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

Frozen/Thawed Samples Can Replace Fresh Samples for Assignment of ISI to Secondary Thromboplastin Standards for Multiple Reagent/Instrument Combinations: Data to Support Possible Revision of WHO Guidelines

BACKGROUND

Calibration of thromboplastins is required for accurate calculation of the international normalised ratio (INR). Accurate INR results are required for optimal dosing of vitamin K antagonists. Decreases in vitamin K antagonist usage have made the recruitment of sample sets for international sensitivity index (ISI) calibrations more difficult. A possible solution to this would be to allow the use of frozen-thawed samples in place of fresh plasmas in the calibration of secondary standards.

OBJECTIVES

We investigated the effect of freezing and thawing samples before usage in ISI calibrations of secondary standards.

METHODS

Multiple reagent/instruments were tested to identify the degree of difference between a fresh sample ISI calibration and one performed on frozen-thawed samples. Where possible, the two ISI calibrations were performed on the same sample set. Alternatively, a separate set of samples from different patients was used.

RESULTS

The difference in ISI values was <3% for those datasets where the same samples were used, and <6% for those datasets where two sample sets were used. Additionally, other parameters required for a valid ISI calibration showed only minor differences-some calibrations showed fewer outliers in the frozen-thawed datasets. Mean normal prothrombin time for the international reference thromboplastins was <3.5% different across four different calibrations (two for rabbit thromboplastin and two for recombinant human thromboplastin).

CONCLUSIONS

This modification to the WHO guidelines would facilitate the recruitment of test plasmas in advance of calibration solving the problem of requiring availability of fresh patient samples with a range of INRs in a 5-h window.

TRIAL REGISTRATION

Not a part of any clinical trial.

Tailoring oral anticoagulant treatment in the era of multi-drug therapies for PAH and CTEPH

The use of oral anticoagulants in the management of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) presents distinct therapeutic challenges and benefits. In PAH, the benefits of oral anticoagulation are uncertain, with studies yielding mixed results on their efficacy and safety. Conversely, oral anticoagulants are a cornerstone in the treatment of CTEPH, where their use is consistently recommended to prevent recurrent thromboembolic events. The choice between vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) remains a significant clinical question, as each type presents advantages and potential drawbacks. Furthermore, drug-drug interactions (DDIs) with concomitant PAH and CTEPH treatments complicate anticoagulant management, necessitating careful consideration of individual patient regimens. This review examines the current evidence on oral anticoagulant use in PAH and CTEPH and discusses the implications of DDIs within a context of multi-drug treatments, including targeted drugs in PAH.

Trends in Venous Thromboembolism and Chemoprophylaxis Utilization in Elective Total Knee Arthroplasty From 2011 to 2020

BACKGROUND

Venous thromboembolism (VTE) is a feared complication of joint arthroplasty, leading to recent clinical practice guidelines aimed at VTE prevention and prophylaxis. However, limited studies have examined national changes in practice regarding chemoprophylaxis and the resultant changes in VTE rates. The purpose of this study was to identify: (1) the temporal trends in thrombotic complications; and (2) changes in chemoprophylaxis utilization in patients undergoing elective total knee arthroplasty (TKA).

METHODS

A retrospective study was conducted using a large all-payer claims dataset. Patients who underwent osteoarthritis-indicated TKA between 2011 and 2020 were identified. Annual rates of VTE, including deep vein thrombosis and pulmonary embolism, within 90 days of TKA were determined. Utilization patterns for postoperative aspirin and anticoagulant medications were observed. Temporal trends were analyzed with linear regression and the calculation of the cumulative annual growth rate. Multivariable logistic regression was conducted to account for the effects of age and comorbidities.

RESULTS

A total of 1,263,351 TKA patients were identified between 2011 and 2020. There were significant reductions in VTE rates (2.9% in 2011 to 1.8% in 2020), deep vein thrombosis rates (2.0% in 2011 to 1.3% in 2020), and pulmonary embolism rates (1.1% in 2011 to 0.6% in 2020). Postoperative utilization of aspirin increased from 5.9% in 2011 to 53.2% in 2020, whereas utilization of anticoagulants decreased from 94.1% in 2011 to 46.8% in 2020. Among anticoagulants, direct factor Xa inhibitors had the greatest increase in utilization (4.6 to 69.7%). The average reimbursement associated with VTE after TKA decreased from $18,061 in 2011 to $7,835 in 2020.

CONCLUSIONS

The incidence rate and economic burden of VTE after TKA have significantly declined since 2011. There has been a trend toward increased aspirin and direct oral anticoagulant utilization for postoperative chemoprophylaxis.

LEVEL OF EVIDENCE

Level III.

