Serious bleeding events due to warfarin and antibiotic co-prescription in a cohort of veterans

Deciphering the Intricate Interplay in the Framework of Antibiotic-Drug Interactions: A Narrative Review

Drug interactions are a significant and integral part of the concept of medication-related adverse events, whether referring to potential interactions or those currently observed in real-world conditions. The high global consumption of antibiotics and their pharmacokinetic and pharmacodynamic mechanisms make antibiotic-drug interactions a key element that requires continuous study due to their clinical relevance. In the present work, the current state of knowledge on antibiotic-drug interactions, which are less studied than other drug-drug interactions despite their frequent use in acute settings, has been consolidated and updated. The focus was on the interactions of the commonly used antibiotics in clinical practice, on the characteristics of the geriatric population susceptible to interactions, and on the impact of online drug interaction checkers. Additionally, strategies for optimizing the management of these interactions, including spacing out administrations, monitoring, or avoiding certain combinations, are suggested. Sustained research and careful monitoring are critical for improving antibiotic safety and efficacy, especially in susceptible populations, to enhance precision in managing antibiotic-drug interactions.

Antibiotic-Drug Interactions in the Intensive Care Unit: A Literature Review

Interactions between drugs are a common problem in Intensive Care Unit patients, as they mainly have a critical condition that often demands the administration of multiple drugs simultaneously. Antibiotics are among the most frequently used medications, as infectious diseases are often observed in ICU patients. In this review, the most important antibiotic-drug interactions, based on the pharmacokinetic and pharmacodynamic mechanisms, were gathered together and described. In particular, some of the most important interactions with main groups of antibacterial drugs were observed in patients simultaneously prescribed oral anticoagulants, NSAIDs, loop diuretics, and valproic acid. As a result, the activity of drugs can be increased or decreased, as dosage modification might be necessary. It should be noted that these crucial interactions can help predict and avoid negative consequences, leading to better patient recovery. Moreover, since there are other factors, such as fluid therapy or albumins, which may also modify the effectiveness of antibacterial therapy, it is important for anaesthesiologists to be aware of them.

Risk of bleeding amongst warfarin and direct oral anticoagulant users prescribed immediate antibiotics for respiratory tract infection: Cohort study

PURPOSE

Incidence of bleeding amongst warfarin and direct oral anticoagulant (DOAC) users is greater following a respiratory tract infection (RTI). It is unclear whether immediate antibiotics modify this association. We estimated the risk of bleeding amongst warfarin and DOAC users with RTI by antibiotic treatment.

METHODS

This retrospective cohort study used data from the Clinical Practice Research Datalink (CPRD) GOLD for adults in England prescribed warfarin or a DOAC, who sought primary care for an RTI between 1st January 2011 and 31st December 2019. Outcomes were major bleeding (hospital admission for intracranial or gastrointestinal bleeding), and non-major bleeding (hospital admission or General Practice consult for epistaxis, haemoptysis, or haematuria). Cox models derived hazard ratios (HRs) and 95% confidence intervals (CIs) for each outcome, adjusting for confounders using inverse probability of treatment weighting.

RESULTS

Of 14 817 warfarin and DOAC users consulting for an RTI, 8768 (59%) were prescribed immediate antibiotics and 6049 (41%) were not. Approximately 49% were female, and median age was 76 years. Antibiotics were associated with reduced risk of major bleeding (adjusted HR 0.38, 95% CI 0.25 to 0.58). This was consistent across several sensitivity analyses. Antibiotics were also associated with a reduced risk of non-major bleeding (adjusted HR 0.78, 95% CI 0.61 to 0.99).

CONCLUSIONS

Immediate antibiotics were associated with reduced risk of bleeding amongst warfarin and DOAC users with an RTI. Further work is needed to understand mechanisms and confirm whether a lower threshold for antibiotic use for RTI in this population may be beneficial.

Cardiovascular diseases and the heart-gut cross talk

The purpose of this narrative review is to provide a comprehensive overview of current research on heart-gut cross talk and its implications for cardiovascular disease. To uncover relevant preclinical and clinical research examining heart-gut cross talk, a thorough literature search was undertaken utilising electronic databases. The chosen publications were critically examined, and major findings were synthesised to offer a thorough perspective on the subject. We want to synthesise the most recent study findings, explain the underlying mechanisms, and provide potential treatment techniques. By exploring bidirectional connection between the heart and the gut, we shed light on novel future options for the prevention and treatment of cardiovascular diseases. The heart-gut cross talk is an exciting field of study with implications for cardiovascular disease. Understanding the complex connection between the heart and the gastrointestinal tract may lead to the development of novel therapeutic targets and therapies for the prevention and management of cardiovascular diseases. Future research should concentrate on identifying the specific processes driving this crosstalk as well as assessing the efficacy of therapies targeting the gut microbiota and the gut-brain axis in improving cardiovascular outcomes.

Unveiling the relationship between gut microbiota and heart failure: Recent understandings and insights

Gut microbiota, which comprises a broad range of bacteria inhabiting the human intestines, plays a crucial role in establishing a mutually beneficial relationship with the host body. Dysbiosis refers to the perturbations in the composition or functioning of the microbial community, which can result in a shift from a balanced microbiota to an impaired state. This alteration has the potential to contribute to the development of chronic systemic inflammation. Heart failure (HF) is a largely prevalent clinical condition that has been demonstrated to have variations in the gut microbiome, indicating a potential active involvement in the pathogenesis and advancement of the disease. The exploration of the complex interplay between the gut microbiome and HF presents a potential avenue for the discovery of innovative biomarkers, preventive measures, and therapeutic targets. This review aims to investigate the impact of gut bacteria on HF.

Warfarin and Antibiotics: Drug Interactions and Clinical Considerations

Warfarin administration poses a notable challenge in clinical practice due to the increased susceptibility of patients to major bleeding, particularly when co-administered with other medications capable of modulating its metabolic pathways. Among these medications, antibiotics have been recognized as potential agents that can either induce or inhibit cytochrome P450-2C9, thereby impacting the effects of warfarin. A wealth of evidence from numerous studies consistently supports an elevated risk of serious bleeding in patients concurrently receiving antibiotics and warfarin therapy. This narrative review elucidates the intricate interactions between warfarin and various antibiotic classes. Notably, significant increases in the International Normalized Ratio (INR) were observed among warfarin-treated patients receiving penicillin derivatives, fluoroquinolones, TMP-SMX, and macrolides. Conversely, investigations have also demonstrated a reduction in INR levels in patients on warfarin when exposed to rifampin, a potent inducer of cytochrome P-450. Intriguingly, cephalosporin antibiotics and amoxicillin/clavulanate, despite not interfering with the cytochrome P450 system, exhibited a positive association with increased INR values. The findings of this narrative review underscore the importance of diligent monitoring in patients on warfarin requiring concomitant antibiotic therapy, as this surveillance strategy proves pivotal in mitigating the risk of major bleeding complications. Additionally, for patients necessitating cytochrome P450 inhibitors such as penicillin derivatives, fluoroquinolones, TMP-SMX, and macrolides, the consideration of dose reduction in warfarin therapy may confer substantial benefits in reducing the occurrence of major bleeding events. Similarly, patients who are co-administered rifampin alongside warfarin necessitate vigilant monitoring, with a potential need for escalating warfarin doses to counteract the risk of a hypercoagulable state.

