Comparative Pharmacokinetics of Vitamin K Antagonists

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.

The effect of administering preprocedural VITamin K on the international normalized ratio in patients anticoagulated with ACEnocoumarol (VITKACE-study): a prospective cohort study

BACKGROUND

The effect of the vitamin K antagonist acenocoumarol on coagulation needs to be reversed when patients undergo an invasive procedure with considerable bleeding risk. A strategy to achieve this is by administering oral vitamin K before a procedure while continuing acenocoumarol.

OBJECTIVES

To assess the effect on periprocedural international normalized ratio (INR) values and safety using oral vitamin K as anticoagulant reversal method.

METHODS

In this prospective cohort study, consecutive patients using acenocoumarol undergoing elective procedures between 2019 and 2022 were included. According to standard of care in our hospital, patients took 10 mg oral vitamin K 36 to 48 hours before the procedure while continuing their normal use of acenocoumarol. Effectiveness to lower INR to <1.8 preprocedural was assessed. Bleeding and thrombotic complications within 30 days after the procedure were assessed. Periprocedural course of INR was monitored by collecting additional blood samples.

RESULTS

Seventy-four patients were included for analysis. On the day of the procedure, an adequate INR of <1.8 was achieved in 99% of patients. One clinically relevant nonmajor bleeding complication and no thrombotic complications were observed during the first 30 days after the procedure. INR gradually restored to therapeutic level during the days after the procedure.

CONCLUSION

Using oral vitamin K while patients continue acenocoumarol intake is an effective way to adequately lower INR before an invasive procedure. Low amount of bleeding complications and absence of thromboembolic complications suggest that this is a safe strategy. The INR values returned gradually to therapeutic range after the procedure, probably contributing to the observed low bleeding rate.

Warfarin-A natural anticoagulant: A review of research trends for precision medication

BACKGROUND

Warfarin is a widely prescribed anticoagulant in the clinic. It has a more considerable individual variability, and many factors affect its variability. Mathematical models can quantify the quantitative impact of these factors on individual variability.

PURPOSE

The aim is to comprehensively analyze the advanced warfarin dosing algorithm based on pharmacometrics and machine learning models of personalized warfarin dosage.

METHODS

A bibliometric analysis of the literature retrieved from PubMed and Scopus was performed using VOSviewer. The relevant literature that reported the precise dosage of warfarin calculation was retrieved from the database. The multiple linear regression (MLR) algorithm was excluded because a recent systematic review that mainly reviewed this algorithm has been reported. The following terms of quantitative systems pharmacology, mechanistic model, physiologically based pharmacokinetic model, artificial intelligence, machine learning, pharmacokinetic, pharmacodynamic, pharmacokinetics, pharmacodynamics, and warfarin were added as MeSH Terms or appearing in Title/Abstract into query box of PubMed, then humans and English as filter were added to retrieve the literature.

RESULTS

Bibliometric analysis revealed important co-occuring MeShH and index keywords. Further, the United States, China, and the United Kingdom were among the top countries contributing in this domain. Some studies have established personalized warfarin dosage models using pharmacometrics and machine learning-based algorithms. There were 54 related studies, including 14 pharmacometric models, 31 artificial intelligence models, and 9 model evaluations. Each model has its advantages and disadvantages. The pharmacometric model contains biological or pharmacological mechanisms in structure. The process of pharmacometric model development is very time- and labor-intensive. Machine learning is a purely data-driven approach; its parameters are more mathematical and have less biological interpretation. However, it is faster, more efficient, and less time-consuming. Most published models of machine learning algorithms were established based on cross-sectional data sourced from the database.

CONCLUSION

Future research on personalized warfarin medication should focus on combining the advantages of machine learning and pharmacometrics algorithms to establish a more robust warfarin dosage algorithm. Randomized controlled trials should be performed to evaluate the established algorithm of warfarin dosage. Moreover, a more user-friendly and accessible warfarin precision medicine platform should be developed.

Genetic polymorphisms and major bleeding risk during vitamin K antagonists treatment: The BLEEDS case-cohort

BACKGROUND

Major bleeding occurs annually in 1%-3% of patients on vitamin K antagonists (VKAs), despite close monitoring. Genetic variants in proteins involved in VKA response may affect this risk.

AIM

To determine the association of genetic variants (cytochrome P450 enzymes 2C9 [CYP2C9] and 4F2 [CYP4F2], gamma-glutamyl carboxylase [GGCX]) with major bleeding in VKA users, separately and combined, including vitamin K epoxide reductase complex subunit-1 (VKORC1).

METHODS

A case-cohort study was established within the BLEEDS cohort, which includes 16,570 patients who initiated VKAs between 2012 and 2014. We selected all 326 major bleeding cases that occurred during 17,613 years of follow-up and a random subcohort of 978 patients. We determined variants in CYP2C9, CYP4F2, GGCX, VKORC1 and evaluated the interaction between variant genotypes. Hazard ratios for major bleeding with 95% confidence intervals (95% CI) were estimated by weighted Cox regression.

RESULTS

Genotype was determined in 256 cases and 783 subcohort members. Phenprocoumon was the most prescribed VKA for both cases and the subcohort (78% and 75%, respectively). Patients with major bleeding were slightly older than subcohort patients. CYP4F2-TT carriership was associated with a 1.6-fold (95% CI 0.9-2.8) increased risk of major bleeding compared with CC-alleles, albeit not statistically significant. For the CYP2C9 and GGCX variants instead, the major bleeding risk was around unity. Carrying at least two variant genotypes in CYP2C9 (poor metabolizer), CYP4F2-TT, and VKORC1-AA was associated with a 4.0-fold (95%CI 1.4-11.4) increased risk, while carriers of both CYP4F2-TT and VKORC1-AA had a particularly increased major bleeding risk (hazard ratio 6.7, 95% CI 1.5-29.8) compared with carriers of CC alleles in CYP4F2 and GG in VKORC1. However, the number of major bleeding cases in carriers of multiple variants was few (8 and 5 patients, respectively).

CONCLUSIONS

CYP4F2 polymorphism was associated with major bleeding, especially in combination with VKORC1 genetic variants. These variants could be considered to further personalize anticoagulant treatment.

Interaction of the lysozyme with anticoagulant drug warfarin: Spectroscopic and computational analyses

Warfarin is a cardiovascular drug, used to treat or inhibit the coagulation of the blood. In this paper, we have studied the interaction of lysozyme with warfarin using several experimental (fluorescence, UV-visible and circular dichroism spectroscopies) and computational (molecular docking, molecular dynamics and DFT) approaches. Experimental studies have suggested that there was a strong interaction between lysozyme and warfarin. Inner filter effect played important role in fluorescence experimental data which show that the emission intensity of lysozyme decreased on the addition of warfarin, however, after inner filter effect correction the actual outcome turned out be the fluorescence enhancement. The extent of binding, increased with temperature rise. The interaction was primarily taken place via the dominance of hydrophobic forces. Small amount of warfarin didn't influence the secondary structure of lysozyme; however, the higher concentration of warfarin caused a decrease in the helicity of the protein and a consequent partial unfolding. Molecular docking studies were also performed which revealed that warfarin binds with lysozyme mainly with hydrophobic forces along with a significant contribution of hydrogen bonding. The flexibility of warfarin played important role in fitting the molecule into the binding pocket of lysozyme. Frontier molecular orbitals of warfarin, using DFT, in free as well as complexed form have also been calculated and discussed. Molecular dynamics simulations of unbound and warfarin bound lysozyme reveal a stable complex with slightly higher RMSD values in the presence of warfarin. Despite slightly increased RMSF values, the overall compactness and folding properties remain consistent, emphasizing strong binding towards lysozyme through the results obtained from intermolecular hydrogen bonding analysis. Essential dynamics analysis suggests warfarin induces slight structural changes without significantly altering the conformation, additionally supported by SASA patterns. Aside from the examination of global and essential motion, the MM/PBSA-based analysis of binding free energy elucidates the significant binding of warfarin to lysozyme, indicating a binding free energy of -13.3471 kcal/mol.