Practical Suggestions for an Optimal Management of Vitamin K Antagonists: Italian Federation of Centers for the Diagnosis of Thrombotic Disorders and the Surveillance of the Antithrombotic Therapies (FCSA) Position Paper

In the era of direct oral anticoagulants, vitamin K antagonists retain a clinically relevant role in thrombotic disorders. In Italy, approximately 20% of the patients on anticoagulant therapies receives a VKA, in most cases warfarin. The optimal management of this drug is challenging and cannot disregard its intricate and unpredictable pharmacokinetic properties and patient's thrombotic and bleeding risk. Several clinical issues encountered during warfarin treatment are still unanswered and are tentatively addressed by physicians. In this regard, the Italian Federation of Centers for the diagnosis of thrombotic disorders and the Surveillance of the Antithrombotic therapies (FCSA) provides some experience-based good clinical practice's suggestions on the following topics: (1) how to start the anticoagulant treatment with warfarin and warfarin induction regimen; (2) how to manage a subtherapeutic INR value; (3) how to manage a supratherapeutic INR value in asymptomatic patients; and (4) how to manage the association of warfarin with interfering drugs.

Warfarin and Polypharmacy Challenges in Sudan: Drug Interactions in Patient Cohort

Purpose

Warfarin plays an important role in anticoagulation therapy despite the availability of the newest oral anticoagulants, and achieving optimal anticoagulation is challenging due to its narrow therapeutic range and variable dose. This study aimed to highlight polypharmacy and drug interactions in patients receiving warfarin therapy at Medani Heart Centre, Sudan.

Methods

This retrospective hospital-based study was conducted from May 2017 to October 2018. Each concurrent medication prescribed for 104 patients was collected and checked for drug-drug interactions using Medscape Reference-Drug Interaction Checker. The data were analysed by using SPSS 20, and descriptive statistics were used.

Results

The results revealed that 95.2% of patients had more than three medications in their profile, (3-5), (6-9) and more than 10 medications were prescribed for 40.4%, 44.2% and 10.6% of patients, respectively. A total of 93.3% of patients had drug-drug interactions, as follows: (1-5), (6-10), (11-15), (16-20) and more than 20 drug-drug interactions were found in 31.7%, 32.7%, 19.2%, 5.8% and 3.8% of patients, respectively. A total of 178 warfarin-drug interactions were identified in 88.5% of the patients. The INR ranged between 2 and 2.99 in 13.4% of patients, and INR values below 2 and above 5 were found in 44.2% and 21.2% of patients, respectively. Analgesics (n=54; 30.3%), cardiovascular drugs (n=51; 28.6%), and anticoagulants (n=46; 25.8%) were the most common drug classes that interact with warfarin. Significant and serious types of interactions with warfarin were found in 51% and 37.5% of patients, respectively.

Conclusion

This study highlights the complexity of managing warfarin therapy amid prevalent polypharmacy. A substantial majority of patients experienced multiple drug interactions. The identification of significant and serious interactions emphasizes the need for vigilant management strategies, including improved communication among healthcare professionals and targeted education for both providers and patients, to enhance the safety and efficacy of warfarin therapy.

Deep graph contrastive learning model for drug-drug interaction prediction

Drug-drug interaction (DDI) is the combined effects of multiple drugs taken together, which can either enhance or reduce each other's efficacy. Thus, drug interaction analysis plays an important role in improving treatment effectiveness and patient safety. It has become a new challenge to use computational methods to accelerate drug interaction time and reduce its cost-effectiveness. The existing methods often do not fully explore the relationship between the structural information and the functional information of drug molecules, resulting in low prediction accuracy for drug interactions, poor generalization, and other issues. In this paper, we propose a novel method, which is a deep graph contrastive learning model for drug-drug interaction prediction (DeepGCL for brevity). DeepGCL incorporates a contrastive learning component to enhance the consistency of information between different views (molecular structure and interaction network), which means that the DeepGCL model predicts drug interactions by integrating molecular structure features and interaction network topology features. Experimental results show that DeepGCL achieves better performance than other methods in all datasets. Moreover, we conducted many experiments to analyze the necessity of each component of the model and the robustness of the model, which also showed promising results. The source code of DeepGCL is freely available at https://github.com/jzysj/DeepGCL.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Patients With Atrial Fibrillation" provides recommendations to guide clinicians in the treatment of patients with atrial fibrillation.

METHODS

A comprehensive literature search was conducted from May 12, 2022, to November 3, 2022, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through November 2022, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Atrial fibrillation is the most sustained common arrhythmia, and its incidence and prevalence are increasing in the United States and globally. Recommendations from the "2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" and the "2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation" have been updated with new evidence to guide clinicians. In addition, new recommendations addressing atrial fibrillation and thromboembolic risk assessment, anticoagulation, left atrial appendage occlusion, atrial fibrillation catheter or surgical ablation, and risk factor modification and atrial fibrillation prevention have been developed.

