Pharmacology of antithrombotic drugs: an assessment of oral antiplatelet and anticoagulant treatments

Dual Antiplatelet Therapy with Clopidogrel and Aspirin Versus Aspirin Monotherapy in Patients Undergoing Coronary Artery Bypass Graft Surgery

Background The optimal antiplatelet therapy after coronary artery bypass grafting remains unclear. We evaluated the association of dual antiplatelet therapy (DAPT) with clopidogrel plus aspirin and clinical outcomes among patients undergoing coronary artery bypass grafting. Methods and Results A total of 18 069 consecutive patients who underwent primary isolated coronary artery bypass grafting between 2013 and 2017 were identified from a contemporary registry, and 10 854 (60.1%) received DAPT with clopidogrel plus aspirin as determined by claimed prescriptions after surgery. Cox regression models with inverse probability of treatment weighting were used to examine the associations between DAPT and outcomes. Patients who received DAPT, compared with those who received aspirin monotherapy, had a lower incidence of a composite of all-cause death, myocardial infarction, stroke, or repeat revascularization at 6 months (2.9% versus 4.2%; inverse probability of treatment weighting-adjusted hazard ratio [HR], 0.65; 95% CI, 0.55-0.77; P<0.001) as well as death (HR, 0.61; 95% CI, 0.41-0.90), myocardial infarction (HR, 0.55; 95% CI, 0.40-0.74), and stroke (HR, 0.58; 95% CI, 0.46-0.74). The incidence of major bleeding did not differ significantly between the 2 groups (HR, 1.11; 95% CI, 0.69-1.78). Similar results were noted across multiple subgroups as well as when using different analytic methods. Conclusions Among patients undergoing coronary artery bypass grafting, DAPT with clopidogrel plus aspirin as secondary prevention was associated with reduced risk of major adverse cardiovascular and cerebrovascular events within 6 months as compared with aspirin monotherapy, and there was no significant increase in major bleeding.

Inappropriate Use of Oral Antithrombotic Combinations in an Outpatient Setting and Associated Risks: A French Nationwide Cohort Study

With the increase in prevalence of cardiovascular diseases, multimorbidity, and medical progress, oral antithrombotic (AT) combinations are increasingly prescribed. The aims of this study were to estimate the incidence of oral AT combinations, their appropriateness (defined as indications compliant with guidelines), and the related risk of major bleeding (i.e., leading to hospitalization) or death, among new users. We conducted a 5-year historical cohort study, using the French national healthcare database, including all individuals ≥ 45 years old with a first delivery of oral ATs between 1 January 2013 and 31 December 2017. The cumulative incidence of oral AT combinations was estimated with the Fine and Gray method, taking into account the competitive risk of death. We compared the cumulative incidence of major bleeding according to the type of oral AT treatment initiated at study entry (monotherapy or oral AT combinations). During the study period, 22,220 individuals were included (mean (SD) age 68 (12) years). The cumulative incidence of oral AT combinations at 5 years was 27.8% (95% confidence interval (CI) 26.8–28.9). Overall, 64% of any oral AT combinations did not comply with guidelines. The cumulative incidence of major bleeding and death in the whole cohort at 5 years was 4.1% (95% CI 3.7–4.6) and 10.8% (95% CI 10.1–11.6), respectively. Risk of major bleeding increased among individuals with oral AT combinations versus oral AT monotherapy at study entry (subdistribution hazard ratio sHR: 2.16 (1.01–4.63)); with no difference in terms of death. The use of oral AT combinations among oral AT users is frequent, often inappropriately prescribed, and associated with an increased risk of major bleeding.

Trends in ST-elevation myocardial infarction

AIMS

Despite recent progress in coronary artery disease treatment, ST-segment elevation myocardial infarction (STEMI) remains a very high-risk medical condition. Whether recent patients' outcomes, following implementation of the 2012 European Society of Cardiology (ESC) STEMI guidelines have improved, is yet unclear.