Impact of renal function variability on long-term prognosis in ischemic stroke patients with atrial fibrillation

Background

Although renal dysfunction is associated with adverse clinical outcomes in patients with atrial fibrillation (AF) following stroke, the impact of renal function variability is unclear.

Aim

This study aimed to assess the association between renal function variability and various adverse clinical outcomes in patients with transient ischemic attack (TIA)/ischemic stroke and atrial fibrillation (AF).

Methods

We conducted a population-based study and retrospectively identified patients hospitalized with a diagnosis of TIA/ischemic stroke and AF during 2016-2020 using the Clinical Data Analysis and Reporting System of Hong Kong. Serial serum creatinine tested upon the onset of TIA/ischemic stroke and during their subsequent follow-up was collected. Renal function variability was calculated using the coefficient of variation of the estimated glomerular filtration rate (eGFR). Clinical endpoints that occurred during the study period were captured and included ischemic stroke/systemic embolism, intracerebral hemorrhage (ICH), total bleeding, major adverse cardiovascular events (MACE), cardiovascular, non-cardiovascular, and all-cause mortality. Competing risk regression and Cox proportional hazard regression models were used to assess the associations of renal function variability with the outcomes of interest.

Results

A total of 3,809 patients (mean age 80 ± 10 years, 43% men) who satisfied the inclusion and exclusion criteria were followed up for a mean of 2.5 ± 1.5 years (9,523 patient-years). The mean eGFR was 66 ± 22 mL/min/1.73 m2 at baseline, and the median number of renal function tests per patient during the follow-up period was 20 (interquartile range 11-35). After accounting for potential confounders, a greater eGFR variability was associated with increased risks of recurrent ischemic stroke/systemic embolism [fully adjusted subdistribution hazard ratio 1.11, 95% confidence interval (CI) 1.03-1.20], ICH (1.17, 1.01-1.36), total bleeding (1.13, 1.06-1.21), MACE (1.22, 1.15-1.30), cardiovascular (1.49, 1.32-1.69), non-cardiovascular (1.43, 1.35-1.52), and all-cause mortality (fully adjusted hazard ratio 1.44, 1.39-1.50).

Conclusion

Visit-to-visit renal function variability is independently associated with adverse clinical outcomes in TIA/ischemic stroke patients with AF. Further large-scale studies are needed to validate our results.

Drug-drug interactions with oral anticoagulants: information consistency assessment of three commonly used online drug interactions databases in Switzerland

Background: Toxicity or treatment failure related to drug-drug interactions (DDIs) are known to significantly affect morbidity and hospitalization rates. Despite the availability of numerous databases for DDIs identification and management, their information often differs. Oral anticoagulants are deemed at risk of DDIs and a leading cause of adverse drug events, most of which being preventable. Although many databases include DDIs involving anticoagulants, none are specialized in them. Aim and method: This study aims to compare the DDIs information content of four direct oral anticoagulants and two vitamin K antagonists in three major DDI databases used in Switzerland: Lexi-Interact, Pharmavista, and MediQ. It evaluates the consistency of DDIs information in terms of differences in severity rating systems, mechanism of interaction, extraction and documentation processes and transparency. Results: This study revealed 2'496 DDIs for the six anticoagulants, with discrepant risk classifications. Only 13.2% of DDIs were common to all three databases. Overall concordance in risk classification (high, moderate, and low risk) was slight (Fleiss' kappa = 0.131), while high-risk DDIs demonstrated a fair agreement (Fleiss' kappa = 0.398). The nature and the mechanism of the DDIs were more consistent across databases. Qualitative assessments highlighted differences in the documentation process and transparency, and similarities for availability of risk classification and references. Discussion: This study highlights the discrepancies between three commonly used DDI databases and the inconsistency in how terminology is standardised and incorporated when classifying these DDIs. It also highlights the need for the creation of specialised tools for anticoagulant-related interactions.

Isocyanide-based multicomponent reactions for the synthesis of benzopyran derivatives with biological scaffolds

Benzopyrans (BZPs) are among the most privileged and influential small O-heterocycles that form the core of many natural compounds, commercial drugs, biological compositions, agrochemicals, and functional materials. BZPs are divided into six general categories including coumarins, chromans, 2H-chromenes, 4H-chromenes, chromones, and 4-chromanones, each of which is abundant in many plants and foods. These oxygenated heterocyclic compounds are fascinating motifs and have extensive applications in biology and materials science. Hence, numerous efforts have been made to develop innovative approaches for their extraction and synthesis. However, most of them are step-by-step or multi-step strategies that suffer from waste material generation and a tedious extraction process. Isocyanide-based multicomponent reactions (I-MCRs) offer a highly efficient method for overcoming these problems. The I-MCR is a simple and environmentally friendly one-pot domino procedure that does not require intermediate isolation or workup and is generally more efficient in material usage. This review covers all research articles related to I-MCRs for synthesizing BZP derivatives from the beginning to the middle of the year 2023. This strategy will be useful for organic and pharmaceutical chemists to design new drugs and optimize the synthesis steps of biological compounds and commercial drugs with benzopyran cores.

Design of a structure-activity relationship model of vitamin K epoxide reductase (VKORC1) inhibitors combining chemical synthesis of new compounds, enzymatic assays and molecular modelling

Vitamin K antagonists (VKAs) anticoagulants have been used since the 1950s as medicines and rodenticides. These molecules are mainly 4-hydroxycoumarin derivatives and act by inhibiting the vitamin K epoxide reductase (VKORC1), an endoplasmic reticulum membrane resident enzyme. However, many VKORC1 mutations have been reported over the last decade, inducing VKAs resistances and thus treatments failures. Although studies have reported experimental and computational investigations of VKAs based on VKORC1 structural homology models, the development of new effective anticoagulants has been quite complex due to the lack of structural data and reliable structure-activity relationships. However, the recent publication of VKORC1 crystal structure provides new information for further studies. Based on these findings, we combined chemical synthesis, enzymatic assays and molecular modelling methods to design a structure-activity relationship (SAR) model. Our results proved that the lipophilicity, the membrane permeability of inhibitors and their affinity towards human VKORC1 enzyme are the main characteristics for potent anticoagulants. Our SAR model managed to rank compounds according to their ability to inhibit the human VKORC1. Such a tool might constitute an alternative to evaluate new molecules potency before their chemical synthesis and biological assessment and might assist the development of new VKAs.

Comparison of phenprocoumon with direct oral anticoagulants in catheter ablation of atrial fibrillation

Aims

In patients undergoing catheter ablation for atrial fibrillation (AF), direct oral anticoagulants (DOACs) are as effective and safe as the vitamin K antagonist (VKA) warfarin. Phenprocoumon has a different pharmacokinetic profile compared with warfarin and is the most used VKA in Germany. The aim of the study was to compare DOAC with phenprocoumon.