Safety Issues of Herb-Warfarin Interactions

Warfarin is a popular anticoagulant with high global demand. However, studies have underlined serious safety issues when warfarin is consumed concomitantly with herbs or its formulations. This review aimed to highlight the mechanisms behind herb-warfarin interactions while laying special emphasis on its PKPD interactions and evidence on Herb-Warfarin Interaction (HWI) with regards to three different scenarios, such as when warfarin is consumed with herbs, taken as foods or prescribed as medicine, or when used in special situations. A targeted literature methodology involving different scientific databases was adopted for acquiring information on the subject of HWIs. Results of the present study revealed some of the fatal consequences of HWI, including post-operative bleeding, thrombosis, subarachnoid hemorrhage, and subdural hematomas occurring as a result of interactions between warfarin and herbs or commonly associated food products from Hypericum perforatum, Zingiber officinale, Vaccinium oxycoccos, Citrus paradisi, and Punica granatum. In terms of PK-PD parameters, herbs, such as Coptis chinensis Franch. and Phellodendron amurense Rupr., were found to compete with warfarin for binding with plasma proteins, leading to an increase in free warfarin levels in the bloodstream, resulting in its augmented antithrombic effect. Besides, HWIs were also found to decrease International Normalised Ratio (INR) levels following the consumption of Persea americana or avocado. Therefore, there is an urgent need for an up-to-date interaction database to educate patients and healthcare providers on these interactions, besides promoting the adoption of novel technologies, such as natural language processing, by healthcare professionals to guide them in making informed decisions to avoid HWIs.

Exploring safety and efficacy of rivaroxaban after living donor liver transplantation: a retrospective study

PURPOSE

Thromboembolic complications remain a significant concern in postoperative patients, particularly those who have undergone liver transplantation. Warfarin has been the standard oral anticoagulant. Direct oral anticoagulants (DOACs) have several advantages over warfarin, including rapid onset of action and standardized dose guidelines. We aimed to assess the safety of rivaroxaban in living donor liver transplantation (LDLT) recipients.

METHODS

This study was a single-center, retrospective descriptive analysis of LDLT recipients who received rivaroxaban between December 2020 and April 2022. A total of 27 recipients received rivaroxaban postoperatively. Liver function tests, immunosuppression levels, serum creatinine, and INR were recorded before the initiation of rivaroxaban and then on post-therapy days 1, 7, 14, 28, 90, and 180.

RESULTS

Among the 27 recipients receiving rivaroxaban postoperatively, portal venous thrombosis was the most prevalent indication for anticoagulation (44.4%), followed by Budd-Chiari syndrome (29.6%). Nine patients had a twofold increase in either ALT or AST values, two of whom were treated for biliary strictures and the others for rejection. Eighteen patients were given tacrolimus, and eight were on cyclosporine, with one patient switched from tacrolimus to cyclosporine due to insufficient therapeutic levels. There were no incidents of bleeding or re-thrombosis during the 180-day follow-up period.

CONCLUSION

Rivaroxaban may be a safe and effective alternative in LDLT recipients with no significant adverse incidents. Further studies with larger sample sizes are needed to confirm these findings and determine this population's optimal dose and duration of rivaroxaban therapy.

Non-vitamin K Antagonist Oral Anticoagulants (NOACs) Versus Warfarin in Patients with Atrial Fibrillation Using P-gp and/or CYP450-Interacting Drugs: a Systematic Review and Meta-analysis

PURPOSE

Non-vitamin K antagonist oral anticoagulants (NOACs) are excreted by P-glycoprotein (P-gp) and some are metabolized by CYP450 enzymes such as CYP3A4. Although fewer drug interactions are present with NOACs, it is unclear whether NOACs should also be preferred over vitamin K antagonists (VKAs) in patients with atrial fibrillation (AF) using pharmacokinetically interacting drugs. Therefore, the benefit-risk profile of NOACs versus VKAs was investigated in AF patients treated with P-gp and/or CYP450-interacting drugs.

METHODS

Using PubMed and Embase, randomized controlled trials and observational studies on the effectiveness and safety of NOACs versus VKAs in AF patients using P-gp and/or CYP450-interacting drugs were included. A meta-analysis was performed, calculating relative risks (RR) and 95% confidence intervals (CI) with the Mantel-Haenszel method.

RESULTS

Twelve studies were included, investigating 10,793 NOAC and 10,096 VKA users treated with P-gp/CYP3A4 inhibitors, whereas no studies on P-gp and/or CYP450-inducing drugs were identified. Compared to VKAs, NOACs were associated with a borderline non-significantly lower stroke or systemic embolism (stroke/SE) risk (RR 0.85, 95%CI (0.72-1.01)), significantly lower intracranial bleeding (RR 0.47, 95%CI (0.34-0.65)) and all-cause mortality risks (RR 0.87, 95%CI (0.79-0.95), but significantly higher gastrointestinal bleeding risk (RR 1.74, 95%CI (1.06-2.86)). Among AF patients using amiodarone, NOACs were associated with significantly lower stroke/SE (RR 0.71, 95%CI (0.54-0.93)) and intracranial bleeding risks (RR 0.51, 95%CI (0.29-0.88)), but significantly higher gastrointestinal bleeding risk (RR 2.15, 95%CI (1.24-3.72)) than VKAs.

CONCLUSION

The benefit-risk profile of NOACs compared to VKAs was preserved in AF patients using P-gp/CYP3A4 inhibitors, including amiodarone.