The Implication of the Gut Microbiome in Heart Failure

Heart failure is a worldwide health problem with important consequences for the overall wellbeing of affected individuals as well as for the healthcare system. Over recent decades, numerous pieces of evidence have demonstrated that the associated gut microbiota represent an important component of human physiology and metabolic homeostasis, and can affect one's state of health or disease directly, or through their derived metabolites. The recent advances in human microbiome studies shed light on the relationship between the gut microbiota and the cardiovascular system, revealing its contribution to the development of heart failure-associated dysbiosis. HF has been linked to gut dysbiosis, low bacterial diversity, intestinal overgrowth of potentially pathogenic bacteria and a decrease in short chain fatty acids-producing bacteria. An increased intestinal permeability allowing microbial translocation and the passage of bacterial-derived metabolites into the bloodstream is associated with HF progression. A more insightful understanding of the interactions between the human gut microbiome, HF and the associated risk factors is mandatory for optimizing therapeutic strategies based on microbiota modulation and offering individualized treatment. The purpose of this review is to summarize the available data regarding the influence of gut bacterial communities and their derived metabolites on HF, in order to obtain a better understanding of this multi-layered complex relationship.

Drug Interactions Affecting Oral Anticoagulant Use

Oral anticoagulants (OACs) are medications commonly used in patients with atrial fibrillation and other cardiovascular conditions. Both warfarin and direct oral anticoagulants are susceptible to drug-drug interactions (DDIs). DDIs are an important cause of adverse drug reactions and exact a large toll on the health care system. DDI for warfarin mainly involve moderate to strong inhibitors/inducers of cytochrome P450 (CYP) 2C9, which is responsible for the elimination of the more potent S-isomer of warfarin. However, inhibitor/inducers of CYP3A4 and CYP1A2 may also cause DDI with warfarin. Recognition of these precipitating agents along with increased frequency of monitoring when these agents are initiated or discontinued will minimize the impact of warfarin DDI. Direct oral anticoagulants are mainly affected by medications strongly affecting the permeability glycoprotein (P-gp), and to a lesser extent, strong CYP3A4 inhibitors/inducers. Dabigatran and edoxaban are affected by P-gp modulation. Strong inducers of CYP3A4 or P-gp should be avoided in all patients taking direct oral anticoagulant unless previously proven to be otherwise safe. Simultaneous strong CYP3A4 and P-gp inhibitors should be avoided in patients taking apixaban and rivaroxaban. Concomitant antiplatelet/anticoagulant use confers additive risk for bleeding, but their combination is unavoidable in many cases. Minimizing duration of concomitant anticoagulant/antiplatelet therapy as indicated by evidence-based clinical guidelines is the best way to reduce the risk of bleeding.

Quantitation of Diclofenac, Tolbutamide, and Warfarin as Typical CYP2C9 Substrates in Rat Plasma by UPLC-MS/MS and Its Application to Evaluate Linderane-Mediated Herb-Drug Interactions

Linderane (LDR), the main active and distinctive component of L. aggregate, is a mechanism-based inactivator of CYP2C9 in vitro, indicating the occurrence of herb-drug interactions. However, little is known about the changes of the pharmacokinetic properties of the common clinical drugs as CYP2C9 substrates after coadministration with LDR. In this study, a selective and rapid ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for the determination of diclofenac, tolbutamide, and warfarin as CYP2C9 substrates in rat plasma has been developed. Chlorzoxazone was employed as an internal standard (IS), and protein precipitation was used for sample preparation. Chromatographic separation was achieved on a UPLC BEH-C₁₈ (2.1 × 50 mm, 1.7 µm) with 0.1% (v:v) formic acid in water (A) and acetonitrile (B) as the mobile phase with gradient elution. The total run time was only 3.8 min. MS analysis was performed under multiple reaction monitoring (MRM) with electron spray ionization (ESI) operated in the negative mode. The bioanalytical method was validated, and the selectivity, carryover effects, linearity, precision, accuracy, matrix effect, extraction recovery, and stability were acceptable. The validated method was then successfully applied for evaluating the potential pharmacokinetic interactions when LDR was used along with diclofenac, tolbutamide, and warfarin, respectively. Results showed that the C _max of diclofenac in the treated group was 1287.82 ± 454.16 μg/L, which was about 5-fold of that in the control group (P < 0.01). The C _max of tolbutamide in the treated group was 60.70 ± 10.70 mg/L, which was significantly decreased by about 25% when compared with the control group (P < 0.01). The V _d of warfarin in the treated group was obviously increased, which was about 1.4-fold of that in the control group (P < 0.01).

Anesthesia Considerations in Infective Endocarditis

The management of infective endocarditis is complex and inherently requires multidisciplinary cooperation. About half of all patients diagnosed with infective endocarditis will meet the criteria to undergo cardiac surgery, which regularly takes place in urgent or emergency settings. The pathophysiology and clinical presentation of infective endocarditis make it a unique disorder within cardiac surgery that warrants a thorough understanding of specific characteristics in the perioperative period. This includes, among others, echocardiography, coagulation, bleeding management, or treatment of organ dysfunction. In this narrative review article, the authors summarize the current knowledge on infective endocarditis relevant for the clinical anesthesiologist in perioperative management of respective patients. Furthermore, the authors advocate for the anesthesiologist to become a structural member of the endocarditis team.

Respiratory tract infection and risk of bleeding in oral anticoagulant users: self-controlled case series

OBJECTIVE

To estimate the association between untreated, community acquired, respiratory tract infections and bleeding in oral anticoagulant users.

DESIGN

Self-controlled case series.

SETTING

General practices in England contributing data to the Clinical Practice Research Datalink GOLD.

PARTICIPANTS

1208 adult users of warfarin or direct oral anticoagulants with a general practice or hospital admission record of a bleeding event between January 2010 and December 2019, and a general practice record of a consultation for a community acquired respiratory tract infection for which immediate antibiotics were not prescribed (that is, untreated).

MAIN OUTCOME MEASURES

Relative incidence of major bleeding and clinically relevant non-major bleeding in the 0-14 days after an untreated respiratory tract infection, compared to unexposed time periods.

RESULTS

Of 1208 study participants, 58% (n=701) were male, median age at time of first bleed was 79 years (interquartile range 72-85), with a median observation period of 2.4 years (interquartile range 1.3-3.8). 292 major bleeds occurred during unexposed time periods and 41 in the 0-14 days after consultation for a respiratory tract infection. 1003 clinically relevant non-major bleeds occurred during unexposed time periods and 81 in the 0-14 days after consultation for a respiratory tract infection. After adjustment for age, season, and calendar year, the relative incidence of major bleeding (incidence rate ratio 2.68, 95% confidence interval 1.83 to 3.93) and clinically relevant non-major bleeding (2.32, 1.82 to 2.94) increased in the 0-14 days after an untreated respiratory tract infection. Findings were robust to several sensitivity analyses and did not differ by sex or type of oral anticoagulant.

CONCLUSIONS

This study observed a greater than twofold increase in the risk of bleeding during the 0-14 days after an untreated respiratory tract infection. These findings have potential implications for how patients and clinicians manage oral anticoagulant use during an acute intercurrent illness and warrant further investigation into the potential risks and how they might be mitigated.