Methods and results

In this retrospective single-centre cohort study, 1735 patients who underwent 2219 consecutive catheter ablations for AF between January 2011 and May 2017 were included. All patients were in-hospital for at least 48 h after catheter ablation. The primary outcome was defined as peri-procedural thrombo-embolic events. The secondary outcome was any bleeding according to the International Society on Thrombosis and Haemostasis (ISTH). The mean age of the patients was 63.3 years. Phenprocoumon was prescribed in 929 (42%) of the cases, and in 697 (31%) dabigatran, 399 (18%) rivaroxaban, and 194 (9%) apixaban. During hospitalization, 37 (1.6%) thrombo-embolic events occurred, including 23 transient ischaemic attacks (TIAs). Compared with the use of phenoprocoumon, the use of DOAC was significantly associated with a lower thrombo-embolic risk [16 (1.2%) vs. 21 (2.2%), odds ratio (OR)], 0.5 [95% confidence interval (CI) 0.2-0.9], P = 0.04. No statistically significant association with bleeding risk was observed [phenprocomoun: 122 (13%); DOAC: 163 (12.6%); OR 0.9 (95% CI 0.7-1.2); P = 0.70]. Interruption of oral anticoagulation (OAC) was associated with an increased risk for thrombo-embolic complications [OR 2.2 (1.1-4.3); P = 0.031], and bleeding [OR 2.5 (95% CI 1.8-3.2), P = 0.001].

Conclusion

In patients undergoing catheter ablation for AF, the use of DOAC was associated with a reduced risk of thrombo-embolic events compared with phenprocoumon. Non-interrupted oral anticoagulation (OAC) therapy was associated with a reduced risk of peri-procedural thrombo-embolic and any bleeding complications.

Exploring the potential impact of probiotic use on drug metabolism and efficacy

Probiotics are frequently consumed as functional food and widely used as dietary supplements, but are also recommended in treating or preventing various gastrointestinal diseases. Therefore, their co-administration with other drugs is sometimes unavoidable or even compulsory. Recent technological developments in the pharmaceutical industry permitted the development of novel drug-delivery systems for probiotics, allowing their addition to the therapy of severely ill patients. Literature data regarding the changes that probiotics could impose on the efficacy or safety of chronic medication is scarce. In this context, the present paper aims to review probiotics currently recommended by the international medical community, to evaluate the relationship between gut microbiota and various pathologies with high impact worldwide and, most importantly, to assess the literature reports concerning the ability of probiotics to influence the pharmacokinetics/pharmacodynamics of some widely used drugs, especially for those with narrow therapeutic indexes. A better understanding of the potential influence of probiotics on drug metabolism, efficacy and safety could contribute to improving therapy management, facilitating individualized therapy and updating treatment guidelines.

A Physiological-Based Pharmacokinetic Model Embedded with a Target-Mediated Drug Disposition Mechanism Can Characterize Single-Dose Warfarin Pharmacokinetic Profiles in Subjects with Various CYP2C9 Genotypes under Different Cotreatments

Warfarin, a commonly prescribed oral anticoagulant medication, is highly effective in treating deep vein thrombosis and pulmonary embolism. However, the clinical dosing of warfarin is complicated by high interindividual variability in drug exposure and response and its narrow therapeutic index. CYP2C9 genetic polymorphism and drug-drug interactions (DDIs) are substantial contributors to this high variability of warfarin pharmacokinetics (PK), among numerous factors. Building a physiology-based pharmacokinetic (PBPK) model for warfarin is not only critical for a mechanistic characterization of warfarin PK but also useful for investigating the complicated dose-exposure relationship of warfarin. Thus, the objective of this study was to develop a PBPK model for warfarin that integrates information regarding CYP2C9 genetic polymorphisms and their impact on DDIs. Generic PBPK models for both S- and R-warfarin, the two enantiomers of warfarin, were constructed in R with the mrgsolve package. As expected, a generic PBPK model structure did not adequately characterize the warfarin PK profile collected up to 15 days following the administration of a single oral dose of warfarin, especially for S-warfarin. However, following the integration of an empirical target-mediated drug disposition (TMDD) component, the PBPK-TMDD model well characterized the PK profiles collected for both S- and R-warfarin in subjects with different CYP2C9 genotypes. Following the integration of enzyme inhibition and induction effects, the PBPK-TMDD model also characterized the PK profiles of both S- and R-warfarin in various DDI settings. The developed mathematic framework may be useful in building algorithms to better inform the clinical dosing of warfarin. SIGNIFICANCE STATEMENT: The present study found that a traditional physiology-based pharmacokinetic (PBPK) model cannot sufficiently characterize the pharmacokinetic profiles of warfarin enantiomers when warfarin is administered as a single dose, but a PBPK model with a target-mediated drug disposition mechanism can. After incorporating CYP2C9 genotypes and drug-drug interaction information, the developed model is anticipated to facilitate the understanding of warfarin disposition in subjects with different CYP2C9 genotypes in the absence and presence of both cytochrome P450 inhibitors and cytochrome P450 inducers.

Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients

The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.

Selective Serotonin Reuptake Inhibitor Use and Risk of Major Bleeding during Treatment with Vitamin K Antagonists: Results of A Cohort Study

BACKGROUND

 Selective serotonin reuptake inhibitors (SSRIs) may increase the risk of major bleeding by decreasing platelet function or decreasing vitamin K antagonist (VKA) metabolism via cytochrome P450 (CYP) inhibition.

AIMS

 To determine whether SSRIs are associated with major bleeding during VKA treatment and investigate the possible mechanisms.

METHODS

 In this cohort study, information on SSRI use and bleeding complications was obtained from patient records of VKA initiators between 2006 and 2018 from two anticoagulation clinics. Conditional logistic regression and time-dependent Cox regression were used to estimate the effect of SSRIs on a high international normalized ratio (INR ≥ 5) within 2 months after SSRI initiation and on major bleeding during the entire period of SSRI use, respectively. SSRI use was stratified for (non-)CYP2C9 inhibitors.

RESULTS

 A total of 58,918 patients were included, of whom 1,504 were SSRI users. SSRI initiation versus nonuse was associated with a 2.41-fold (95% confidence interval [CI]: 2.01-2.89) increased risk for a high INR, which was 3.14-fold (95% CI: 1.33-7.43) among CYP2C9-inhibiting SSRI users. The adjusted hazard ratio of major bleeding was 1.22 (95% CI: 0.99-1.50) in all SSRI users and 1.31 (95% CI: 0.62-2.72) in CYP2C9-inhibiting SSRI users compared with nonusers.

CONCLUSION

 SSRI use is associated with an increased risk of high INR and might be associated with major bleeding. The risk of a high INR was slightly more elevated for CYP2C9-inhibiting SSRI users, suggesting there might be a pharmacokinetic interaction (by CYP2C9 inhibition) next to a pharmacodynamic effect of SSRIs on platelet activation.

Gerinnungsmanagement in der schweren, fortgeschrittenen Niereninsuffizienz

Patienten mit chronischer Niereninsuffizienz (CKD) haben ein hohes Risiko für nicht valvuläres Vorhofflimmern (NVAF) und häufig ein höheres Risiko für venöse Thromboembolien (VTE) aufgrund ihrer Grunderkrankungen wie z. B. Diabetes. Bisher kamen Vitamin-K-Antagonisten (VKA) auch bei diesen Patienten in Deutschland zum Einsatz. VKA haben ein erhöhtes Blutungsrisiko und werden als Risikofaktor für eine Verschlechterung der Nierenfunktion und/oder Gefäßsituation (Athero- und Mediasklerose) von Patienten diskutiert. Aus diesen Gründen und den vorliegenden Studiendaten werden deshalb direkt wirkende orale Antikoagulanzien (DOAC) auch bei Patienten mit NVAF und CKD (G1–G3) in den Leitlinien empfohlen. Allerdings kann keine klare Empfehlung für den Einsatz von DOAC bei Dialysepatienten gegeben werden. Heparine spielen in diesem Zusammenhang nur eine untergeordnete Rolle.