METHODS AND RESULTS

The study was based on a prospective detailed registry of 2004 consecutive patients with STEMI treated with primary percutaneous coronary intervention (pPCI). We compared trends during two different time periods (2006-2012 vs. 2012-2018). Endpoints included mortality and major adverse cardiac events (MACE: death, repeat myocardial infarction, target vessel revascularization and coronary artery bypass surgery) at 1 month, 1 and 2 years. Rates of transradial interventions have risen significantly (67.3 vs. 42.0%; P < 0.01), as have rates of prasugrel administration (69.8 vs. 4.5%; P < 0.01) and use of drug eluting stents (75.5 vs. 56.5%; P < 0.01). Both at 1 and at 2 years, MACE was significantly lower in the later period (11.6 vs. 20.9%; P < 0.01 and 18.9 vs. 25.4%; P < 0.01 respectively), whereas mortality was only significantly lower after 1 year (5.8 vs. 8.6%; P = 0.02). Cox regression identified the later period (2012-2018) to independently and favorably impact MACE (hazard ratio, -0.69; 95% CI, 0.56-0.85; P < 0.01) but not mortality (hazard ratio, -0.76; 95% CI, 0.54-1.05; P = 0.09).

CONCLUSION

Among patients treated with pPCI for STEMI, adoption of the contemporary evidence-based treatments is associated with better MACE derived outcomes, following the inception of the 2012 ESC guidelines. Nonetheless, the long-term mortality was marginally (but not significantly) lower, which indicates an unmet need for further improvement.

Antithrombotic regimens in females with symptomatic lower extremity peripheral arterial disease: protocol for a systematic review and meta-analysis

INTRODUCTION

Patients with peripheral arterial disease (PAD) are at increased risk for systemic arterial thromboembolic events. Females represent a unique subset of patients with PAD, who differ from males in important ways: they have smaller diameter vessels, undergo lower extremity bypass less frequently and experience higher rates of graft occlusion, amputation and mortality than males. Females also trend towards higher rates of major coronary events and cardiovascular mortality. Current guidelines recommend monoantiplatelet therapy (MAPT) for secondary prevention in patients with symptomatic PAD. However, indications for more intensive antithrombotic therapy in this cohort-especially among females who are frequently under-represented in randomised controlled trials (RCTs)-remain unclear. As newer antithrombotic therapies emerge, some RCTs have demonstrated differential effects in females versus males. A systematic review is needed to quantify the rates of arterial thromboembolic and bleeding events with different antithrombotic regimens in females with symptomatic PAD.

METHODS AND ANALYSIS

We will search MEDLINE, Embase and the Cochrane Central Register of Controlled trials for published RCTs that include females with symptomatic PAD and compare full dose anticoagulation±antiplatelet therapy, dual pathway inhibition or dual antiplatelet therapy with MAPT. Title, abstract and full-text screening will be conducted in duplicate by three reviewers. Authors will be contacted to obtain sex-stratified outcomes as needed. Risk of bias will be assessed using the Cochrane Risk of Bias tool. Data will be extracted by independent reviewers and confirmed by a second reviewer. Quantitative synthesis will be conducted using Review Manager (RevMan) V.5 for applicable outcomes data. Planned subgroup analysis by PAD severity, vascular intervention and indication for antithrombotics will be conducted where data permits.

ETHICS AND DISSEMINATION

Ethics approval is waived as the study does not involve primary data collection. This review will be submitted for publication in a peer-reviewed journal and for presentation at national and international scientific meetings.

TRIAL REGISTRATION NUMBER

This protocol was registered with the PROSPERO International Prospective Register of Systematic Reviews (ID# CRD42020196933).