Can manipulation of gut microbiota really be transformed into an intervention strategy for cardiovascular disease management?

Recent advancement in manipulation techniques of gut microbiota either ex vivo or in situ has broadened its plausible applicability for treating various diseases including cardiovascular disease. Several reports suggested that altering gut microbiota composition is an effective way to deal with issues associated with managing cardiovascular diseases. However, actual translation of gut microbiota manipulation-based techniques into cardiovascular-therapeutic approach is still questionable. This review summarized the evidence on challenges, opportunities, recent development, and future prospects of gut microbiota manipulation for targeting cardiovascular diseases. Initially, issues associated with current cardiovascular diseases treatment strategy, association of gut microbiota with cardiovascular disease, and its influence on cardiovascular drugs were discussed, followed by applicability of gut microbiota manipulation as a cardiovascular disease intervention strategy along with its challenges and future prospects. Despite the fact that the gut microbiota is rugged, interventions like probiotics, prebiotics, synbiotics, fecal microbiota transplantation, fecal virome transplantation, antibiotics, diet changes, and exercises could manipulate it. Advanced techniques like administration of engineered bacteriophages and bacteria could also be employed. Intensive exploration revealed that if sufficiently controlled approach and proper monitoring were applied, gut microbiota could provide a compelling answer for cardiovascular therapy.

Prediction of potential drug interactions between repurposed COVID-19 and antitubercular drugs: an integrational approach of drug information software and computational techniques data

Introduction:

Tuberculosis is a major respiratory disease globally with a higher prevalence in Asian and African countries than rest of the world. With a larger population of tuberculosis patients anticipated to be co-infected with COVID-19 infection, an ongoing pandemic, identifying, preventing and managing drug–drug interactions is inevitable for maximizing patient benefits for the current repurposed COVID-19 and antitubercular drugs.

Methods:

We assessed the potential drug–drug interactions between repurposed COVID-19 drugs and antitubercular drugs using the drug interaction checker of IBM Micromedex®. Extensive computational studies were performed at a molecular level to validate and understand the drug–drug interactions found from the Micromedex drug interaction checker database at a molecular level. The integrated knowledge derived from Micromedex and computational data was collated and curated for predicting potential drug–drug interactions between repurposed COVID-19 and antitubercular drugs.

Results:

A total of 91 potential drug–drug interactions along with their severity and level of documentation were identified from Micromedex between repurposed COVID-19 drugs and antitubercular drugs. We identified 47 pharmacodynamic, 42 pharmacokinetic and 2 unknown DDIs. The majority of our molecular modelling results were in line with drug–drug interaction data obtained from the drug information software. QT prolongation was identified as the most common type of pharmacodynamic drug–drug interaction, whereas drug–drug interactions associated with cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) inhibition and induction were identified as the frequent pharmacokinetic drug–drug interactions. The results suggest antitubercular drugs, particularly rifampin and second-line agents, warrant high alert and monitoring while prescribing with the repurposed COVID-19 drugs.

Conclusion:

Predicting these potential drug–drug interactions, particularly related to CYP3A4, P-gp and the human Ether-à-go-go-Related Gene proteins, could be used in clinical settings for screening and management of drug–drug interactions for delivering safer chemotherapeutic tuberculosis and COVID-19 care. The current study provides an initial propulsion for further well-designed pharmacokinetic-pharmacodynamic-based drug–drug interaction studies.

Plain Language Summary

The risk of polypharmacy and potentially inappropriate drugs in residential care dementia patients: tips from the PharE study

AIMS

The aims of the present study, conducted in two regions of Italy, Calabria and Piedmont, were to assess the use of inappropriate drugs according to the Beers Criteria and to study the possible drug-drug interactions.

METHODS

Data were obtained retrospectively from 972 residential care patients between 2016 and 2018. Mean age was 82.4 ± 8.4 years, with a prevalence of women (64.8%). Activities of daily living, instrumental activities of daily living, Mini-Mental State Examination, Cumulative Illness Rating Scale, Neuropsychiatric Inventory Scale and number and kind of drugs were recorded. A classification of potential inappropriate drugs was made according to the Beers criteria. Data were collected through an Excel file able to gather the main information. In the case of suspected adverse event, Naranjo Scale was applied. The study of possible drug-drug interactions was made by Micromedex 2.0.

RESULTS

Functional and cognitive impairments, comorbidities and number of drugs were assessed. The bivariate relationship between number of drugs and glomerular filtration rate assessed by CKD-EPI showed that the higher was the number of drugs used, the worst was kidney function assessment (p = 0.0001). The most frequent inappropriate drugs were anticholinergic drugs, tricyclics antidepressants, long-half-life benzodiazepines, antipsychotics and proton pump inhibitors.

CONCLUSIONS

These data are very interesting and show the need for an accurate choice of drugs in elderly people and for starting a wise deprescribing procedure.

Drug-drug Interactions with Warfarin: A Systematic Review and Meta-analysis

AIM

The objective of this paper is to systematically review the literature on drug-drug interactions with warfarin, with a focus on patient-important clinical outcomes.

METHODS

MEDLINE, EMBASE, and the International Pharmaceutical Abstract (IPA) databases were searched from January 2004 to August 2019. We included studies describing drug-drug interactions between warfarin and other drugs. Screening and data extraction were conducted independently and in duplicate. We synthesized pooled odds ratios (OR) with 95% confidence intervals (CIs), comparing warfarin plus another medication to warfarin alone. We assessed the risk of bias at the study level and evaluated the overall certainty of evidence using GRADE.

RESULTS

Of 42,013 citations identified, a total of 72 studies reporting on 3,735,775 patients were considered eligible, including 11 randomized clinical trials and 61 observational studies. Increased risk of clinically relevant bleeding when added to warfarin therapy was observed for antiplatelet (AP) regimens (OR=1.74; 95% CI 1.56, 1.94), many antimicrobials (OR=1.63; 95% CI 1.45, 1.83), NSAIDs including COX-2 NSAIDs (OR=1.83; 95% CI 1.29, 2.59), SSRIs (OR=1.62; 95% CI 1.42, 1.85), mirtazapine (OR=1.75; 95% CI 1.30, 2.36), loop diuretics (OR=1.92; 95% CI 1.29, 2.86), and others. We found a protective effect of proton pump inhibitors (PPIs) against warfarin-related gastrointestinal (GI) bleedings (OR=0.69; 95% CI 0.64, 0.73). No significant effect on thromboembolic events or mortality of any drug group used with warfarin was found, including single or dual AP regimens.

CONCLUSIONS

This review found low to moderate certainty evidence supporting the interaction between warfarin and a small group of medications, which result in increased bleeding risk. PPIs are associated with reduced hospitalization for upper GI bleeding for patients taking warfarin. Further studies are required to better understand drug-drug interactions leading to thromboembolic outcomes or death.

Uninterrupted direct oral anticoagulant treatment during acute illness: Impact on clinical outcomes

BACKGROUND

Uninterrupted drug therapy during acute illness is often associated with pharmacokinetic and pharmacodynamic variations. Among warfarin treated patients, these changes are reflected in the INR. However, in the case of direct oral anticoagulants (DOACs), given that routine laboratory monitoring is not recommended, these changes may result in unforeseen thromboembolic or bleeding events.