Pharmacokinetics of Phenprocoumon in Emergency Situations-Results of the Prospective Observational RADOA-Registry (Reversal Agent Use in Patients Treated with Direct Oral Anticoagulants or Vitamin K Antagonists Registry)

Background: Phenprocoumon has been used as an oral anticoagulant in patients with thromboembolic disease for more than 40 years. So far its pharmacokinetics have not been analyzed in emergency situations. Methods: Phenprocoumon-treated patients with major bleeding or urgent surgery were included in a prospective, observational registry. Phenprocoumon drug concentrations were analyzed in samples, collected as part of routine care using ultraperformance liquid chromatography tandem mass spectrometry. Moreover, anticoagulant intensity and drug half-life (t1/2) were calculated. Results: 115 patients were included. Phenprocoumon levels declined over time with a half-life of 5.27 and 5.29 days in patients with major bleedings (n = 82) and with urgent surgery (n = 33). Baseline phenprocoumon levels were 2.2 times higher in the bleeding group compared to the surgery group (1.92 vs. 0.87 ng/mL, p < 0.0001). International normalized ratio (INR) values decreased rapidly during the first 24 h. In 27.6% of patients a rebound of INR (recurrent increase > 1.5) was observed which was associated with significantly increased bleeding rates (22% vs. 4.2% in patients with or without INR rebound, p = 0.012). Conclusions: In emergency situations, the long half-life of phenprocoumon may cause INR rebound and associated recurrent bleedings. Optimal management may need to include repeated vitamin K supplementation over days.

Frequency of Hemorrhagic Side Effects of Botulinum Neurotoxin Treatment in Patients with Blepharospasm and Hemifacial Spasm on Antithrombotic Medication

The aim of this study was to investigate the frequency of hemorrhagic side effects of botulinum neurotoxin A injections (BoNT/A) for the treatment of benign essential blepharospasm (BEB) and hemifacial spasm (HFS) in patients taking antithrombotic drugs (ATD). A total of 140 patients were included (female: 65%; BEB: 75%; mean age: 70 ± 12 years). According to their current antithrombotic medication, participants were either assigned to the ATD group (41%), or to the control group (59%). The ATD group was further divided into subgroups depending on the medication administered: acetylsalicylic acid, ADP receptor antagonists, direct oral anticoagulants, vitamin-K antagonists, or dual antiplatelet therapy. The frequency of hemorrhagic side effects was recorded by retrospective analysis of past treatments as documented in the patient's file set in relation to the number of past treatments (hematoma frequency of past treatments, HF_retro) as well as by a prospective survey capturing the side effects of one single treatment (hematoma frequency of actual treatment, HF_actual). There was no significant difference in hematoma frequency between the ATD group and the control group, neither for past (HF_retro: ATD: 2%; 45/2554; control: 4%; 109/2744) nor for the current BoNT/A treatments (HF_actual: ATD: 30%; 16/53; control: 31%; 22/72). Even between ATD subgroups, hematoma frequency did not differ significantly. Overall, hemorrhagic side effects of the BoNT/A treatment for BEB and HFS were mild and non-disabling.

Perioperative Management of Antithrombotic Therapy: An American College of Chest Physicians Clinical Practice Guideline

BACKGROUND

The American College of Chest Physicians Clinical Practice Guideline on the Perioperative Management of Antithrombotic Therapy addresses 43 Patients-Interventions-Comparators-Outcomes (PICO) questions related to the perioperative management of patients who are receiving long-term oral anticoagulant or antiplatelet therapy and require an elective surgery/procedure. This guideline is separated into four broad categories, encompassing the management of patients who are receiving: (1) a vitamin K antagonist (VKA), mainly warfarin; (2) if receiving a VKA, the use of perioperative heparin bridging, typically with a low-molecular-weight heparin; (3) a direct oral anticoagulant (DOAC); and (4) an antiplatelet drug.

METHODS

Strong or conditional practice recommendations are generated based on high, moderate, low, and very low certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology for clinical practice guidelines.

RESULTS

A multidisciplinary panel generated 44 guideline recommendations for the perioperative management of VKAs, heparin bridging, DOACs, and antiplatelet drugs, of which two are strong recommendations: (1) against the use of heparin bridging in patients with atrial fibrillation; and (2) continuation of VKA therapy in patients having a pacemaker or internal cardiac defibrillator implantation. There are separate recommendations on the perioperative management of patients who are undergoing minor procedures, comprising dental, dermatologic, ophthalmologic, pacemaker/internal cardiac defibrillator implantation, and GI (endoscopic) procedures.

CONCLUSIONS

Substantial new evidence has emerged since the 2012 iteration of these guidelines, especially to inform best practices for the perioperative management of patients who are receiving a VKA and may require heparin bridging, for the perioperative management of patients who are receiving a DOAC, and for patients who are receiving one or more antiplatelet drugs. Despite this new knowledge, uncertainty remains as to best practices for the majority of perioperative management questions.

Warfarin resistance: possibilities to solve this problem. A case report

Effective prevention of thromboembolism is essential for patients with mechanical prosthetic heart valves. For this group of patients, vitamin K antagonists (VKAs) remain the drug group of choice despite the widespread use of new anticoagulants in other diseases. As a consequence, warfarin resistance remains a serious challenge for physicians. The current report describes a 65-year-old male patient that had a mechanical prosthetic aortic valve implanted due to severe aortic insufficiency after infective endocarditis. Despite consistent increases in his warfarin dose, the level of international normalized ratio (INR) remained very low. The patient was considered to have warfarin resistance. Warfarin was successfully replaced by another VKA, acenocoumarol, which resulted in a stable INR observed over 1 year of follow-up. Achieving the target INR in patients with mechanical prosthetic heart valves using VKAs is the main goal of thromboprophylaxis. Although the genetic changes that cause warfarin resistance are understood, the options to overcome these pharmacogenetic issues remain limited. Based on the success with this current patient, physicians with similar patients with warfarin resistance might wish to consider replacing warfarin with acenocoumarol.

Pharmacogenetic variants influence vitamin K anticoagulant dosing in patients with mechanical prosthetic heart valves

Background: Vitamin K antagonists (VKAs) are class I oral anticoagulants that are widely prescribed following surgical heart valve implantation. The objective of this study was to quantify the relative effects of VKORC1, CYP2C9 and CYP4F2 genotypes in predicting VKA dosing. Materials & methods: A total of 506 South Indian patients with mechanical prosthetic heart valves who were prescribed oral VKAs, such as warfarin or acenocoumarol, were genotyped. The discriminatory ability of mutant genotypes to predict dose categories and bleeding events was assessed using regression analysis. Results: The VKORC1 rs9923231, CYP2C9*3 and CYP4F2*3 mutant genotypes significantly influenced VKA-dose requirements and explained 27.47% of the observed dose variation. Conclusion: These results support pharmacogenetic screening for initial VKA dosing among South Indian patients with mechanical prosthetic heart valves.

[Safety and effectiveness of oral anticoagulation in patients with atrial fibrillation and renal insufficiency - a real-world perspective]

Non-vitamin-K dependent oral anti-coagulants (NOAC) are the current therapeutic standard for preventing strokes in patients with atrial fibrillation (AF) and should be preferred over vitamin K antagonists (VKA) in this indication. This recommendation applies also to patients with VHF and concomitant chronic kidney disease (CKD). Real World Evidence (RWE), i. e., structured data from clinical practice, extends and confirms the clinical evidence generated in more formalized clinical trials with NOAC and VKA. In addition, RWE in respect to the indication showed that the superiority of NOAC versus the VKA warfarin can also be extrapolated to phenprocoumon, the commonly used VKA in Germany. Furthermore, data include evidence that the typical progression of CKD appears to be less pronounced in individuals treated with NOAC compared to those treated with VKA.