Multistage Anticoagulant Surfaces: A Synergistic Combination of Protein Resistance, Fibrinolysis, and Endothelialization

Anticoagulant surface modification of blood-contacting materials has been shown to be effective in preventing thrombosis and reducing the dose of anticoagulant drugs that patients take. However, commercially available anticoagulant coatings, that is, both bioinert and bioactive coatings, are typically based on a single anticoagulation strategy. This puts the anticoagulation function of the coating at risk of failure during long-term use. Considering the several pathways of the human coagulation system, the synergy of multiple anticoagulation theories may provide separate, targeted effects at different stages of thrombosis. Based on this presumption, in this work, negatively charged poly(sodium p-styrenesulfonate-co-oligo(ethylene glycol) methyl ether methacrylate) and positively charged poly(lysine-co-1-adamantan-1-ylmethyl methacrylate) were synthesized to construct matrix layers on the substrate by electrostatic layer-by-layer self-assembly (LBL). Amino-functionalized β-cyclodextrin (β-CD-PEI) was subsequently immobilized on the surface by host-guest interactions, and heparin was grafted. By adjusting the content of poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA), the interactions between modified surfaces and plasma proteins/cells were regulated. This multistage anticoagulant surface exhibits inertness at the initial stage of implantation, resisting nonspecific protein adsorption (POEGMA). When coagulation reactions occur, heparin exerts its active anticoagulant function in a timely manner, blocking the pathway of thrombosis. If thrombus formation is inevitable, lysine can play a fibrinolytic role in dissolving fibrin clots. Finally, during implantation, endothelial cells continue to adhere and proliferate on the surface, forming an endothelial layer, which meets the blood compatibility requirements. This method provides a new approach to construct a multistage anticoagulant surface for blood-contacting materials.

Integrated analysis of clinical and genetic factors on the interindividual variation of warfarin anticoagulation efficacy in clinical practice

AIM

The anticoagulation effect of warfarin is usually evaluated by percentage of time in therapeutic range (PTTR), which is negatively correlated with the risk of warfarin adverse reactions. This study aimed to explore the effects of genetic and nongenetic factors on anticoagulation efficacy of warfarin during different therapeutic range.

METHODS

We conducted an observational retrospective study aiming at evaluating the impact of clinical and genetic factors on PTTR from initial to more than six months treatment. This analysis included patients with heart valve replace (HVR) surgery who underwent long-term or life-long time treatment with standard-dose warfarin for anticoagulation control in Second Xiangya Hospital. All patients were followed for at least 6 months. We genotyped single nucleotide polymorphisms in VKORC1 and CYP2C9 associated with altered warfarin dose requirements and tested their associations with PTTR.

RESULTS

A total of 629 patients with intact clinical data and available genotype data were enrolled in this study, and only 38.63% patients achieved good anticoagulation control (PTTR > 0.6). Clinical factors, including male gender, older age, overweight, AVR surgery and stroke history, were associated with higher PTTR. Patients with VKORC1 -1639AA genotype had significantly higher PTTR level compared with GA/GG genotype carriers only in the first month of treatment. Patients with CYP2C9*3 allele had higher PTTR compared with CYP2C9*1*1 carriers. Moreover, compared with VKORC1 -1639 AG/GG carriers, INR > 4 was more likely to be present in patients with AA genotype. The frequency of CYP2C9*1*3 in patients with INR > 4 was significantly higher than these without INR > 4.

CONCLUSION

We confirmed the relevant factors of warfarin anticoagulation control, including genetic factors (VKORC1 -1639G > A and CYP2C9*3 polymorphisms) and clinical factors (male gender, older age, overweight, AVR surgery and stroke history), which could be helpful to individualize warfarin dosage and improve warfarin anticoagulation control during different treatment period.

Predictors of bleeding events in acute decompensated heart failure patients with antithrombotic therapy: AURORA study

AIMS

Heart failure (HF) is reported to be one of the major risks of bleeding events. On the other hand, HF patients frequently receive anticoagulants or antiplatelet therapy to manage various co-morbidities. However, predictors of bleeding events in patients with HF have rarely been reported. This study aimed to evaluate the predictors of bleeding events and relationship between bleeding events and HF re-hospitalizations.

METHODS AND RESULTS

We included 1660 acute decompensated heart failure (ADHF) patients from the AURORA registry between January 2015 and December 2020. A total of 1429 patients were excluded because of history of HF admission, missing echocardiographic data at discharge, lost to follow-up, haemodialysis and no antithrombotic drugs. Finally, we evaluated 231 patients from AURORA registry. The bleeding events were defined as Type 2 to 5 bleeding according to the Bleeding Academic Research Consortium definition. We divided our patients into the bleeding group and non-bleeding group. We compared the baseline characteristics, medications, laboratory data, and echocardiographic data between the two groups. Median age was 78 (IQR 71-82) years old and male accounted for 59%. Approximately half of the patients had an antiplatelet therapy and 70% had an anticoagulant therapy. During a median follow-up of 651 (IQR 357-1139) days, 32 patients (13.8%) suffered from bleeding events. The major driver of the registered events was gastrointestinal bleeding (n = 21, 65.6%), and the other events were cerebral bleeding (n = 4, 12.5%), intraarticular bleeding (n = 2, 6.3%), urogenital bleeding (n = 2, 6.3%), haemorrhagic pericardial effusions (n = 1, 3.1%), subcutaneous hematomas (n = 1, 3.1%), and haemothorax (n = 1, 3.1%). There was a significantly lower haemoglobin level (P < 0.01), higher proportion of inferior vena cava (IVC) diameter ≥21 mm (P < 0.01), and higher furosemide equivalent doses per kilogram (P < 0.01) in the bleeding group than non-bleeding group. A multivariate analysis revealed an equivalent dose of furosemide per kilogram ≥0.66 mg/kg (hazard ratios (HR) of 2.64, 95% confidence interval (CI) 1.26-5.68, P = 0.01), haemoglobin ≤10.3 g/dL (HR of 2.43, 95% CI 1.14-5.03, P = 0.02), and IVC diameter ≥21 mm (HR of 2.79, 95% CI 1.16-6.29, P = 0.02) were independently associated with bleeding events. The Kaplan-Meier analysis showed that HF re-hospitalization rates were higher in the bleeding group than non-bleeding group (P = 0.04).