OBJECTIVES

To determine the rate of thromboembolic (TEE) and bleeding events associated with uninterrupted DOAC compared to warfarin treatment during acute illness.

METHODS

A retrospective cohort study of patients treated with DOACs or warfarin, both at steady state, who were hospitalized for acute illness. Primary outcome was any TEE or major bleeding requiring re-hospitalization within one month from discharge. Secondary outcome was a composite of major bleeding and clinically relevant non-major bleeding (CRNMB) events.

RESULTS

A total of 410 patients continued oral anticoagulant treatment during their hospitalization, of whom 191 (46.6%) were on DOACs and 219 (53.4%) on warfarin, with a total of 18 (4.4%) events. Rates of TEE and major bleeding events did not differ between DOACs and warfarin treated patients (0.9% vs. 0.5% and 0.5% vs. 1%, respectively). Similarly, rate of secondary outcome was comparable between DOACs (4.7%) and warfarin (2.7%, p = 0.29). Sub-analyses demonstrated significantly higher rates among rivaroxaban (10.4%) treated patients compared to warfarin (p = 0.03).

CONCLUSION

Uninterrupted treatment with DOACs during acute illness is not associated with increased risk for re-hospitalizations due to bleeding or thromboembolic events compared to warfarin. Our results suggest a higher bleeding rate among rivaroxaban treated patients at high bleeding risk.

Δ-9-tetrahydrocannabinol dose increase leads to warfarin drug interaction and elevated INR

OBJECTIVE

We have reported a case of a drug-drug interaction (DDI) involving warfarin and Δ-9-tetrahydrocannabinol (THC) that resulted in a supratherapeutic international normalized ratio (INR) level. The purpose of this case report is to highlight the possibility of a pharmacokinetic DDI between THC and warfarin.

CASE SUMMARY

A 67-year-old Caucasian man suffering from chronic pain presented to a dispensary in Buffalo, NY, for a refill of his medical cannabis (MC). The patient asked to speak with the pharmacist, and during their discussion the patient stated that he had a supratherapeutic INR level of 5.2 measured at home with a self-test device. The patient had no evidence of bleeding, and administration of warfarin was held for 2 days before the INR level returned to a normal range. The supratherapeutic level occurred when the patient was self-titrating his dose of THC and scored an 8, or "probable," on the Naranjo Adverse Drug Effect Probability Scale.

PRACTICE IMPLICATIONS

Warfarin and cannabinoids such as THC are both metabolized by cytochrome P450 (CYP) isozymes present in the liver and gastrointestinal tract. In the case described, a dose increase of 7.35 mg THC preceded an INR elevation of 5.2, but did not result in any bleeding. These observations are suggestive of a DDI involving warfarin and THC. Clinicians involved with MC should have adequate knowledge of the drugs that act as substrates, inhibitors, and inducers of CYP enzymes, including the major cannabinoids.

Improving antibacterial prescribing safety in the management of COPD exacerbations: systematic review of observational and clinical studies on potential drug interactions associated with frequently prescribed antibacterials among COPD patients

Background

Guidelines advise the use of antibacterials (ABs) in the management of COPD exacerbations. COPD patients often have multiple comorbidities, such as diabetes mellitus and cardiac diseases, leading to polypharmacy. Consequently, drug–drug interactions (DDIs) may frequently occur, and may cause serious adverse events and treatment failure.

Objectives

(i) To review DDIs related to frequently prescribed ABs among COPD patients from observational and clinical studies. (ii) To improve AB prescribing safety in clinical practice by structuring DDIs according to comorbidities of COPD.

Methods

We conducted a systematic review by searching PubMed and Embase up to 8 February 2018 for clinical trials, cohort and case–control studies reporting DDIs of ABs used for COPD. Study design, subjects, sample size, pharmacological mechanism of DDI and effect of interaction were extracted. We evaluated levels of DDIs and quality of evidence according to established criteria and structured the data by possible comorbidities.

Results

In all, 318 articles were eligible for review, describing a wide range of drugs used for comorbidities and their potential DDIs with ABs. DDIs between ABs and co-administered drugs could be subdivided into: (i) co-administered drugs altering the pharmacokinetics of ABs; and (ii) ABs interfering with the pharmacokinetics of co-administered drugs. The DDIs could lead to therapeutic failures or toxicities.

Conclusions

DDIs related to ABs with clinical significance may involve a wide range of indicated drugs to treat comorbidities in COPD. The evidence presented can support (computer-supported) decision-making by health practitioners when prescribing ABs during COPD exacerbations in the case of co-medication.

Association Between the Prothrombin Time–International Normalized Ratio and Concomitant Use of Antibiotics in Warfarin Users: Focus on Type of Antibiotic and Susceptibility of Bacteroides fragilis to Antibiotics

Background:

The difference in type of antibiotics and susceptibility of Bacteroides fragilis to antibiotics may influence warfarin anticoagulation. However, these influences have not been clarified in clinical settings.

Objectives:

This study aimed to investigate association the between the prothrombin time–international normalized ratio (PT-INR) and concomitant use of antibiotics in a real-world population of warfarin users.

Methods:

This was a single-center cohort study using data from health records and included patients who received β-lactams (BLs)/fluoroquinolones (FQs) during ongoing warfarin treatment (2011-2015) at Hamamatsu University Hospital in Japan. Antibiotics were categorized into those to which B fragilis is susceptible (BLsus, FQsus) and those to which it is not (BLnon, FQnon) and into those given orally (BLpo, FQpo) or intravenously (BLiv, FQiv). Outcomes were excessive PT-INR and changes in PT-INR, defined as the ratio (INR ratio) and difference (ΔINR) of maximum PT-INR and baseline PT-INR. Excessive PT-INR was graded as INR ratio of >1.5 or >2.5.

Results:

A total of 1185 warfarin users were included. The proportion of INR ratio >2.5 in FQiv was higher than in BLiv (95% CI: 1.59-46.5). The proportions with an INR ratio of >1.5 in BLsus and FQsus were higher than in BLnon (1.72-14.1) and FQnon (1.05-9.36), respectively. ΔINR values in FQpo, FQiv, and FQsus were higher than those in BLpo, BLiv, and FQnon, respectively.

Conclusions and Relevance:

Concomitant use of FQs, or of antibiotics to which B fragilis is susceptible is associated with higher risk of excessive anticoagulation. These findings would contribute to safe and proper antibiotic treatment in warfarin users.

Drug-drug interactions with metronidazole and itraconazole in patients using acenocoumarol

PURPOSE

Various population-based cohort studies have shown that antimicrobial agents increase the risk of overanticoagulation in patients using coumarins. In this study, we assessed this association in hospitalized patients.

METHODS

We included all patients hospitalized in the Spaarne Gasthuis (Haarlem/Hoofddorp, the Netherlands), who started using an antimicrobial agent during acenocoumarol treatment or vice versa between 1 January 2015 and 1 July 2019. Patients were followed from start of concomitant therapy until 48 h after termination of the concomitant therapy or discharge, whichever came first. We analyzed the association between the antimicrobial agents and the risk of overanticoagulation, defined as an interpolated INR above 6, using Cox regression analysis. We corrected for multiple testing with the Bonferroni correction. Patients who started using acenocoumarol and amoxicillin/clavulanic acid were used as reference group.