Development of a Fluorescent Microfluidic Device Based on Antibody Microarray Read-Out for Therapeutic Drug Monitoring of Acenocoumarol

The development of a proof-of-concept point-of-care (PoC) device for the determination of oral anticoagulants determination is presented. Acenocoumarol (ACL) is prescribed to prevent certain cardiovascular diseases related to the prevention of deep vein thrombosis, pulmonary embolism, myocardial infarction, and stroke. Oral anticoagualant treatment (OAT) represents a population of 2% under treatment which has expenditures about $ 144 million in 2011. The main drawback for OAT is the associated narrow therapeutic window and the unpredictable dose-response relationship, which is one of the main causes for visiting the emergency room at the hospitals. In a previous work, family antibodies were produced for the simultaneous detection of ACL and warfarin (W) depending on the area of application. It was developed in different formats, indirect and direct, either with similar detectabilities and both assays quantifying the oral anticoagulants with high accuracy and reproducibility. We present the implementation of the already developed immunochemical method to a point-of-care (PoC) device to assist on the patient compliance assessment programs. In order to achieve this goal, a first development was performed implementing ACL ELISA assay into a microarray format with fluorescent read-out. The assay was successfully implemented achieving a LOD of 1.23 nM of ACL directly measured in human plasma. Then, a fully integrated microfluidic system is developed which incorporates the specific immunoreagents for the detection of ACL. The immunoreagents were attached onto the glass slide in a microarray format. The system is automatic, rapid, sensitive, and disposable that could help clinicians monitor patients under OAT. According to the fluorescent label of the ACL binding, the chip can be easily read with a scanner. The microfluidic system performed good according to the robust and reproducible signals, and subsequently yielded an accurate result.

The Immediate Effect of COVID-19 Vaccination on Anticoagulation Control in Patients Using Vitamin K Antagonists

Background  In January 2021, the Dutch vaccination program against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was started. Clinical studies have shown that systemic reactions occur in up to 50% of vaccine recipients. Therefore, COVID-19 vaccination could affect anticoagulation control, potentially leading to an increased risk of thrombotic events and bleeding complications.

Aims  This article investigates whether the BNT162b2 vaccine affects anticoagulation control in outpatients using vitamin K antagonists (VKAs).

Methods  A case-crossover study was performed in a cohort of outpatient VKA users from four Dutch anticoagulation clinics who received a BNT162b2 vaccine. International normalized ratio (INR) results and VKA dosages before the first vaccination, the reference period, were compared with those after the first and second vaccination.

Results  A total of 3,148 outpatient VKA users were included, with a mean age (standard deviation) of 86.7 (8.7) years, of whom 43.8% were male, 67.0% used acenocoumarol, and 33.0% phenprocoumon. We observed a decrease of 8.9% of INRs within range in the standard intensity group (target INR 2.0–3.0). There was both an increased risk of supratherapeutic (odds ratio [OR] = 1.34 [95% confidence interval [CI] 1.08–1.67]) and subtherapeutic levels (OR = 1.40 [95% CI 1.08–1.83]) after first vaccination. In the high-intensity group (target INR 2.5–3.5), the risk of a supratherapeutic INR was 2.3 times higher after first vaccination (OR = 2.29 [95% CI 1.22–4.28]) and 3.3 times higher after second vaccination (OR = 3.25 [95% CI 1.06–9.97]).

Conclusion  BNT162b2 was associated with an immediate negative effect on anticoagulation control in patients treated with VKAs, so it is advisable to monitor the INR shortly after vaccination, even in stable patients.

The value and limitations of new oral anticoagulant plasma level assessments

The class of new oral anticoagulants (NOACs) has been developed to provide reliable oral anticoagulation without the need for therapeutic drug monitoring. Based on phase I and II trials and pharmacokinetic and pharmacodynamic modeling, fixed drug doses have been selected for large phase III clinical trials for each currently available NOAC. In these trials, the use of the fixed dose without plasma level assessments was shown to be at least as effective and at least as safe as vitamin K antagonists with continuous therapeutic drug monitoring. Real world evidence reaffirms that the use of a fixed NOAC dose without plasma level assessment is safe and effective in a large variety of patients. Nevertheless, measurement of NOAC plasma levels can add information that may be useful in some clinical scenarios. This review discusses the possible use cases, the limitations, and the practical implementation of measuring NOAC plasma concentrations.

Anti-embolic and anti-oxidative effects of a novel (E)-4-amino-N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide against isoproterenol and vitamin-K induced ischemic stroke

This study aimed to evaluate the cerebroprotective potential of a novel synthetic coumarin, (E)-4-amino-N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl)ethylidene) benzohydrazide noted (HC) against a pharmaceutically induced ischemic stroke in experimental male Wistar rats. Animals were randomly allocated into four groups: control, Stroke, Stroke + Ace (acenocoumarol) and Stroke + HC-treated group for 7 days. Our results showed that stroke group evidenced atrial flutter, significant cardiac hypertrophy (+23%) and increase in plasma level of troponin-T, with disturbance in plasma ionic levels and rise in fibrinogen rate and oxidative damages in heart and brain. Moreover, the histological findings revealed myocardium necrosis, cardiac cavity thrombi and brain injury as compared to normal rats. However, HC-treatment significantly prevents the embolic process, improves cerebral damages and mitigates the oxidative stress markers in stroke rats. Overall, HC is endowed with a thrombolytic potential against MI and stroke in such severe conditions through an anti-vit K (AVK) mechanism.

The influence of excessive consumption of liquorice on phenprocoumon (Marcumar®): a case report

Here, the case of a 92-year-old female patient, who was diagnosed with atrial fibrillation and treated with phenprocoumon (Marcumar®), is reported. Pre-existing comorbidities were arterial hypertension, coronary heart disease, diabetes mellitus type 2, mild senile dementia and renal insufficiency. Despite treatment with phenprocoumon (Marcumar®), the patient experienced an ischaemic stroke. Her measured international normalized ratio (INR)-values during the months before the stroke were within the therapeutic range of 2–3, then suddenly decreased to 1.25. A retrospective inquiry failed to identify any significant changes in behaviour or therapy adherence, other than the consumption of 1.5 kg (3.3 lb) of hard-boiled candy liquorice in the days leading up to the stroke. The sudden decrease in INR-values may be explained by the influence of liquorice and its compounds on the pharmacokinetics of phenprocoumon (Marcumar®). In this context, the most important factors are the susceptibility of vitamin K antagonists to nutrition or metabolic irregularities, the influence of liquorice on the function of isoenzymes of the cytochrome P450 family that may lead to reduced bioavailability of phenprocoumon, and the influence of liquorice on peroxisome proliferator-activated receptor alpha transactivation.

Anticoagulant rodenticide ingestion: Who will develop coagulopathy?

Introduction:

Development of coagulopathy after anticoagulant rodenticide ingestion varies among patients. This study aimed to identify factors that were associated with coagulopathy after anticoagulant rodenticide ingestion.

Methods:

This was a retrospective cohort study, conducted in the Hong Kong Poison Information Centre. All patients who reported rodenticide exposure and presented to the Accident and Emergency Department from 1 January 2010 to 31 December 2019 were recruited. Coagulopathy was defined as International Normalized Ratio of 1.3 or above.

Results:

One hundred sixty-nine patients were included in the final analysis. The median age was 44 years old. Forty-nine patients developed coagulopathy (International Normalized Ratio ⩾1.3). Univariate analysis (at p < 0.05) showed that age (p = 0.003), ingestion of first-generation anticoagulant rodenticide (p = 0.017), ingestion of more than one pack (p < 0.001), intentional ingestion (p = 0.002), hypoalbuminemia (p < 0.001), elevated alanine aminotransferase level (p = 0.041) and abnormal estimated glomerular filtration rate (p = 0.005) on presentation, and co-ingestion with paracetamol (p = 0.018) were associated with coagulopathy after anticoagulant rodenticide ingestion. Among these, ingestion of more than one pack (p < 0.001; odds ratio = 19.8; 95% confidence interval = 6.78–65.7), ingestion of first-generation anticoagulant rodenticide (p = 0.006; odds ratio = 5.2; 95% confidence interval = 1.96–15.2), hypoalbuminemia (p < 0.001; odds ratio = 22.4; 95% confidence interval = 6.17–99.0) and elevated alanine aminotransferase level on presentation (p = 0.039; odds ratio = 7.11; 95% confidence interval = 1.58–33.1) were statistically significant in the multivariate analysis.