CONCLUSIONS

High doses of oral loop diuretics, IVC dilatation, and anaemia were predictors of bleeding events in patients hospitalized with ADHF patients. In addition, bleeding events were associated with HF re-hospitalizations.

Selective Serotonin Reuptake Inhibitor (SSRI) Bleeding Risk: Considerations for the Consult-Liaison Psychiatrist

PURPOSE OF REVIEW

To present a clinically oriented review of selective serotonin reuptake inhibitor (SSRI)-related bleeding issues commonly addressed by consult-liaison psychiatrists.

RECENT FINDINGS

Concomitant medical, surgical, or hospital-based conditions exacerbate the risk of SSRI-related bleeding even though a review of the literature suggests it is only marginally elevated. Psychiatrists and other clinicians need to consider these conditions along with antidepressant benefits when answering the question: to start, hold, continue, or change the antidepressant? Where an evidence base is limited, mechanistic understanding may help consult-liaison psychiatrists navigate this terrain and collaborate with other medical specialties on responsible antidepressant management. Most often, the risk is cumulative; data are not directly applicable to complex clinical situations. This review incorporates a hematologic perspective and approach to bleeding risk assessment along with extant data on SSRI-induced bleeding risk ad specific medical conditions.

[Drug interactions in neurosurgical patients]

We analyzed literature data on the most common drug interactions in neurosurgical patients. Drug interactions are a potential cause of adverse and dangerous clinical events and outcomes. Awareness of nature of drug interactions is valuable to avoid negative consequences when using combination of several drugs. Polypharmacy in neurosurgical patients is caused by treatment of intracranial lesions (hormonal therapy, antiepileptic drugs, etc.) and concomitant somatic diseases that increases the risk of drug interactions.

Concomitant administration of warfarin and toremifene: A case report

WHAT IS KNOWN AND OBJECTIVE

Antiestrogen agents have been reported to enhance the anticoagulant activity of warfarin. The use of tamoxifen with warfarin has been contraindicated. However, warfarin in combination with toremifene has not been reported. We report a case in which warfarin was combined with toremifene and applied warfarin dose prediction models to predict the dose of warfarin.

CASE SUMMARY

We report the case of a 50-year-old woman with a history of breast cancer, who underwent long-term toremifene therapy after mastectomy. The patient was treated with warfarin after prosthetic valve replacement and had a fluctuating international normalized ratio (INR) following the concomitant administration of toremifene. We applied the warfarin dose prediction model to adjust the warfarin dose during treatment. Finally, her INR stabilized with a lower dose of warfarin, and there was no serious bleeding during the 1-year follow-up.

WHAT IS NEW AND CONCLUSION

Warfarin does not have a serious interaction with toremifene in this case, but it needed about 37.5% dose reduction which was comparable to the interaction of some common antibiotics with warfarin.

Does coprescribing nonsteroidal anti-inflammatory drugs and oral anticoagulants increase the risk of major bleeding, stroke and systemic embolism?

AIMS

To examine the risk of gastrointestinal (GI) bleeding, major bleeding, stroke and systemic embolism associated with prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) to adults receiving oral anticoagulant (OAC) therapy.

METHODS

We conducted a population-based cohort study in adults receiving OAC therapy using linked primary care (Clinical Practice Research Datalink GOLD) and hospital (Hospital Episodes Statistics) electronic health records. We used cause-specific Cox regression models with time-dependent NSAID treatment in a propensity score matched population to estimate the increased risk of GI bleeding, stroke, major bleeding and systemic embolism associated with NSAID use.

RESULTS

The matched cohort contained 3177 patients with OAC therapy alone and 3177 with at least 1 concomitant NSAID prescription. Compared with OAC therapy alone, concomitant prescription of NSAIDs with OACs was associated with increased risk of GI bleeding (hazard ratio [HR] 3.01, 95% confidence interval [CI] 1.63 to 5.55), stroke (HR 2.71, 95% CI 1.48 to 4.96) and major bleeding (HR 2.77, 95% CI 1.84 to 4.19). The association with systemic embolism did not reach statistical significance (HR 3.02, 95% CI 0.82 to 11.07). Sensitivity analyses indicated that the results were robust to changes in exclusion criteria and the choice of potential confounding variables.

