Interaction between warfarin and short-term intravenous amiodarone in intensive care unit patients after cardiac surgery

Abstract Background Amiodarone and warfarin are sometimes administered immediately after cardiac surgery. Although the interaction between long-term oral amiodarone and warfarin has been reported, the interaction between warfarin and short-term intravenous amiodarone has not been reported. In this study, we investigated the effect of short-term intravenous amiodarone on the anticoagulant effect of warfarin in patients who underwent cardiac surgery. Methods We retrospectively reviewed the medical records of 11 patients who received oral warfarin before and after cardiac surgery, and loading doses of 125–150 mg or a 750 mg continuous infusion of amiodarone, or both in the intensive care unit (ICU) within 5 days after the surgery between July 2011 and January 2017. The prothrombin time-international normalized ratio (PT-INR)/daily warfarin dose (PT-INR/dose) was used as an indicator of anticoagulant effect. The values before surgery were considered as the baseline. Results The PT-INR and PT-INR/dose values were elevated in 7 and 10 patients, respectively, after amiodarone administration. The mean PT-INR values were not significantly different before and after amiodarone administration (2.13 ± 0.58 vs 2.29 ± 0.50, respectively, p = 0.643). In contrast, the mean PT-INR/dose values were significantly elevated after the administration of amiodarone (0.93 ± 0.46 vs 1.54 ± 0.63, respectively, p = 0.002). Conclusions Short-term intravenous amiodarone enhanced the anticoagulant effect of warfarin in patients admitted to the ICU after cardiac surgery. We suggest that the dose of warfarin should be carefully adjusted for a few days after cardiac surgery if intravenous amiodarone is coadministered

Evaluation of pharmaceutical intervention in direct-acting antiviral agents for hepatitis C virus infected patients in an ambulatory setting: a retrospective analysis

Abstract Background Direct-acting antivirals (DAAs) are known to improve tolerability and have higher efficacy and shorter treatment durations compared with conventional interferon (IFN)-based treatments for hepatitis C virus (HCV) infection. Management of drug interactions and maintenance of patient adherence are important to achieve adequate therapeutic effects, sustained virological response (SVR). In order to maximize the benefits of oral DAA therapy, we established an ambulatory care pharmacy practice, a model of integrated collaboration between physicians and pharmacists, for patients receiving IFN-free DAA therapy. In this study, we evaluated pharmaceutical intervention for patients visiting the ambulatory care pharmacy practice. Methods HCV-infected outpatients who visited our ambulatory care pharmacy practice between September 2014 and May 2017 were eligible for inclusion in the study. When IFN-free DAAs were first prescribed, the physicians recommended all patients to visit the ambulatory care pharmacy practice after their clinical examination. Subsequently, at the second visit or later, the patients visited the pharmacy service before the physician’s examination. The primary endpoint was SVR, defined as HCV RNA below the lower limit of quantification after the completion of treatment. We also evaluated the adherence rate to DAAs, suggestions to the physicians by the pharmacists, and questions from the patients. All data were obtained retrospectively using an electronic medical record system. Results Among the 401 study subjects, 386 patients completed the IFN-free DAA therapy. A total of 365 patients have reached 12 or 24 weeks after completing the treatment. The overall SVR rate was 98.1% (358/365). The proportion of patients with adherence ≥90% was 99.3% (398/401). Two-hundred and sixty-seven (84%) among 318 suggestions of prescription made by the pharmacists mainly to manage the adverse events were accepted by the physicians. The pharmacists received and answered 1072 questions on DAA therapy from the patients. Conclusions This study indicates that the pharmaceutical intervention may contribute to enhanced adherence to DAAs and higher SVR rates in comparison with previous reports. This study also demonstrates that collaboration between physicians and pharmacists in an ambulatory setting provides favorable outcomes for patients receiving IFN-free DAAs