Conclusion:

Ingestion of more than one pack and ingestion of first-generation anticoagulant rodenticides were significantly associated with the development of coagulopathy after anticoagulant rodenticide ingestion. Patients who developed hypoalbuminemia or elevated alanine aminotransferase level as a result of anticoagulant rodenticide ingestion were also significantly associated with the development of coagulopathy.

Biomodification of acenocoumarol by bifidobacteria

The increased interest of consumers in probiotic foods requires a deeper knowledge on the possible interactions with drugs, because their pharmacological properties could be modified. In this context, these studies are relevant for drugs such as acenocoumarol, whose dosage must be controlled due to, among other factors, food-drug interactions. Acenocoumarol is an oral anticoagulant with a narrow therapeutic range. The aim of the present research is to evaluate, in vitro, the effect of bifidobacteria on acenocoumarol. The drug was incubated with Bifidobacterium bifidum CIDCA 5310 or Bifidobacterium adolescentis CIDCA 5317 in MRS broth at 37°C for 24 h in anaerobic conditions. The effect of incubation with sterilized spent culture supernatants (SSCS) was also evaluated. Analysis by RP-HPLC showed that both bifidobacterial strains reduced the area of the acenocoumarol peak and two new peaks were evidenced. In addition, a decrease in the intensity of the bands at 1650, 1390 and 1110/cm was observed in the FTIR spectroscopic determinations. Moreover, a new band appeared at 1720/cm. No effect on the drug was observed when incubation was performed with SSCS. The present study showed a significant change in the concentration of the anticoagulant after incubation with bifidobacteria and results are compatible with biomodification of the drug due to enzymatic activity of bifidobacteria.

Natural Coumarins: Exploring the Pharmacological Complexity and Underlying Molecular Mechanisms

Coumarins belong to the benzopyrone family commonly found in many medicinal plants. Natural coumarins demonstrated a wide spectrum of pharmacological activities, including anti-inflammatory, anticoagulant, anticancer, antibacterial, antimalarial, casein kinase-2 (CK2) inhibitory, antifungal, antiviral, Alzheimer's disease inhibition, neuroprotective, anticonvulsant, phytoalexins, ulcerogenic, and antihypertensive. There are very few studies on the bioavailability of coumarins; therefore, further investigations are necessitated to study the bioavailability of different coumarins which already showed good biological activities in previous studies. On the evidence of varied pharmacological properties, the present work presents an overall review of the derivation, availability, and biological capacities of coumarins with further consideration of the essential mode of their therapeutic actions. In conclusion, a wide variety of coumarins are available, and their pharmacological activities are of current interest thanks to their synthetic accessibility and riches in medicinal plants. Coumarins perform the valuable function as therapeutic agents in a range of medical fields.

Effects of rivaroxaban and warfarin on the risk of gastrointestinal bleeding and intracranial hemorrhage in patients with atrial fibrillation: Systematic review and meta-analysis

To assess the risk of gastrointestinal bleeding and intracranial hemorrhage in patients with atrial fibrillation (AF) after the use of rivaroxaban or warfarin. To investigate the effects of rivaroxaban and warfarin on gastrointestinal and intracranial hemorrhage in patients with AF, we searched PubMed, Embase, and Medline from the establishment of databases up to 2020. We finally included 38 observational studies involving 1 312 609 patients for the assessment of intracranial hemorrhage, and 33 observational studies involving 1 332 956 patients for the assessment of gastrointestinal bleeding. The rates of intracranial hemorrhage were 0.55% in the rivaroxaban group versus 0.91% in the warfarin group (OR 0.59; 95% CI 0.53-0.66; p < .00001, I2 = 78%). The rates of gastrointestinal bleeding were 2.63% in patients with rivaroxaban versus 2.48% in those with warfarin (OR 1.06; 95% CI 0.96-1.17; p < .00001, I2 = 94%). Rivaroxaban could significantly reduce the risk of intracranial hemorrhage in patients with AF than warfarin, but the risk of gastrointestinal bleeding remained controversy due to no statistical significant difference. Notably, a subgroup analysis demonstrated that patients in rivaroxaban group with severe chronic renal diseases or undergoing hemodialysis exposed to less gastrointestinal hemorrhage risk than the group from warfarin.

Lopinavir-Ritonavir in SARS-CoV-2 Infection and Drug-Drug Interactions with Cardioactive Medications

Lopinavir-ritonavir combination is being used for the treatment of SARS-CoV-2 infection. A low dose of ritonavir is added to other protease inhibitors to take advantage of potent inhibition of cytochrome (CYP) P450 3A4, thereby significantly increasing the plasma concentration of coadministered lopinavir. Ritonavir also inhibits CYP2D6 and induces CYP2B6, CYP2C19, CYP2C9, and CYP1A2. This potent, time-dependent interference of major hepatic drug-metabolizing enzymes by ritonavir leads to several clinically important drug-drug interactions. A number of patients presenting with acute coronary syndrome and acute heart failure may have SARS-CoV-2 infection simultaneously. Lopinavir-ritonavir is added to their prescription of multiple cardiac medications leading to potential drug-drug interactions. Many cardiology, pulmonology, and intensivist physicians have never been exposed to clinical scenarios requiring co-prescription of cardiac and antiviral therapies. Therefore, it is essential to enumerate these drug-drug interactions, to avoid any serious drug toxicity, to consider alternate and safer drugs, and to ensure better patient care.

Anticoagulation Control with Acenocoumarol or Warfarin in Non-Valvular Atrial Fibrillation in Primary Care (Fantas-TIC Study)

Introduction: The use of vitamin K antagonists (VKAs) in non-valvular atrial fibrillation (NVAF) is complicated due to the narrow therapeutic margin they present and their unpredictable dose–response relationship. Most studies are based on warfarin, with the results being extrapolated to acenocoumarol. However, studies comparing the two treatments in terms of the degree of anticoagulation control are scarce, justifying the present study. Main factors associated with poor control of time in therapeutic range (TTR) of anticoagulated patients are also studied. Methods: Cross-sectional study, with real-world data from patients treated in primary care (PC). Data were obtained from the System for the Improvement of Research in PC (SIDIAP) database, covering 60,978 NVAF-anticoagulated patients from 287 PC centres in 2018. Descriptive statistics were derived, and odds ratios were estimated by multivariate logistic regression. Results: 41,430 patients were considered: 93% were being treated with acenocoumarol and 7% with warfarin. There was no difference in poor control of TTR between the two types of VKA treatment, acenocoumarol and warfarin (38.9 vs. 38.4; p = 0.610). Poor anticoagulation control was mainly associated with advanced alcoholism (OR = 1.38), liver failure (OR = 1.37) and intracranial haemorrhage (OR = 1.35) as well as female sex, age < 60 years, cardiovascular history, diabetes mellitus and other variables. Conclusions: There is no association between poor anticoagulation control and the type of VKA treatment administered. Factors associated with poor control of TTR must be considered in clinical practice to improve control and decision-making.

Drug-drug interactions between vitamin K antagonists and statins: a systematic review

PURPOSE

Concomitant use of vitamin K antagonists (VKA) and statins is frequent in cardiovascular patients. However, clinical guidelines on this drug combination are divergent. Therefore, we performed a systematic review to evaluate the effect of statin initiation on coagulation among VKA users.