RESULTS

In the study population, sixteen antimicrobial agents were started frequently concomitantly with acenocoumarol treatment. We included 2157 interaction episodes in 1172 patients. Patients who started using the combination of co-trimoxazole (HR 3.76; 95% CI 1.47-9.62; p = 0.006), metronidazole (HR 2.55; 95% CI 1.37-4.76; p = 0.003), or itraconazole (HR 4.11; 95% CI 1.79-9.45; p = 0.001) concomitantly with acenocoumarol treatment had an increased risk of overanticoagulation compared with patients using acenocoumarol and amoxicillin/clavulanic acid concomitantly. The associations for metronidazole (p = 0.045) and itraconazole (p = 0.015) remained statistically significant after correction for multiple testing.

CONCLUSION

Co-trimoxazole, metronidazole, and itraconazole increase the risk of overanticoagulation in patients using acenocoumarol. These combinations should be avoided if possible or otherwise acenocoumarol doses should be reduced and INR measured more frequently.

RGD-hirudin-based low molecular weight peptide prevents blood coagulation via subcutaneous injection

Thromboembolic disease is a common cardio-cerebral vascular disease that threatens human life and health. Thrombin not only affects the exogenous coagulation pathway, but also the endogenous pathway. Thus, it becomes one of the most important targets of anticoagulant drugs. RGD-hirudin is an anticoagulant drug targeting thrombin, but it can only be administered intravenously. We designed a low molecular weight peptide based on RGD-hirudin that could prevent blood clots. We first used NMR to identify the key amino acid residues of RGD-hirudin that interacted with thrombin. Then, we designed a novel direct thrombin inhibitor peptide (DTIP) based on the structure and function of RGD-hirudin using homology modeling. Molecular docking showed that the targeting and binding of DTIP with thrombin were similar to those of RGD-hirudin, suggesting DTIP interacted directly with thrombin. The active amino acids of DTIP were identified by alanine scanning, and mutants were successfully constructed. In blood clotting time tests in vitro, we found that aPTT, PT, and TT in the rat plasma added with DTIP were greatly prolonged than in that added with the mutants. Subcutaneous injection of DTIP in rats also could significantly prolong the clotting time. Thrombelastography analysis revealed that DTIP significantly delayed blood coagulation. Bio-layer interferometry study showed that there were no significant differences between DTIP and the mutants in thrombin affinity constants, suggesting that it might bind to other sites of thrombin rather than to its active center. Our results demonstrate that DTIP with low molecular weight can prevent thrombosis via subcutaneous injection.

Atrial Fibrillation and Bleeding in Patients With Chronic Lymphocytic Leukemia Treated with Ibrutinib in the Veterans Health Administration

BACKGROUND

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults. The introduction of novel oral agents, starting with ibrutinib in 2013, has revolutionized the therapeutic landscape; however, clinical trials have suggested an association between ibrutinib and the risk of bleeding-related adverse events and atrial fibrillation (Afib) in patients with CLL.

METHODS

Patients diagnosed and treated for CLL at the Veterans Health Administration (VHA) from 2010 to 2014 were followed until December 31, 2016, death, or lack of utilization of hematology/oncology services for ≥ 18 months; or until incidence of another cancer. Treatments dispensed, evidence of VHA system use, bleeding events, and Afib were determined from the administrative records, laboratory records, pharmacy dispensation records, and clinical notes in the electronic healthcare record.

RESULTS

From 2010 to 2014, 2,796 patients were diagnosed and received care for CLL within the VHA, of whom 172 patients received ibrutinib and 291 received bendamustine + rituximab (BR). The use of anticoagulants following induction therapy did not differ between BR and ibrutinib patients (9% vs 8%, respectively), nor did the use of antiplatelets agents (6% vs 2%, respectively). Of the 291 patients that received BR, 12 (4%) developed a bleeding event compared with 20 (12%) who received ibrutinib. Additionally, 13 (8%) ibrutinib patients developed Afib compared with 9 (3%) BR patients.

CONCLUSIONS

Real-world evidence from a nationwide cohort of patients with CLL suggests that while ibrutinib is associated with increased bleeding-related adverse events and Afib, the risk is comparable to those reported in previous clinical trials. These findings suggest that patients in real-world clinical care settings with higher levels of comorbidities may be at an increased risk for bleeding events and Afib.

Calculated parenteral initial therapy of bacterial infections: Antibiotic treatment in the elderly

This is the fifteenth chapter of the guideline “Calculated initial parenteral treatment of bacterial infections in adults – update 2018” in the 2^nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience.

Multimorbidity, an atypical symptomatology of infections in combination with multimedication, the associated interaction risks and serious consequences of synergistic side effects characterize the conditions when deciding on the use of antibiotics in old age. Strict decision regarding the indication itself, choice of the best antibiotic even considering rare side effects which may be dangerous in the elderly, determining the correct dose, dosing interval and the shortest possible duration according to the physiological status of the patient as well as monitoring effectiveness and toxicity detect expected and unexpected side effects early. Recommendations must reflect the peculiarities of antibiotic treatment in elderly patients.

Prospective evaluation of drug-drug interactions in ambulatory cancer patients initiated on prophylactic anticoagulation

INTRODUCTION

Drug options for VTE prophylaxis are increasing for ambulatory cancer patients and data regarding anticoagulant-drug interactions and their relationship to VTE and bleeding are needed to improve care.

METHODS

Over one year, 108 cancer patients with high VTE risk were prospectively identified. Potential anticoagulant-drug interactions were ascertained by chart review and graded on need for intervention. Providers selected anticoagulant prophylaxis based on potential drug interactions and patient-provider discussion. A cross-sectional analysis was performed thereafter to evaluate VTE and bleeding endpoints within one year of anticoagulant initiation.

RESULTS

The average number of potential drug interactions per patient was higher for warfarin than others (3.04 vs. 1.28 (apixaban), 1.02 (rivaroxaban), and 0.98 (LMWH)). The severity of the interactions based on grade was, for apixaban: 1.6% grade X, 50.8% grade D, and 47.5% grade C; for rivaroxaban: 2.1% grade X, 64.9% grade D, 33.0% grade C; for LMWH, 0% grade X, 66.7% grade D, 33.3% grade C; and for warfarin, 0% grade X, 29.4% grade D, 70.6% grade C. At the end of the investigational period, 11 bleeds and 7 VTEs were reported. Drug combinations significantly associated with an increased bleeding risk were crizotinib with apixaban or rivaroxaban and PPIs with warfarin. The use of sulfamethoxazole-trimethoprim with warfarin was associated with an increased VTE risk.

CONCLUSIONS

DOACs had fewer DDIs than warfarin, although interaction severity differed between anticoagulants. Some anticoagulant-drug interactions were associated with bleeding or VTE. Although not powered for analysis, DDI severity did not affect bleeding rates and inversely correlated with VTE risk.