The pleiotropic effects of antithrombotic drugs in the metabolic-cardiovascular-neurodegenerative disease continuum: impact beyond reduced clotting

Antithrombotic drugs are widely used for primary and secondary prevention, as well as treatment of many cardiovascular disorders. Over the past few decades, major advances in the pharmacology of these agents have been made with the introduction of new drug classes as novel therapeutic options. Accumulating evidence indicates that the beneficial outcomes of some of these antithrombotic agents are not solely related to their ability to reduce thrombosis. Here, we review the evidence supporting established and potential pleiotropic effects of four novel classes of antithrombotic drugs, adenosine diphosphate (ADP) P2Y12-receptor antagonists, Glycoprotein IIb/IIIa receptor Inhibitors, and Direct Oral Anticoagulants (DOACs), which include Direct Factor Xa (FXa) and Direct Thrombin Inhibitors. Specifically, we discuss the molecular evidence supporting such pleiotropic effects in the context of cardiovascular disease (CVD) including endothelial dysfunction (ED), atherosclerosis, cardiac injury, stroke, and arrhythmia. Importantly, we highlight the role of DOACs in mitigating metabolic dysfunction-associated cardiovascular derangements. We also postulate that DOACs modulate perivascular adipose tissue inflammation and thus, may reverse cardiovascular dysfunction early in the course of the metabolic syndrome. In this regard, we argue that some antithrombotic agents can reverse the neurovascular damage in Alzheimer's and Parkinson's brain and following traumatic brain injury (TBI). Overall, we attempt to provide an up-to-date comprehensive review of the less-recognized, beneficial molecular aspects of antithrombotic therapy beyond reduced thrombus formation. We also make a solid argument for the need of further mechanistic analysis of the pleiotropic effects of antithrombotic drugs in the future.

Investigating Intestinal Transporter Involvement in Rivaroxaban Disposition through Examination of Changes in Absorption

PURPOSE

The involvement of the intestinally expressed xenobiotic transporters P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP) have been implicated in rivaroxaban disposition based on in vitro studies, similar to what had previously been proposed for apixaban. We recently showed that these efflux transporters were not clinically relevant for apixaban disposition and examine here their relevance for this second Factor Xa inhibitor.

METHODS

Using recently published methodologies to discern metabolic- from transporter- mediated drug interactions, a critical evaluation was undertaken of 9 rivaroxaban studies reporting 12 DDIs, one study of food effects and one study of hepatic function.

RESULTS

Rationale examination of these clinical studies using basic pharmacokinetic theory finds little support for the clinical significance of intestinal efflux transporters in rivaroxaban disposition. Drug-drug interactions are most likely adequately predicted based on the level of CYP 3A metabolism.

CONCLUSION

These analyses indicate that inhibition of efflux transporters appears to have negligible, clinically insignificant effects on the rivaroxaban absorption process, which is consistent with the concern that predictions based on in vitro measures may not translate to a clinically relevant interaction in vivo. We emphasize the need to evaluate gastric emptying, dissolution and other processes related to absorption when using MAT changes to indicate efflux transporter inhibition.

Antiplatelet Drug Use and Breast Cancer Risk in a Prospective Cohort of Postmenopausal Women

BACKGROUND

Epidemiologic evidence is insufficient to draw conclusions on the impact of low-dose aspirin use on breast cancer risk, and the potential impact of other antiplatelet drugs such as clopidogrel needs to be explored.

METHODS

We investigated the association between breast cancer risk and low-dose aspirin or clopidogrel use in the E3N cohort, which includes 98,995 women, with information on breast cancer risk factors collected from biennial questionnaires matched with drug reimbursement data available from 2004. Women with at least two reimbursements of the drug of interest in any previous 3-month period were considered "ever" exposed. Exposure was considered as time-varying and multivariable Cox regression models were used to estimate HRs of breast cancer.

RESULTS

Among 62,512 postmenopausal women followed during 9 years on average, 2,864 breast cancer cases were identified. Compared with never use, a transient higher breast cancer risk was observed during the third year of low-dose aspirin use [HR2-≤3 years of use = 1.49 (1.08-2.07)], followed by a lower risk [HR4+ years of use = 0.72 (0.52-0.99)]. Clopidogrel ever use was associated with a higher breast cancer risk [HR, 1.30 (1.02-1.68)], restricted to estrogen receptor negative (ER-) tumors [HRER+ = 1.14 (0.83-1.57), HRER- = 3.07 (1.64-5.76), P homogeneity = 0.01].