METHODS

Following the PRISMA guidelines, we applied two broad search strategies for the drug interaction between VKA and statins in both Embase and Pubmed; 8623 unique hits were obtained. In the final sample, eight studies were included.

RESULTS

The most frequently used VKA in the studies was warfarin, while simvastatin was the most commonly initiated statin. All included studies showed a minor increase in the anticoagulant effect of VKA following statin initiation during VKA treatment. The reported increases in mean international normalized ratio (INR) ranged from 0.15-0.65.

CONCLUSION

The anticoagulant effect of statin initiation in patients treated with VKA is likely to be of limited clinical relevance but should be evaluated individually.

Performance Characteristics of DOAC Dipstick in Determining Direct Oral Anticoagulants in Urine

Testing for direct oral anticoagulants (DOACs) in patient urine may facilitate medical treatment decisions. The aim of this study was to investigate interobserver variability by 2 independent observers compared to laboratory staff in the visual interpretation of factor Xa (DXI) and thrombin inhibitors (DTI) using the DOAC Dipstick test. We also examined whether test pads reacted to other anticoagulants and abnormal urine colors. The colors of the DOAC Dipstick direct factor Xa inhibitor and thrombin inhibitor pads were interpreted with 100% accuracy (95% confidence interval 0.862 to 1.000) for urine samples from persons treated with apixaban (n = 26), rivaroxaban (n = 24), and dabigatran (n = 29) and without anticoagulant therapy (n = 29). The factor Xa and thrombin inhibitor pads did not interact with heparin, nadroparin, fondaparinux, or coumadin. One µg/mL r-Hirudin and 6 µg/mL argatroban interacted with the DTI pad; however, this is unlikely to cause clinical problems because dabigatran is unlikely to be administered together with r-Hirudin and argatroban in clinical circumstances. Abnormal urine color was reliably detected by the urine color pad, so can prevent false interpretation of the DOAC Dipstick pad colors. In conclusion, we have demonstrated that interobserver variability when interpreting the DOAC Dipstick test strip is low and that factor Xa and thrombin inhibitor pads do not react to other anticoagulants such as heparins and coumadin. R-Hirudin and argatroban can be detected by the thrombin inhibitor pad and abnormal urine colors can be detected by the urine color pad to prevent false interpretation of the results in patient urine samples.

Risk of over-anticoagulation during acute kidney injury in patients treated with vitamin K antagonists

Background

Vitamin K antagonists (VKAs) are still in use for oral anticoagulation, but not all indications allow their replacement by direct oral anticoagulants. Although formal dose reduction is not required in patients with impaired kidney function, case reports indicate that acute kidney injury (AKI) might be associated with derailment of VKA therapy.

Methods

The study retrospectively collected patients from a tertiary nephrology care centre who experienced AKI while being treated with VKA. In these individuals, the international normalized ratio (INR) as a measure of anticoagulant effect during renal failure was compared with a reference time point with stable kidney function.

Results

A total of 100 patients with AKI and ongoing VKA therapy met the inclusion criteria. The majority (76%) of patients had AKI with CKD. Volume depletion (n = 43), septic renal failure (n = 22), decompensated heart failure (n = 18) and toxic renal damage (n = 11) were the most important causes of AKI. The average INR values at the time of AKI were higher than at the reference time point [median 3.17 (range 1.10–13.0) versus 2.24 (1.07–5.17); P < 0.0001]. Fifty-four patients had INR values above the recommended therapeutic range for their indication at the time point of AKI. Bleeding complications occurred in 24 patients during AKI and the VKA dose had to be reduced in 55. Women, patients with low body mass index and patients with diabetes were predisposed to overanticoagulation during AKI.

Conclusions

The effect of AKI on anticoagulation by VKA has not been systematically described. This risk should be considered in patients at high risk for AKI.

Two Strategies for the Dosage of Acenocoumarol Co-Administered with Rifampicin in Staphylococcal Prosthetic Valve Endocarditis

According to current European Society of Cardiology guidelines, for staphylococcal prosthetic valve endocarditis, rifampicin should be one of the drugs used. However, there is a concomitant need for vitamin K antagonists in patients with mechanical prostheses. It is widely known that rifampicin interacts with vitamin K antagonists (VKA), and this interaction makes it difficult to maintain the INR (international normalized ratio) value in the therapeutic range. We present two clinical cases of staphylococcal prosthetic valve endocarditis patients. Two different strategies for dealing with adverse drug interactions have been applied. In the first case, the dose of warfarin was up-titrated until the optimal INR value was obtained. In the second case, due to the history of labile INR values, a decision was made to modify the dosage of warfarin, taking into account pharmacological aspects of drug interactions.

Potential effect of new (E)-4-hydroxy -N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide against acute myocardial infarction: Haemodynamic, biochemical and histological studies

This study aimed to explore the cardioprotective effect of new synthesized coumarin (E)-4-hydroxy-N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide denoted (Hyd.Cou) against myocardial infarction disorders. Male Wistar rats were divided into four groups; Control, isoproterenol (ISO), ISO + Acenocoumarol (Ac) and ISO + Hyd.Cou. Results showed that the ISO group exhibited serious alteration in EGC pattern, significant heart hypertrophy (+33%), haemodynamic disturbance and increase in plasma rate of CK-MB, LDH and troponin-T by 44, 53, and 170%, respectively, as compared to Control. Moreover, isoproterenol induced a rise in plasma angiotensin-converting enzyme activity (ACE) by 49%, dyslipidaemia, and increased thiobarbituric acid-reactive substances (TBARS) by 117% associated with decrease in the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) by 46% and 58%, respectively in myocardium. Interestingly, the molecular docking calculation demonstrated strong interactions of Hyd.Cou with the receptors of the protein disulphide isomerase (PDI) which could highlight the antithrombotic effect. Moreover, Hyd.Cou improved plasma cardiac dysfunction biomarkers, mitigated the ventricle remodelling process and alleviated heart oxidative stress damage. Overall, Hyd.Cou prevented the heart from the remodelling process through inhibition of ACE activity and oxidative stress improvement.

[Adverse drug reactions profiles for abiraterone and enzalutamide: A pharmacovigilance descriptive analysis]

OBJECTIVE

The aim of this study was to describe the profile of adverse drug reactions (ADRs) observed with abiraterone and enzalutamide, based on cases registered in the French regional pharmacovigilance centres to identify potential pharmacovigilance signals.

METHODS

We extracted from the French pharmacovigilance database all cases of ADRs or drug interactions involving abiraterone or enzalutamide from the time they market authorization date until December 31st, 2017. Signal detection results have been transmitted by the French Agency for Health Products (ANSM). The data were compared with those of the risk management plans for each drug and the literature.

RESULTS

Among the 233 observations analyzed, nearly 62% involved abiraterone as a suspect drug and 38% involved enzalutamide; only 1 case involved both drugs. The ADRs profile is different between the drugs. Abiraterone is mostly associated with expected cardiac diseases (heart failure, and QT prolongation), expected with the drug. Also described, several cases of hepatotoxicity have been reported, however some cases with fatal outcome suggest that despite a follow-up of the liver function tests, it is difficult to anticipate this risk. Signals concerning acute renal failure and ischemic stroke have arisen. Enzalutamide is more particularly associated with various neurological disorders (convulsions, hallucinations, fatigue, and memory impairment) expected with the drug. While ischemic heart disease is also expected, signals of heart failure and atrial fibrillation have arisen. A potential hepatotoxicity of the molecule is discussed because of cases of cholestatic hepatitis.

CONCLUSION

The analysis of the French pharmacovigilance database cases allows to confirm an expected and monitored risk profile in the risk management plan for both drugs. Several signals have arisen, some of which will be investigated through a pharmacoepidemiology study.