CONCLUSION

When OACs are coprescribed with NSAIDs, the risk of adverse bleeding events increases and, simultaneously, the protective effect of OACs to prevent strokes reduces. There is a need for interventions that reduce hazardous prescribing of NSAIDs in people receiving OAC therapy.

Dilemmas in the Choice of Adequate Therapeutic Treatment in Patients with Acute Pulmonary Embolism—From Modern Recommendations to Clinical Application

Pulmonary thromboembolism is a very common cardiovascular disease, with a high mortality rate. Despite the clear guidelines, this disease still represents a great challenge both in diagnosis and treatment. The heterogeneous clinical picture, often without pathognomonic signs and symptoms, represents a huge differential diagnostic problem even for experienced doctors. The decisions surrounding this therapeutic regimen also represent a major dilemma in the group of patients who are hemodynamically stable at initial presentation and have signs of right ventricular (RV) dysfunction proven by echocardiography and positive biomarker values (pulmonary embolism of intermediate–high risk). Studies have shown conflicting results about the benefit of using fibrinolytic therapy in this group of patients until hemodynamic decompensation, due to the risk of major bleeding. The latest recommendations give preference to new oral anticoagulants (NOACs) compared to vitamin K antagonists (VKA), except for certain categories of patients (patients with antiphospholipid syndrome, mechanical valves, pregnancy). When using oral anticoagulant therapy, special attention should be paid to drug–drug interactions, which can lead to many complications, even to the death of the patient. Special population groups such as pregnant women, obese patients, patients with antiphospholipid syndrome and the incidence of cancer represent a great therapeutic challenge in the application of anticoagulant therapy. In these patients, not only must the effectiveness of the drugs be taken into account, but great attention must be paid to their safety and possible side effects, which is why a multidisciplinary approach is emphasized in order to provide the best therapeutic option.

Protective effect of proton pump inhibitor against gastrointestinal bleeding in patients receiving oral anticoagulants: A systematic review and meta-analysis

AIM

The evidence of a protective effect of proton pump inhibitor (PPI) in oral anticoagulant (OAC) treated patients against gastrointestinal bleeding (GIB) is still lacking. We conducted a meta-analysis to estimate the risk of GIB in patients with OAC and PPI co-therapy.

METHODS

A systematic search of PubMed, EMBASE, Cochrane, and Scopus databases was performed for studies reporting GIB risk in OAC and PPI co-therapy. Primary outcomes were total GIB and major GIB events. Pooled estimates of GIB risk were calculated by a random-effect meta-analysis and reported as odds ratios (OR) and 95% confidence interval (CI).

RESULTS

A total of 10 studies and 1,970,931 patients were included. OAC and PPI co-therapy were associated with a lower odds of total and major GIB; OR (95% CI) was 0.67 (0.62-0.74) for total and 0.68 (0.63-0.75) for major GIB, respectively. No differences in the GIB of PPI co-therapy were observed between Asians and non-Asians (p-for-difference, total GIB=0.70, major GIB=0.75, respectively). For all kinds of OAC except for edoxaban, PPI cotreatment was related to a lower odds of GIB by 24-44%. The protective effect of PPI on total GIB was more significant in concurrent antiplatelets or non-steroidal anti-inflammatory drug users and those with high bleeding risks: patients with previous GIB history, HAS-BLED ≥3, or underlying gastrointestinal diseases.

CONCLUSION

In patients who receive OAC, PPI co-therapy is associated with a lower total and major GIB irrespective of ethnic group and OAC type, except for edoxaban. PPI co-therapy can be considered particularly in high GIB risk patients.

An update on drug-drug interactions associated with proton pump inhibitors

INTRODUCTION

Proton pump inhibitors (PPIs) block the gastric H/K-ATPase, therefore inhibiting acid gastric secretion, leading to an increased pH (>4). They account for an extremely high number of prescriptions worldwide. Numerous drug-drug interactions have been described with PPIs, but all the described interactions do not have clinical significance.

AREAS COVERED

This review will discuss the latest updates on drug-drug interactions with PPIs, focusing on the last ten-year publications in the following areas: anti-infective agents, anticancer drugs, antiplatelet agents and anticoagulants, and antidiabetics.

EXPERT OPINION

Although pharmacokinetic interactions of PPIs have been described with many drugs, their clinical relevance remains controversial. However, given the extremely high number of people being treated with PPIs, clinicians should remain vigilant for interactions that may be clinically significant and require dose adjustment or therapeutic monitoring. Interestingly, not all PPIs have the same pharmacokinetic and pharmacodynamic profile, with some having a strong potential to inhibit CYP2C19, such as omeprazole, esomeprazole and lansoprazole, while others, pantoprazole, rabeprazole and dexlansoprazole, are weak CYP2C19 inhibitors. These may be preferred depending on co-prescribed treatments.In addition, new formulations have been developed to prevent some of the gastric pH-dependent drug interactions and should be evaluated in further large-scale prospective comparative studies.