Gut Microbiome and Response to Cardiovascular Drugs

The gut microbiome is emerging as an important contributor to both cardiovascular disease risk and metabolism of xenobiotics. Alterations in the intestinal microbiota are associated with atherosclerosis, dyslipidemia, hypertension, and heart failure. The microbiota have the ability to metabolize medications, which can results in altered drug pharmacokinetics and pharmacodynamics or formation of toxic metabolites which can interfere with drug response. Early evidence suggests that the gut microbiome modulates response to statins and antihypertensive medications. In this review, we will highlight mechanisms by which the gut microbiome facilitates the biotransformation of drugs and impacts pharmacological efficacy. A better understanding of the complex interactions of the gut microbiome, host factors, and response to medications will be important for the development of novel precision therapeutics for targeting CVD.

Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions

Oral anticoagulants are commonly prescribed but high risk to cause adverse events. Skilled drug interaction management is essential to ensure safe and effective use of these therapies. Clinically relevant interactions with warfarin include drugs that modify cytochrome 2C9, 3A4, or both. Drugs that modify p-glycoprotein may interact with all direct oral anticoagulants, and modifiers of cytochrome 3A4 may interact with rivaroxaban and apixaban. Antiplatelet agents, nonsteroidal anti-inflammatory drugs, and serotonergic agents, such as selective serotonin reuptake inhibitors, can increase risk of bleeding when combined with any oral anticoagulant, and concomitant use should be routinely assessed. New data on anticoagulant drug interactions are available almost daily, and therefore, it is vital that clinicians regularly search interaction databases and the literature for updated management strategies. Skilled drug interaction management will improve outcomes and prevent adverse events in patients taking oral anticoagulants.

Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions

Oral anticoagulants are commonly prescribed but high risk to cause adverse events. Skilled drug interaction management is essential to ensure safe and effective use of these therapies. Clinically relevant interactions with warfarin include drugs that modify cytochrome 2C9, 3A4, or both. Drugs that modify p-glycoprotein may interact with all direct oral anticoagulants, and modifiers of cytochrome 3A4 may interact with rivaroxaban and apixaban. Antiplatelet agents, nonsteroidal anti-inflammatory drugs, and serotonergic agents, such as selective serotonin reuptake inhibitors, can increase risk of bleeding when combined with any oral anticoagulant, and concomitant use should be routinely assessed. New data on anticoagulant drug interactions are available almost daily, and therefore, it is vital that clinicians regularly search interaction databases and the literature for updated management strategies. Skilled drug interaction management will improve outcomes and prevent adverse events in patients taking oral anticoagulants.

Reduced Effectiveness of Interruptive Drug-Drug Interaction Alerts after Conversion to a Commercial Electronic Health Record

BACKGROUND

Drug-drug interaction (DDI) alerts in electronic health records (EHRs) can help prevent adverse drug events, but such alerts are frequently overridden, raising concerns about their clinical usefulness and contribution to alert fatigue.

OBJECTIVE

To study the effect of conversion to a commercial EHR on DDI alert and acceptance rates.

DESIGN

Two before-and-after studies.

PARTICIPANTS

3277 clinicians who received a DDI alert in the outpatient setting.

INTERVENTION

Introduction of a new, commercial EHR and subsequent adjustment of DDI alerting criteria.

MAIN MEASURES

Alert burden and proportion of alerts accepted.

KEY RESULTS

Overall interruptive DDI alert burden increased by a factor of 6 from the legacy EHR to the commercial EHR. The acceptance rate for the most severe alerts fell from 100 to 8.4%, and from 29.3 to 7.5% for medium severity alerts (P < 0.001). After disabling the least severe alerts, total DDI alert burden fell by 50.5%, and acceptance of Tier 1 alerts rose from 9.1 to 12.7% (P < 0.01).

CONCLUSIONS

Changing from a highly tailored DDI alerting system to a more general one as part of an EHR conversion decreased acceptance of DDI alerts and increased alert burden on users. The decrease in acceptance rates cannot be fully explained by differences in the clinical knowledge base, nor can it be fully explained by alert fatigue associated with increased alert burden. Instead, workflow factors probably predominate, including timing of alerts in the prescribing process, lack of differentiation of more and less severe alerts, and features of how users interact with alerts.

Review of antimicrobial use and considerations in the elderly population

Pharmacologic management of infections in elderly patients presents multiple challenges to health care professionals due to variable pharmacokinetics, pharmacodynamics, and immune function. Age is a well-established risk factor for infection, but furthermore is a risk factor for prolonged length of hospital stay, increased incidence of complications, and significant and sustained decline in baseline functional status. In 2014, 46.2 million Americans were aged ≥65 years, accounting for 14.5% of the total population. By 2033, for the first time, the population of persons aged ≥65 years is projected to outnumber the people <18 years of age. According to the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey, 154 million prescriptions for antimicrobials were estimated to have been written in doctors’ offices and emergency departments during a 1-year time period. In 2014, 266.1 million courses of antimicrobials were dispensed to outpatients by US community pharmacies. A study that evaluated 2007–2009 Medicare Part D data found that patients aged ≥65 years used more antimicrobials, at 1.10 per person per year, compared to 0.88 antimicrobials used per person per year in patients aged 0–64 years. With the abundance of antimicrobial prescriptions and the current growth in the number and proportion of older adults in the US, it is essential that health care providers understand appropriate antimicrobial pharmacotherapy in the elderly patient. This review focuses on the use and implications of antimicrobial agents in the elderly population.

Preemptive warfarin dose reduction after initiation of sulfamethoxazole-trimethoprim or metronidazole

To evaluate the utility of a preemptive warfarin dose reduction at the time of initiation of either sulfamethoxazole-trimethoprim or metronidazole, a retrospective chart review of patients who received an outpatient prescription for warfarin and either sulfamethoxazole-trimethoprim and/or metronidazole from July 1, 2011 to July 1, 2015 was conducted. Clinical outcomes compared Veterans who had a warfarin dose reduction and those who did not within 120 h (5 days) of antibiotic initiation. The primary outcome compared the pre-and post-antibiotic International Normalized Ratio (INR) of patients in the intervention group (warfarin dose reduction) with those in the control group (no intervention). Secondary outcomes assessed incidence of thromboembolic and major bleeding events within 30 days of antibiotic completion. Fifty patients were assessed. Forty-nine patients had at least one follow-up appointment; 126 follow-up visits were evaluated. There was a statistically significant difference for the change in therapeutic INR at the first follow-up appointment (p = 0.029) for those patients in the control group. On average, the patients in the intervention group required fewer follow-up visits (p = 0.019). There were no statistically significant differences for the overall rate of therapeutic INR values between groups, as well as no instances of a thromboembolic or major bleeding events during the follow-up period. Clinically significant differences were observed for patients who received a preemptive warfarin dose reduction upon initiation of sulfamethoxazole-trimethoprim or metronidazole. Patients in the intervention group required fewer follow-up appointments and were more likely maintain a therapeutic INR within the 30 days following the antibiotic course. Results of this study will be presented the at Pharmacy and Therapeutics committee in an effort to seek approval for policy development to initiate a local preemptive warfarin dose adjustment as a standard of practice.

