Retrospective evaluation of a possible interaction between warfarin and levofloxacin
Retrospective evaluation of a possible interaction between warfarin and levofloxacin
复制标题
DOI：
10.1592/phco.25.1.67.55624
复制
发表时间：
2005-01-01
期刊：
影响因子：
4.1
通讯作者：
Anderson, HG
中科院分区：
文献类型：
--
作者：
McCall, KL;Scott, JC;Anderson, HG
研究目标。为了阐明可疑药物相互作用的临床意义，我们试图确定在接受长期华法林治疗的患者中使用左氧氟沙星是否会影响国际标准化比率(INR)。使用药房和医疗记录的回溯性队列研究。门诊病人。43名接受长期华法林治疗的患者随后被开出左氧氟沙星(22名患者)或非洛地平(21名对照)的处方；非洛地平被选择是因为它被证明不与华法林相互作用。两组患者均需在开始使用左氧氟沙星或非洛地平前(Pre-INR)以及在左氧氟沙星或非洛地平治疗期间或开始用药后15天内(Pre-INR)记录INR。两个治疗组之间的患者人口统计学相似。左氧氟沙星组和对照组患者的平均+/-SD年龄分别为59.5±8.7岁和65.3+/-11.5岁(P=0.07)。左氧氟沙星组和非洛地平组治疗前后INR(主要结局指标)的平均变化分别为0.31+/-0.82(INR前2.46，INR后2.76)和0.21+/-0.54(INR前2.46，INR后2.67)(p=0.65)。基于样本得出的加权标准差0.68进行的事后功率分析显示，该研究有66%的功率来检测INR值0.5的变化。左氧氟沙星组有41%(9/22例)患者需要华法林剂量调整，而非洛地平组(7/21例)需要根据治疗后INR调整华法林剂量。虽然我们的初步分析没有检测到华法林和左氧氟沙星的相互作用，但不能排除这种相互作用的可能性，特别是在特殊情况下。当左氧氟沙星与华法林联合应用时，临床医生应密切监测INR值。
Study Objectives. In order to clarify the clinical significance of a suspected drug interaction, we sought to determine if the international normalized ratio (INR) is affected when levofloxacin is administered in patients receiving long-term warfarin therapy.Design. Retrospective cohort study using pharmacy and medical records.Setting. Outpatient clinic.Patients. Forty-three patients receiving long-term warfarin therapy who subsequently were prescribed either levofloxacin (22 patients) or felodipine (21 controls); felodipine was chosen as it has been shown not to interact with warfarin. Patients in both groups were required to have a documented INR before the start of levofloxacin or felodipine (pre-INR) and either during levofloxacin or felodipine therapy or within 15 days after the drug had been started (post-INR).Measurements and Main Results. Patient demographics were similar between the two treatment groups. The mean +/-SD age of the patients in the levofloxacin and control groups was 59.5 +/- 8.7 and 65.3 +/- 11.5 years, respectively (p=0.07). The mean change between the pre- and post-INR (primary outcome measure) was 0.31 +/- 0.82 (pre-INR 2.46, post-INR 2.76) and 0.21 +/- 0.54 (pre-INR 2.46, post-INR 2.67) in the levofloxacin and felodipine groups, respectively (p=0.65). A post hoc power analysis, based on a sample-derived, weighted standard deviation of 0.68, revealed that the study had 66% power to detect a change of 0.5 in the INR value. The percentage of patients who required a warfarin dosage adjustment based on the post-INR (secondary outcome measure) was 41% (9 of 22 patients) in the levofloxacin group and 33% (7 of 21 patients) in the felodipine group.Conclusion. Although our primary analysis did not detect a warfarin-levofloxacin interaction, the potential for such an interaction, especially in idiosyncratic cases, cannot be ruled out. Clinicians should closely monitor INR values when levofloxacin is administered jointly with warfarin.