Association of direct oral anticoagulant-proton pump inhibitor cotherapy with adverse outcomes: protocol for a population-based cohort study

INTRODUCTION

Proton pump inhibitors (PPIs) are widely used for primary and secondary prevention of upper gastrointestinal bleeding. However, there remains controversy about the overall net clinical benefit of PPIs (omeprazole, rabeprazole, pantoprazole, lansoprazole) when coprescribed with direct oral anticoagulants (DOACs; dabigatran, rivaroxaban, apixaban, edoxaban). Our objective is to explore the risk of clinically relevant events, including bleeding, thromboembolic events and death, in patients prescribed DOACs while taking PPIs versus no PPI.

METHODS AND ANALYSIS

The protocol describes a retrospective cohort study of all Ontario residents aged 66 years or older with atrial fibrillation and at least one pharmacy dispensation for a DOAC identified using linked administrative healthcare databases covering 2009-2020. Ontario drug benefit dispensation records will be used to ascertain PPI exposure during DOAC therapy. The primary outcome is a composite of clinically relevant bleeding, thrombotic events or all-cause death. A minimum of 520 patients in total with at least one of the components of the composite outcome are needed. Poisson regression with a generalised estimating equation model will be used to calculate the adjusted incidence rate difference, incidence rate ratios 95% CI, adjusting for propensity for PPI use using inverse probability of treatment weights.

ETHICS AND DISSEMINATION

This research is exempt from REB review under section 45 of Ontario's Personal Health Information Protection Act. We will report our findings in a peer-reviewed biomedical journal and present them at conferences. The study will provide useful evidence to optimise the coprescription of DOACs and PPIs in practice.

Nonlinear Machine Learning in Warfarin Dose Prediction: Insights from Contemporary Modelling Studies

Objective: This study aimed to systematically assess the characteristics and risk of bias of previous studies that have investigated nonlinear machine learning algorithms for warfarin dose prediction. Methods: We systematically searched PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), China Biology Medicine (CBM), China Science and Technology Journal Database (VIP), and Wanfang Database up to March 2022. We assessed the general characteristics of the included studies with respect to the participants, predictors, model development, and model evaluation. The methodological quality of the studies was determined, and the risk of bias was evaluated using the Prediction model Risk of Bias Assessment Tool (PROBAST). Results: From a total of 8996 studies, 23 were assessed in this study, of which 23 (100%) were retrospective, and 11 studies focused on the Asian population. The most common demographic and clinical predictors were age (21/23, 91%), weight (17/23, 74%), height (12/23, 52%), and amiodarone combination (11/23, 48%), while CYP2C9 (14/23, 61%), VKORC1 (14/23, 61%), and CYP4F2 (5/23, 22%) were the most common genetic predictors. Of the included studies, the MAE ranged from 1.47 to 10.86 mg/week in model development studies, from 2.42 to 5.18 mg/week in model development with external validation (same data) studies, from 12.07 to 17.59 mg/week in model development with external validation (another data) studies, and from 4.40 to 4.84 mg/week in model external validation studies. All studies were evaluated as having a high risk of bias. Factors contributing to the risk of bias include inappropriate exclusion of participants (10/23, 43%), small sample size (15/23, 65%), poor handling of missing data (20/23, 87%), and incorrect method of selecting predictors (8/23, 35%). Conclusions: Most studies on nonlinear-machine-learning-based warfarin prediction models show poor methodological quality and have a high risk of bias. The analysis domain is the major contributor to the overall high risk of bias. External validity and model reproducibility are lacking in most studies. Future studies should focus on external validity, diminish risk of bias, and enhance real-world clinical relevance.

Does ramadan fasting affect the therapeutic and clinical outcomes of warfarin? a systematic review and meta-analysis

BACKGROUND

Warfarin's therapeutic effect is affected by many factors, including diet modifications. The impact of Ramadan fasting on warfarin is controversial. The aim of this systematic review and meta-analysis was to investigate the effect of Ramadan fasting on patients taking warfarin.

METHODS

A literature search was done in PubMed, WOS, Scopus, and Embase from inception to May 24, 2021. All relevant studies measuring the international normalized ratio (INR), time in therapeutic range (TTR), or the number of patients within therapeutic range before, during, and after Ramadan were assessed by full-text screening for achieving all of the inclusion criteria. We used the Newcastle-Ottawa Scale for quality assessment and RevMan 5.4 software for meta-analysis.

RESULTS

A total of five studies with 446 patients were included in the meta-analysis. The patients served as their own control. Our pooled analyses showed no significant difference during Ramadan compared to pre-Ramadan (MD: 0.08; 95% CI: - 0.00, 0.15; P = 0.06) and post-Ramadan (MD: - 0.00; 95% CI: - 0.14, 0.14; P = 1.00, respectively). There was only a significant increase in the risk ratio of supratherapeutic INR when comparing post-Ramadan vs. pre-Ramadan (RR: 1.69; 95% CI: 1.22, 2.33; P = 0.001). However, there was no significant risk for supratherapeutic INR during Ramadan compared to pre-Ramadan or post-Ramadan; the number of patients within the therapeutic range of INR during Ramadan compared to pre-Ramadan; and TTR during Ramadan, pre-Ramadan, and post-Ramadan.