Thromboembolic and Bleeding Risk in Atrial Fibrillation Patients with Chronic Kidney Disease: Role of Anticoagulation Therapy

Atrial fibrillation (AF) and chronic kidney disease (CKD) are strictly related; several independent risk factors of AF are often frequent in CKD patients. AF prevalence is very common among these patients, ranging between 15% and 20% in advanced stages of CKD. Moreover, the results of several studies showed that AF patients with end stage renal disease (ESRD) have a higher mortality rate than patients with preserved renal function due to an increased incidence of stroke and an unpredicted elevated hemorrhagic risk. Direct oral anticoagulants (DOACs) are currently contraindicated in patients with ESRD and vitamin K antagonists (VKAs), remaining the only drugs allowed, although they show numerous critical issues such as a narrow therapeutic window, increased tissue calcification and an unfavorable risk/benefit ratio with low stroke prevention effect and augmented risk of major bleeding. The purpose of this review is to shed light on the applications of DOAC therapy in CKD patients, especially in ESRD patients.

A Brief Review on Determination of Acenocoumarol in Biological and Pharmaceutical Specimens: Analytical Methodologies

Acenocoumarol is an oral anticoagulant medicinal agent is frequently prescribed for the prophylaxis and the management of thromboembolic events. Acenocoumarol is prescribed in the form of racemic mixture and S- form is a more influential isomer. Acenocoumarol starts quickly with action and absorption, and the effect lasts for 15-20 h. In most patients, the therapeutic prothrombin range is caused 36 h after the primary dose. This review offers a detailed overview of the various analytical methodologies published in the literature from 1976 to uptil now for evaluation acenocoumarol and its combinations in specimens. The present review also stated the chiral analytical methods for the quantification of its enantiomers. A detailed study of the work revealed several analytical methodologies are routinely used for estimation of acenocoumarol includes UV/Vis-Spectrophotometry, liquid chromatography-mass spectrophotometry, high-performance liquid-chromatography, gas chromatography, high-performance thin-layer chromatography, capillary electrophoresis, Fourier-transform infrared spectroscopy and many miscellaneous techniques. Pharmaceutical analysis carried out the prominent task to understand the knowledge of the physicochemical properties of the medicinal agent; since the establishment of a new analytical method is still a challenging task for a research scientist. Thus, the present review will help to research scientist for the development of new analytical methods for the acenocoumarol.

Clopidogrel drug interactions: a review of the evidence and clinical implications

INTRODUCTION

Patients with cardiovascular disease are commonly affected by a number of comorbidities leading to a high prevalence of polypharmacy. Polypharmacy increases the probability of drug-drug interactions (DDIs). Amongst these, DDIs involving clopidogrel, the most commonly utilized platelet P2Y₁₂ inhibitor, is a topic of potential clinical concern.

AREAS COVERED

This article reviews DDIs between clopidogrel and drugs which are widely used in clinical practice. In particular, drugs shown to interfere with the pharmacodynamic and pharmacokinetic effects of clopidogrel and the clinical implications of these findings are reviewed. These drugs include inhibitors of gastric acid secretion, statins, calcium channel blockers, antidiabetic agents, and antimicrobial agents. For the references, we searched PubMed, EMBASE, or the Cochrane Library.

EXPERT OPINION

Clopidogrel-drug interactions are common. Most of these DDIs are limited to laboratory findings showing an impact on clopidogrel-induced antiplatelet effects. While variability in clopidogrel-induced antiplatelet effects is known to affect clinical outcomes, with high platelet reactivity being associated with thrombotic complications among patients undergoing coronary stenting, most studies assessing the clinical implications of clopidogrel-drug interactions have not shown to significantly affect outcomes. However, awareness of these DDIs remains important for optimizing the selection of concomitant therapies.

Simultaneous determination of warfarin and 7-hydroxywarfarin in rat plasma by HPLC-FLD

In this study, high-performance liquid chromatography with fluorescence detection (HPLC-FLD) has been used for the first time, for direct determination of warfarin and its major metabolite, 7-hydroxywarfarin, in rat plasma. The simple and sensitive method was developed using Fortis® reversed-phase diphenyl column (150 × 4.6 mm, 3 μm) and a mobile phase composed of phosphate buffer (25 mmol L-1)/methanol/acetonitrile (70:20:10, V/V/V), adjusted to pH 7.4, at a flow rate of 0.8 mL min-1. The diphenyl chemistry of the stationary phase provided a unique selectivity for separating the structurally related aromatic analytes, warfarin and 7-hydroxywarfarin, allowing their successful quantification in the complex plasma matrix. The method was linear over the range 0.01-25 μg mL-1, for warfarin and 7-hydroxywarfarin, and was found to be accurate, precise and selective in accordance with US FDA guidance for bioanalytical method validation. The method was sensitive enough to quantify 0.01 μg mL-1 of warfarin and 7-hydroxywarfarin (LLOQ) using only 100 μL of plasma. The applicability of this method was demonstrated by analyzing samples obtained from rats after oral administration of a single warfarin dose, and studying warfarin and 7-hydroxywarfarin pharmacokinetics.

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.

Piperine Alters the Pharmacokinetics and Anticoagulation of Warfarin in Rats

Introduction

Piperine, the bioactive compound of black pepper, and warfarin are metabolized by cytochrome P450 enzymes and are both highly plasma protein-bound compounds. In this study, we evaluated the effect of co-administered piperine on the pharmacokinetics and anticoagulation of warfarin in rats.

Methods

We studied four Sprague-Dawley rat groups: a negative control group receiving only oral warfarin, a test group receiving warfarin plus piperine, a positive control group receiving warfarin plus sulfaphenazole (CYP2C inhibitor), and another positive control group receiving warfarin plus ketoconazole (CYP3A inhibitor). We also analyzed plasma concentrations of warfarin and its major metabolite, 7-hydoxywarfarin. Blood clotting time, calculated as international normalized ratio (INR), was also measured.

Results

Our results showed that although co-administration of piperine produced a non-significant decrease in warfarin concentrations, it resulted in significantly lower 7-hydroxywarfarin metabolite concentrations. Piperine significantly decreased, by sixfold, AUC_0–∞, by eightfold, C_max, but significantly increased, by fivefold, CL/F and, by sixfold, Vd/F of 7-hydroxywarfarin. The INR values were consistent with the decrease in warfarin concentration in the presence of piperine and showed a significant decrease at 24 h after warfarin dose.

Conclusion

We conclude that piperine could be a potent inhibitor of cytochrome P450 metabolism of warfarin in vivo and, contrary to the expectation, may reduce the plasma concentration and anticoagulation of warfarin. This interaction could have a clinical significance and should be investigated in patients.

Coumarin as a structural component of substrates and probes for serine and cysteine proteases

Coumarins represent well-established structures to introduce fluorescence into tool compounds for biochemical investigations. They are valued for their small size, chemical stability and accessibility as well as their tunable photochemical properties. As components of fluorophore/quencher pairs or FRET donor/acceptor pairs, coumarins have frequently been applied in substrate mapping approaches for serine and cysteine proteases. This review also focuses on the incorporation of coumarins into the side chain of amino acids and the exploitation of the resulting fluorescent amino acids for the positional profiling of protease substrates. The protease-inhibiting properties of certain coumarin derivatives and the utilization of coumarin moieties to assemble activity-based probes for serine and cysteine proteases are discussed as well.

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Coumarins represent well-established structures to introduce fluorescence into tool compounds for biochemical investigations.

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They are valued for their small size, chemical stability and accessibility as well as their tunable photochemical properties.

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Coumarins are components of fluorophore/quencher pairs or FRET donor/acceptor pairs in substrate mapping of proteases.

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Coumarins have been incorporated into amino acids side chains to be used for the positional profiling of protease substrates.

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Coumarins have protease-inhibiting properties and are used for activity-based probes for serine and cysteine proteases.