Problems in anticoagulation of a patient with antibiotic treatment for endocarditis: interaction of rifampicin and vitamin K antagonists

The cytochrome P450 is a superfamily of isoenzymes that are responsible for the metabolism of many drugs. Significant changes in pharmacokinetics and drug interactions may be due to induction of hepatic cytochrome P450 enzymes. Rifampicin is a common inducer of CYP3A4. We report a case of a 57-year-old woman who was suspected for endocarditis and therefore treated with rifampicin. Due to previous mechanical aortic valve replacement, she also received phenprocoumon for anticoagulation. Although continuing anticoagulant therapy, antibiotic coadministration led to normal international normalised ratio (INR) level. Fifteen days after the treatment with rifampicin ended, INR returned to therapeutic level.

Warfarin monitoring in nursing homes assessed by case histories. Do recommendations and electronic alerts affect judgements?

PURPOSE

Older adults treated with warfarin are prone to complications, and high-quality monitoring is essential. The aim of this case history based study was to assess the quality of warfarin monitoring in a routine situation, and in a situation with an antibiotic-warfarin interaction, before and after receiving an electronic alert.

MATERIALS AND METHODS

In April 2014, a national web-based survey with two case histories was distributed among Norwegian nursing home physicians and general practitioners working part-time in nursing homes. Case A represented a patient on stable warfarin treatment, but with a substantial INR increase within the therapeutic interval. Case B represented a more challenging patient with trimethoprim sulfamethoxazole (TMS) treatment due to pyelonephritis. In both cases, the physicians were asked to state the next warfarin dose and the INR recall interval. In case B, the physicians could change their suggestions after receiving an electronic alert on the TMS-warfarin interaction.

RESULTS

Three hundred and ninety eight physicians in 292 nursing homes responded. Suggested INR recall intervals and warfarin doses varied substantially in both cases. In case A, 61% gave acceptable answers according to published recommendations, while only 9% did so for case B. Regarding the TMS-warfarin interaction in case history B, the electronic alert increased the percentage of respondents correctly suggesting a dose reduction from 29% to 53%. Having an INR instrument in the nursing home was associated with shortened INR recall times.

CONCLUSIONS

Practical advice on handling of warfarin treatment and drug interactions is needed. Electronic alerts as presented in electronic medical records seem insufficient to change practice. Availability of INR instruments may be important regarding recall time.

High-risk prescribing in an Irish primary care population: trends and variation

AIMS

The aims of the present study were to examine the prevalence of high-risk prescribing (HRP) in community-dwelling adults in Ireland from 2011-2015 using consensus-validated indicators, factors associated with HRP, and the variation in HRP between general practitioners (GPs) and in the dispensing of high-risk prescriptions between pharmacies.

METHODS

A repeated cross-sectional national pharmacy claims database study was conducted. Prescribing indicators were based on those developed in formal consensus studies and applicable to pharmacy claims data. Multilevel logistic regression was used to examine factors associated with HRP and dispensing.

RESULTS

There were significant reductions in the rates of most indicators over time (P < 0.001). A total of 66 022 of 300 906 patients at risk in 2011 [21.9%, 95% confidence interval (CI) 21.8, 22.1%], and 42 109 of 278 469 in 2015 (15.1%, 95% CI 15.0, 15.3%), received ≥1 high-risk prescription (P < 0.001). In 2015, indicators with the highest rates of HRP were prescription of a nonsteroidal anti-inflammatory drug (NSAID) without gastroprotection in those ≥75 years (37.2% of those on NSAIDs), coprescription of warfarin and an antiplatelet agent or high-risk antibiotic (19.5% and 16.2% of those on warfarin, respectively) and prescription of digoxin ≥250 μg day^-1 in those ≥65 years (14.0% of those on digoxin). Any HRP increased significantly with age and number of chronic medications (P < 0.001). a) After controlling for patient variables, the variation in the rate of HRP between GPs was significant (P < 0.05); and b) after controlling for patient variables and the prescribing GP, the variation in the rate of dispensing of high-risk prescriptions between pharmacies was significant (P < 0.05).

CONCLUSIONS

HRP in Ireland has declined over time, although some indicators persist. The variation between GPs and pharmacies suggests the potential for improvement in safe medicines use in community care, particularly in vulnerable older populations.

Comparison of the Incidence of Major Bleeding With Rivaroxaban Use Among Nonvalvular Atrial Fibrillation Patients With Versus Without Diabetes Mellitus

Diabetes mellitus (DM) is a common co-morbidity in those with nonvalvular atrial fibrillation (NVAF). Most patients with DM and NVAF have a CHA₂DS₂-VASc score of ≥1 and should be considered for oral anticoagulation therapy for stroke prevention per treatment guidelines. The most important risk associated with anticoagulation is bleeding, which may be higher in those with NVAF plus DM. Our objective was to evaluate the incidence and characteristics of major bleeding (MB) in rivaroxaban users diagnosed with NVAF, further comparing those with DM versus those without DM, in a real-world clinical setting. Electronic medical records of >10 million patients from the Department of Defense Military Health System were queried to identify rivaroxaban users with NVAF over a 2.5-year period. Major bleeding-related hospitalization was identified by a validated case-finding algorithm. Patient characteristics, incidence and management of MB, and fatal outcomes were assessed by DM status. Of 44,793 rivaroxaban users with NVAF, 12,039 (26.9%) had DM, who were more likely men, younger, with more co-morbidity and higher CHA₂DS₂-VASc scores. Major bleeding incidence was higher among those with DM compared with those without, 3.68 (95% confidence interval [CI] 3.37 to 4.03) versus 2.51 (95% CI 2.34 to 2.69) per 100 person-years, and intracranial bleeding incidence was 0.19 (95% CI 0.13 to 0.28) versus 0.25 (95% CI 0.20 to 0.31) per 100 person-years. Fatal outcomes were rare for both cohorts, 0.09 per 100 person-years. In conclusion, in this post-marketing study of 44,793 rivaroxaban users with NVAF, patients with DM had more co-morbidities and higher incidence of MB compared with those without DM.

CHA2DS2-VASc Scores and Major Bleeding in Patients With Nonvalvular Atrial Fibrillation Who Are Receiving Rivaroxaban

STUDY OBJECTIVE

Assessing stroke risk associated with nonvalvular atrial fibrillation depends on the evaluation of patient characteristics and clinical features. Clinicians must determine that the net clinical benefit from anticoagulation therapy outweighs its risk, namely, bleeding. Risk assessment for stroke is commonly performed by calculating a CHA₂DS₂-VASc (congestive heart failure/left ventricular dysfunction, hypertension, ≥75 years, diabetes mellitus, previous stroke or transient ischemic attack or thromboembolism, vascular disease, aged 65 to 74 years, sex female) score. It is possible that CHA₂DS₂-VASc scores also have a relationship with the incidence of major bleeding. We examined the relationship between CHA₂DS₂-VASc scores and major bleeding in rivaroxaban users with nonvalvular atrial fibrillation.

METHODS

Electronic medical records of more than 10 million patients from the Department of Defense Military Health System were queried to identify patients with nonvalvular atrial fibrillation who received rivaroxaban from January 1, 2013, to June 30, 2015. Baseline characteristics of the study population were described by CHA₂DS₂-VASc scores and major bleeding status; major bleeding incidence was evaluated by CHA₂DS₂-VASc score category and for each CHA₂DS₂-VASc component.