CONCLUSIONS

Low-dose aspirin was associated with a lower breast cancer risk only after several years of use, while ever use of clopidogrel was associated with a higher ER- breast cancer risk.

IMPACT

Antiplatelet drugs are not good pharmacologic candidates for breast cancer prevention.

AXL, an Important Host Factor for DENV and ZIKV Replication

Flaviviruses, as critically important pathogens, are still major public health problems all over the world. For instance, the evolution of ZIKV led to large-scale outbreaks in the Yap island in 2007. DENV was considered by the World Health Organization (WHO) as one of the 10 threats to global health in 2019. Enveloped viruses hijack a variety of host factors to complete its replication cycle. Phosphatidylserine (PS) receptor, AXL, is considered to be a candidate receptor for flavivirus invasion. In this review, we discuss the molecular structure of ZIKV and DENV, and how they interact with AXL to successfully invade host cells. A more comprehensive understanding of the molecular mechanisms of flavivirus-AXL interaction will provide crucial insights into the virus infection process and the development of anti-flavivirus therapeutics.

Clinical significance of high on-treatment platelet reactivity in patients with prolonged clopidogrel therapy

BACKGROUND/AIMS

Prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel beyond 1 year has been shown to reduce ischemic events at the expense of increased bleeding. However, limited data are available on the clinical significance of platelet reactivity (PR) at 1 year.

METHODS

We retrospectively identified 331 patients who underwent percutaneous coronary intervention (PCI) and assessed the on-clopidogrel PR using VerifyNow P2Y12 assay at 1 year in a single center. Two hundred eleven patients were on DAPT for > 1 year. The relationship between high on-treatment platelet reactivity (HPR) at 1 year and clinical outcomes beyond 1 year, as well as the longitudinal change in PR was analyzed.

RESULTS

At 1 year, 135 (64%) patients showed HPR and 76 (36%) did not. There was a significant increase in ischemic endpoint events, including cardiovascular death, non-fatal myocardial infarction, and stroke/transient ischemic attack in patients with compared to without HPR at 1 year (hazard ratio [HR], 2.68; 95% confidence interval [CI], 1.06 to 6.77; p = 0.036). However, the incidence of any Bleeding Academic Research Consortium bleeding was significantly lower in the HPR group (HR, 0.11; 95% CI, 0.02 to 0.65; p = 0.015). In the longitudinal analysis, PR significantly decreased from post-load to 1 year after index PCI in the non-HPR group. Conversely, the HPR group showed high PR from baseline through 1 year.

CONCLUSION

HPR at 1 year may be a useful surrogate for predicting ischemic and bleeding events in patients on prolonged DAPT. Patients with and without HPR at 1 year showed different patterns of longitudinal change in PR.

Perioperative Management of Chronic Antithrombotic Agents in Elective Hip and Knee Arthroplasty

Total hip and knee arthroplasty are common major orthopedic operations being performed on an increasing number of patients. Many patients undergoing total joint arthroplasty (TJA) are on chronic antithrombotic agents due to other medical conditions, such as atrial fibrillation or acute coronary syndrome. Given the risk of bleeding associated with TJAs, as well as the risk of thromboembolic events in the post-operative period, the management of chronic antithrombotic agents perioperatively is critical to achieving successful outcomes in arthroplasty. In this review, we provide a concise overview of society guidelines regarding the perioperative management of chronic antithrombotic agents in the setting of elective TJAs and summarize the recent literature that may inform future guidelines. Ultimately, antithrombotic regimen management should be patient-specific, in consultation with cardiology, internal medicine, hematology, and other physicians who play an essential role in perioperative care.

