Diffuse Alveolar Hemorrhage Caused by Warfarin after Rifampicin Discontinuation

Oral anticoagulants and concurrent rifampin administration in tuberculosis patients with non-valvular atrial fibrillation

BACKGROUND

Evidence and guidelines for Non-vitamin K antagonist oral anticoagulants (NOACs) use when prescribing concurrent rifampin for tuberculosis treatment in patients with non-valvular atrial fibrillation (NVAF) are limited.

METHODS

Using the Korean National Health Insurance Service database from January 2009 to December 2018, we performed a population-based retrospective cohort study to assess the net adverse clinical events (NACE), a composite of ischemic stroke or systemic embolism and major bleeding, of NOACs compared with warfarin among NVAF patients taking concurrent rifampin administration for tuberculosis treatment. After a propensity matching score (PSM) analysis, Cox proportional hazards regression was performed in matched cohorts to investigate the clinical outcomes.

RESULTS

Of the 735 consecutive patients selected, 465 (63.3%) received warfarin and 270 (36.7%) received NOACs. Among 254 pairs of patients after PSM, the crude incidence rate of NACE was 25.6 in NOAC group and 32.8 per 100 person-years in warfarin group. There was no significant difference between NOAC and warfarin use in NACE (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.48-1.14; P = 0.172). Major bleeding was the main driver of NACE, and NOAC use was associated with a statistically significantly lower risk of major bleeding than that with warfarin use (HR, 0.63; 95% CI, 0.40-1.00; P = 0.0499).

CONCLUSIONS

In our population-based study, there was no statically significant difference in the occurrence of NACE between NOAC and warfarin use. NOAC use may be associated with a lower risk of major bleeding than that with warfarin use.

Genetic Polymorphism Effect on Warfarin-Rifampin Interaction: A Case Report and Review of Literature

Warfarin-rifampin interaction has been reported since the 1970s. Due to rifampin's strong induction of CYP2C9, most cases could not attain the target international normalized ratio (INR) despite warfarin dose escalation. Genetic polymorphisms determine up to 50% of warfarin dose variability. A 38-year-old woman was started on warfarin and rifampin for cerebral venous sinus thrombosis and pulmonary tuberculosis. Over six weeks, the daily warfarin dose was increased from 3 to 10 mg to attain three consecutive in-clinic therapeutic INRs. She completed three complications-free months of warfarin treatment with time in therapeutic range (TTR) of 46%. We performed retrospective genetic testing to determine the patient's CYP2C9, CYP4F2, and VKORC1 genotypes and whether they had affected the interaction outcome. The analysis revealed that the subject carries CYP2C9*3*3 and VKORC1-1639 (GA) mutations, classifying her as a slow metabolizer and, hence, highly warfarin-sensitive. This was reflected on how the case responded to a relatively lower dose than previously reported cases that did not achieve the target on warfarin daily doses up to 35 mg. This is the first report addressing the genotype effect on this interaction. Patients with genetic variants requiring low warfarin doses are more likely to respond at a feasible dose while on rifampin. Future studies to evaluate warfarin-rifampin-gene interaction are warranted.

Strategies and Advances in Combating COVID-19 in China

Coronavirus disease 2019 (COVID-19)-the third in a series of coronavirus infections-has caused a global public health event in the 21st century, resulting in substantial global morbidity and mortality. Building on its legacy of managing severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), China has played a key role in the scientific community by revealing the viral transmission routes and clinical characteristics of COVID-19 and developing novel therapeutic interventions and vaccines. Despite these rapid scientific and technological advances, uncertainties remain in tracing the original sources of infection, determining the routes of transmission and pathogenesis, and addressing the lack of targeted clinical management of COVID-19. Here, we summarize the major COVID-19 research advances in China in order to provide useful information for global pandemic control.

A rare case of Diffuse Alveolar Hemorrhage (DAH) due to warfarin toxicity

INTRODUCTION

Warfarin is one of the most frequently used anticoagulant agents in the clinic. The most important adverse effect of warfarin is hemorrhage of vital organs, such as lung and brain. Diffuse Alveolar Hemorrhage (DAH) is a rare clinical condition which occurs due to variety of medical disorders. Although it's rarely reported, DAH can be a result of coagulopathy prompted by warfarin therapy. In this study we present a case of DAH, caused by warfarin toxicity which referred to the hospital with non-specific respiratory symptoms.

CASE PRESENTATION

A 41-year-old female patient referred to the hospital complaining of shortness of breath, cough and dizziness. She had been taking warfarin due to mitral valve replacement for the past 10 years. Her recent symptoms began shortly after taking amoxicillin, a few days before admission. Early clinical examination and paraclinical studies reveal DAH as the cause of respiratory symptoms. The patient was then intubated and received fresh frozen plasma, packed cells and oral vitamin K. Laboratory findings apart from increased INR, PT, ESR and CRP were all within normal range. After the initiation of treatment patient's INR decreased and her clinical condition improved. Follow-up CT-Scan and bronchoscopy also confirmed resolving DAH.

CONCLUSIONS

The usage of warfarin in anticoagulation should be closely monitored due to its narrow therapeutic window and other factors, including its interaction with other medications such as antibiotics. Warfarin toxicity can lead to DAH, a life-threatening condition which can be presented with non-specific symptoms and deteriorate patient's clinical condition in a short time. Therefore, it is of utmost importance to watch closely for primary symptoms of such rare incident in patients under warfarin therapy and initiate treatment as soon as possible, to prevent mortality.