RESULTS

Overall, 44,793 patients met the inclusion criteria for this analysis. The major bleeding incidence rate was 2.84 (95% confidence interval 2.69 to 3.00) per 100 person-years. The incidence of major bleeding increased from 0.30 to 5.40 per 100 person-years among patients with a CHA₂DS₂-VASc score of 0 to 5 or higher, respectively. Fatal outcomes among patients with major bleeding were positively correlated with CHA₂DS₂-VASc scores; patients with higher scores had higher mortality rates. The CHA₂DS₂-VASc component with the highest major bleeding incidence was for vascular disease, 5.69 (95% confidence interval 5.18 to 6.24) per 100 person-years.

CONCLUSION

Higher CHA₂DS₂-VASc scores are associated with increased incidence of major bleeding in nonvalvular atrial fibrillation patients receiving rivaroxaban.

Analysis of the first therapeutic-target-achieving time of warfarin therapy and associated factors in patients with pulmonary embolism

The present study aimed to investigate the factors affecting the first therapeutic-target-achieving (TTA) time of warfarin therapy in patients with acute pulmonary embolism (PTE). Between January 2008 and June 2013, patients with PTE confirmed by transpulmonary arterial enhanced computed tomographic pulmonary angiography or pulmonary ventilation perfusion scanning were included in the present study. Data collected included demographic information, history of tobacco and alcohol intake, basic diseases (stable and unstable hypertension, diabetes, heart failure, cancer/cerebral infarction, old myocardial infarction and atrial fibrillation), liver and kidney function, the haemoglobin and platelet count of the blood, international normalized ratio monitoring, warfarin dosage adjustment and medication combinations. Dynamic changes in international normalized ratio, anticoagulant efficacy, and adverse events within 90 days were monitored and analyzed. Univariate analysis demonstrated that the following factors affect the first TTA time: Initial dose, body mass index (BMI), liver function, heart failure, and the administration of levofloxacin, cephalosporins, and blood circulation-activating drugs. Logistic regression analysis revealed that the following were independent factors of the first TTA time: Initial dose, BMI, liver function, heart failure and levofloxacin. Therefore, the results of the present study demonstrated that various factors may affect the first TTA time of warfarin therapy, including the initial dose, BMI, liver function, heart function and concomitant medication.

Impact of a Guideline for the Management of Antimicrobial/Warfarin Interactions in the Inpatient Setting and Across Transition of Care

BACKGROUND

Drug-drug interactions (DDIs) with warfarin and antimicrobial agents are a common cause of international normalized ratio (INR) instability, which can affect the risk for bleeding and thrombotic events.

OBJECTIVE

The purpose of this study was to assess the impact of a comprehensive guideline for the management of warfarin-antimicrobial DDIs across transitions of care. The guideline emphasizes improving identification of significant antimicrobial-warfarin DDIs during hospitalization, empirical warfarin dose modification based on DDI and baseline INR, patient education, documentation of the DDI, communication with outpatient providers regarding the DDI and anticipated antimicrobial stop date, and warfarin dose adjustment on discontinuation of antimicrobial.

METHODS

This retrospective, single-center, quasiexperimental, pre-post study compared end points 3 months before and after guideline implementation. The primary outcome was time within therapeutic range (TTR).

RESULTS

The study included 78 preguideline and 31 postguideline patients; baseline characteristics were similar between groups. Implementation of the guideline resulted in greater in-hospital TTR (72% vs 50%, P = 0.04) and improved TTR across transition of care (70% vs 46%, P = 0.01). Documentation of DDI in the pharmacy anticoagulation discharge summary significantly improved in the postguideline group (40% vs 14%, P = 0.02) and numerically improved within the daily pharmacy progress notes (94% vs 82%, P = 0.13). The implementation of the guideline was associated with a nonsignificant, numerical reduction in bleeding events compared with the preguideline group (0 vs 4 events, P = 0.11).

CONCLUSION

This single-center approach to optimize the comprehensive management of significant antimicrobial-warfarin DDIs resulted in improved communication with outpatient providers and improved INR TTR.

Metronidazole reduces the expression of cytochrome P450 enzymes in HepaRG cells and cryopreserved human hepatocytes

1. Blood levels of S-warfarin have been reported to be increased by concomitant administration of metronidazole (MTZ), an antiprotozoal imidazole derivative. 2. To elucidate the mechanism of this interaction and to identify other possible drug-drug interactions, we conducted an in vitro study with the human hepatoma HepaRG cells and cryopreserved human hepatocytes on the ability of MTZ to reduce the expression of cytochrome P450 (CYP) as well as nuclear receptors that regulate the expression of these enzymes. 3. HepaRG cells and cryopreserved human hepatocytes were treated with MTZ (20 to 500 µM) and were then analyzed by real-time RT-PCR to determine mRNA levels of drug-metabolizing enzymes and nuclear receptors. 4. In both cells, the expressions of CYP2C8, CYP2C9, CYP3A4 and constitutive androstane receptor (CAR) were decreased by MTZ treatment. Particularly, in HepaRG cells, their mRNA levels were decreased by MTZ treatment in a concentration-dependent manner. 5. Our findings suggest that the interaction between MTZ and S-warfarin may be due to the MTZ-induced down-regulation of CYP2C9, the primary enzyme responsible for S-warfarin hydroxylation, and CAR, which regulates CYP2C9 expression. We also found that MTZ use may alter the disposition of drugs metabolized by the CYP isozymes investigated.

Potential use of NOACs in developing countries: pros and cons

PURPOSE

Although vitamin K antagonists (VKAs) are effective for long-term thromboprophylaxis in atrial fibrillation (AF), their limitations have led to widespread underutilisation, especially in the developing world. Novel oral anticoagulants (NOACs) have emerged as promising alternatives to VKAs, although there are some particular considerations and challenges to their introduction in developing countries. This review summarises the current state of antithrombotic management of AF in the developing world, explores the early evidence for the NOACs and describes some of the special considerations that must be taken into account when considering the role of the NOACs within developing countries' health care systems.

METHODS

A literature search was conducted via PubMed and Google Scholar to find articles published in English between the years 2000 to 2014. Search terms used were "atrial fibrillation", "oral anticoagulants", "warfarin", "NOACs", "dabigatran", "rivaroxaban", "apixaban", "edoxaban", "time in therapeutic range", "International Normalized Ratio" "cost-effectiveness", "stroke", "adverse-drug reactions" and "drug-drug interactions", together with the individual names of developing countries as listed by the World Bank. We reviewed the results of randomized clinical trials, relevant retrospective and prospective studies, case-studies and review articles.

RESULTS

Many developing countries lack or have sporadic data on the quality of AF management, making it difficult to anticipate the potential impact of NOACs in these settings. The utilisation of anticoagulants for AF appears highly variable in developing countries. Given the issues associated with VKA therapy in many developing countries, NOACs offer some potential advantages; however, there is insufficient evidence to advocate the widespread replacement of warfarin at present. VKAs may continue to have a role in selected patients or countries, especially if alternative monitoring strategies can be utilised.

CONCLUSION

The evaluation of the introduction of NOACs should consider safety, budget concerns and the quality of oral anticoagulation care achieved by each country. Prospective registries will be important in developing countries to better elucidate the comparative safety, efficacy and cost-effectiveness of NOACs and VKAs as NOACs are introduced into practice.