Impact of SMTP Targeting Plasminogen and Soluble Epoxide Hydrolase on Thrombolysis, Inflammation, and Ischemic Stroke

Stachybotrys microspora triprenyl phenol (SMTP) is a large family of small molecules derived from the fungus S. microspora. SMTP acts as a zymogen modulator (specifically, plasminogen modulator) that alters plasminogen conformation to enhance its binding to fibrin and subsequent fibrinolysis. Certain SMTP congeners exert anti-inflammatory effects by targeting soluble epoxide hydrolase. SMTP congeners with both plasminogen modulation activity and anti-inflammatory activity ameliorate various aspects of ischemic stroke in rodents and primates. A remarkable feature of SMTP efficacy is the suppression of hemorrhagic transformation, which is exacerbated by conventional thrombolytic treatments. No drug with such properties has been developed yet, and SMTP would be the first to promote thrombolysis but suppress disease-associated bleeding. On the basis of these findings, one SMTP congener is under clinical study and development. This review summarizes the discovery, mechanism of action, pharmacological activities, and development of SMTP.

Multifactorial Background for a Low Biological Response to Antiplatelet Agents Used in Stroke Prevention

Effective platelet inhibition is the main goal of the antiplatelet therapy recommended as a standard treatment in the secondary prevention of non-embolic ischemic stroke. Acetylsalicylic acid (aspirin) and clopidogrel are commonly used for this purpose worldwide. A low biological response to antiplatelet agents is a phenomenon that significantly reduces the therapeutic and protective properties of the therapy. The mechanisms leading to high on-treatment platelet reactivity are still unclear and remain multifactorial. The aim of the current review is to establish the background of resistance to antiplatelet agents commonly used in the secondary prevention of ischemic stroke and to explain the possible mechanisms. The most important factors influencing the incidence of a low biological response were demonstrated. The similarities and the differences in resistance to both drugs are emphasized, which may facilitate the selection of the appropriate antiplatelet agent in relation to specific clinical conditions and comorbidities. Despite the lack of indications for the routine assessment of platelet reactivity in stroke subjects, this should be performed in selected patients from the high-risk group. Increasing the detectability of low antiaggregant responders, in light of its negative impact on the prognosis and clinical outcomes, can contribute to a more individualized approach and modification of the antiplatelet therapy to maximize the therapeutic effect in the secondary prevention of stroke.

Effectiveness and safety among direct oral anticoagulants in nonvalvular atrial fibrillation: A multi-database cohort study with meta-analysis

AIMS

There are conflicting signals in the literature about comparative safety and effectiveness of direct oral anticoagulants (DOACs) for nonvalvular atrial fibrillation (NVAF).

METHODS

We conducted multicentre matched cohort studies with secondary meta-analysis to assess safety and effectiveness of dabigatran, rivaroxaban and apixaban across 9 administrative healthcare databases. We included adults with NVAF initiating anticoagulation therapy (dabigatran, rivaroxaban or apixaban), and constructed 3 cohorts to compare DOACs pairwise. The primary outcome was pooled hazard ratio (pHR) of ischaemic stroke or systemic thromboembolism. Secondary outcomes included pHR of major bleeding, and a composite of stroke, major bleeding, or all-cause mortality. We used proportional hazard Cox regressions models, and pooled estimates were obtained with random effect meta-analyses.

RESULTS

The cohorts included 73 414 new users of dabigatran, 92 881 of rivaroxaban, and 61 284 of apixaban. After matching, the pHRs (95% confidence intervals) comparing rivaroxaban initiation to dabigatran were: 1.11 (0.93, 1.32) for ischaemic stroke or systemic thromboembolism, 1.26 (1.09, 1.46) for major bleeding, and 1.17 (1.05, 1.30) for the composite endpoint. For apixaban vs dabigatran, they were: 0.91 (0.74, 1.12) for ischaemic stroke or systemic thromboembolism, 0.89 (0.75, 1.05) for major bleeding, and 0.94 (0.78 to 1.14) for the composite endpoint. For apixaban vs rivaroxaban, they were: 0.85 (0.74, 0.99) for ischaemic stroke or systemic thromboembolism, 0.61 (0.53, 0.70) for major bleeding, and 0.82 (0.76, 0.88) for the composite endpoint.