CONCLUSION

Ramadan fasting did not affect INR level, TTR, or the number of patients within the therapeutic range before, during, and after Ramadan. However, there was a possibility of achieving a supratherapeutic INR post-Ramadan compared to pre-Ramadan. Therefore, INR monitoring and warfarin dose adjustments accordingly are recommended after Ramadan.

Prevention of nNon-Vitamin K Oral Anticoagulants-Related Gastrointestinal Bleeding With Acid Suppressants: A Systematic Review and Meta-Analysis

Whether the use of acid suppressants can reduce non-vitamin K oral anticoagulants (NOACs)-related gastrointestinal bleeding (GIB) remains unclear. To systemically evaluate the effect of acid suppressants on the risk of GIB in patients treated with NOACs. All related studies were searched in four databases (Cochrane, Embase, PubMed, and Web of Science) from their establishment to August 10, 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used to identify studies and Stata 16.0 software was used for meta-analysis, including sensitivity and subgroup analysis. Six retrospective cohort studies were included in this study. The use of acid suppressants significantly reduced the GIB risk in patients taking NOACs, with an overall relative risk (RR) of 0.70 (95% confidence interval [CI]: 0.61-0.82; P < 0.001; I² = 56.3%). This trend of reduced risk for GIB in NOACs was more significant in upper GIB (UGIB; RR: 0.45; 95%CI: 0.22-0.90; P = 0.025; I² = 71.1%). The reduction was stronger for dabigatran than for rivaroxaban and apixaban. The least reduction in the risk of GIB with acid suppressant co-therapy was rivaroxaban (dabigatran: RR: 0.53; 95% CI: 0.45-0.62; P = <0.001; I² = 39.8%; apixaban: RR: 0.67; 95% CI: 0.54-0.84; P = <0.001; I² = 0; rivaroxaban: RR: 0.73; 95% CI: 0.66-0.81; P = <0.001; I² = 37.6%). The included studies revealed the protective effect of acid suppressants against NOACs-related GIB, especially in the upper gastrointestinal tract. The protective effect was even stronger in patients using dabigatran than in those using Xa inhibitors (rivaroxaban and apixaban).

Drug-drug interactions in atrial fibrillation patients receiving direct oral anticoagulants

Polypharmacy is common in patients with atrial fibrillation (AF), making these patients vulnerable to the occurrence of potential drug-drug interactions (DDIs). We assessed the risk of ischemic stroke and major bleeding in the context of concomitant treatment with potential DDIs in patients with AF prescribed direct oral anticoagulants (DOACs). Using the common data model (CDM) based on an electronic health record (EHR) database, we included new users of DOACs from among patients treated for AF between January 2014 and December 2017 (n = 1938). The median age was 72 years, and 61.8% of the patients were males, with 28.2% of the patients having a CHA₂DS₂-VASc score in category 0–1, 49.4% in category 2–3, and 22.4% in category ≥ 4. The CHA₂DS₂-VASc score was significantly associated with ischemic stroke occurrence and hospitalization for major bleeding. Multiple logistic regression analysis showed that increased risk of ischemic stroke and hospitalization for major bleeding was associated with the number of DDIs regardless of comorbidities: ≥ 2 DDIs was associated with ischemic stroke (OR = 18.68; 95% CI, 6.22–55.27, P < 0.001) and hospitalization for major bleeding (OR = 5.01; 95% CI, 1.11–16.62, P < 0.001). DDIs can cause reduced antithrombotic efficacy or increased risk of bleeding in AF patients prescribed DOACs.

Risk of Gastrointestinal Bleeding on Treatment With Statin Alone or With Concomitant Administration of Warfarin: A Systematic Review and Meta-analysis of 5.3 Million Participants

OBJECTIVE

This study aimed to comprehensively evaluate the risk of gastrointestinal bleeding (GIB) with statin monotherapy or with concomitant warfarin use.

DATA SOURCES

PubMed, Web of Science, and EMBASE (via Scopus) were searched for observational studies that reported the risk of GIB in adults on statin therapy or with concomitant warfarin use until August 28, 2021.

STUDY SELECTION AND DATA EXTRACTION

Observational studies evaluating the risk of GIB in adults (age >18 years) on statin medication or concomitant use with warfarin were included.

DATA SYNTHESIS

In all, 14 studies with a total of 5 235 123 participants, reporting 48 677 GIB events (43 734 from statin users and 4943 from users of statin combined with warfarin), were included in the analyses. The pooled analysis revealed no difference in the risk of GIB with statin monotherapy (relative risk [RR]: 0.65; 95% CI: 0.42-1.02) or concomitant statin + warfarin use (RR: 0.97; 95% CI: 0.91-1.02). Prior use of statin was not associated with GIB risk (RR: 0.88; 95% CI: 0.63-1.22), whereas a shorter duration of statin use (<5 years) was associated with a lower risk of GIB (RR: 0.42; 95% CI: 0.18-0.97).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This analysis provides strong evidence on the association between statin use (with/without warfarin) and risk of GIB.

CONCLUSION

Statin alone or combined with warfarin was not significantly associated with either an increased or decreased risk of GIB. The GIB risk was significantly lower when statins were used for a short duration (<5 years). The putative relationship between statins and GIB in warfarin users warrant further investigation.