有其他变量保持一致，这表明当患者在不同品牌的华法林之间转换时需要密切监测 INR。 讨论：华法林是一种治疗指数窄的药物，因为全身浓度的微小变化可能导致药效学反应的显着变化。 1997年3月，美国食品药品监督管理局（FDA）根据FDA和美国药典（USP）标准批准了华法林仿制药。由于杜邦制药和 USP 之间的规格不同，华法林的品牌和仿制药的含量均匀度可能有所不同。有限的研究证明了品牌和仿制药之间的生物等效性。所提供的两个案例表明，在仿制药和品牌药之间切换时，INR 可能会出现波动。因此，这些案例表明，如果发生变化，需要密切监测。 结论：虽然 FDA 认为香豆素和仿制药华法林之间具有生物等效性，但在香豆素和仿制药华法林之间切换可能会导致 INR 发生显着变化，由于杜邦制药和 USP 之间的含量均匀性规格不同，因此需要调整剂量。在香豆素和仿制药华法林之间转换的患者应更仔细地监测其 INR。
OBJECTIVE: To discuss the effect on the international normalized ratio (INR) when patients are converted from therapy with Coumadin to generic warfarin.CASE SUMMARY: Two cases at a family medicine center anticoagulation clinic in Oklahoma City, OK, in which subtherapeutic INR values occurred after a switch from Coumadin to generic warfarin, while all other variables were kept consistent demonstrate the for close monitoring of the INR when patients are switched between brands of warfarin.DISCUSSION: Warfarin is a narrow therapeutic index drug since small changes in systemic concentration can lead to significant variation in pharmacodynamic response. In March 1997, the Food and Drug Administration (FDA) approved generic warfarin based on the FDA and United States Pharmacopeia (USP) standards. Due to different specifications between Dupont Pharma and the USP content uniformity may differ between brand and generic forms of warfarin. Limited studies have demonstrated bioequivalence between brand and generic. The two cases presented demonstrate the potential for fluctuations in the INR when switching between generic and brand. Thus, these cases illustrate the need for close monitoring if a change is made.CONCLUSIONS: While considered bioequivalent by the FDA, switching between Coumadin and generic warfarin may lead to significant changes in the INR, warranting dose alterations due to different content uniformity specifications between Dupont Pharma and the USP. Patients switching between Coumadin and generic warfarin should have their INR monitored more carefully.