CONCLUSION

We found that apixaban use is associated with lower risks of stroke and bleeding compared with rivaroxaban, and similar risks compared with dabigatran.

The impact of ABCB1 and CES1 polymorphisms on dabigatran pharmacokinetics and pharmacodynamics in patients with atrial fibrillation

AIMS

Our study aimed to determine the impact of genetic polymorphisms of ABCB1 and CES1 on the pharmacokinetics (PK) and pharmacodynamics (PD) of dabigatran in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

We conducted a prospective study and enrolled NVAF patients treated with dabigatran. Blood samples were obtained from each patient and used for genotyping and determination of plasma dabigatran concentration (PDC) and coagulation parameters including activated partial thromboplastin time (APTT) and thrombin time. Patients' demographics and clinical outcomes from scheduled follow-up visits were all recorded. Statistical analysis was performed to identify the impact of genetic polymorphisms on the PK/PD and bleeding risk of dabigatran.

RESULTS

A total of 198 patients were included in analysis. For the ABCB1 polymorphisms rs4148738 and rs1045642, no significant association was found with dabigatran PK/PD. For the CES1 polymorphism rs8192935, the minor allele(C) was associated with increased trough PDCs (ANOVA: P < .001; CC vs. TT genotype, P < .001; CT vs. TT genotype, P = .014) and with APTT values at trough level (P = .015). For the CES1 polymorphism rs2244613, the minor allele(A) carriers had higher levels of trough PDC than noncarriers (ANOVA: P < .001; AA vs. CC genotype, P < .001; CA vs. CC genotype, P = .004) and increased risk for minor bleeding (P = .034; odds ratio = 2.71, 95% confidence interval 1.05-7.00).

CONCLUSION

Our study indicated that the minor allele(C) on the CES1 SNP rs8192935 was associated with PDCs and APTT values at trough level. The minor allele(A) on the CES1 SNP rs2244613 was associated with increased trough PDCs and higher risk for minor bleeding in NVAF patients treated with dabigatran.

Using the Case-Crossover Design to Assess Short-Term Risks of Bleeding and Arterial Thromboembolism After Switching Between Oral Anticoagulants in a Population-Based Cohort of Patients With Atrial Fibrillation

Using nationwide Danish registries, we conducted a population-based case-crossover study evaluating the association between switching from a vitamin K antagonist (VKA) to a direct oral anticoagulant (DOAC), and vice versa, and 30-day risks of bleeding and arterial thromboembolism in patients with atrial fibrillation (AF). The case-crossover population was identified among oral anticoagulant users during 2011-2018 (n = 123,217) as patients with AF with 1) a case-defining outcome and 2) an anticoagulant switch during the 180 days preceding the outcome. Odds ratios were estimated using conditional logistic regression by comparing the occurrence of switching during the 30-day window immediately preceding the outcome to that in reference windows in the same individual 60-180 days before the outcome. The case-crossover populations for switching from VKA to DOAC and DOAC to VKA comprised 1,382 and 287 case patients, respectively. Switching from VKA to DOAC, but not from DOAC to VKA, was associated with an increased short-term risk of bleeding (odds ratio = 1.42; 95% confidence intervals: 1.13, 1.79, and 1.06; and 0.64, 1.75, respectively) and ischemic stroke (odds ratio = 1.74; 95% confidence intervals: 1.21, 2.51, and 0.92; and 0.46, 1.83, respectively). Our findings suggest that switching from VKA to DOAC is an intermittent risk factor of bleeding and ischemic stroke in patients with AF.

Synthetic high-density lipoproteins loaded with an antiplatelet drug for efficient inhibition of thrombosis in mice

Antiplatelet agents offer a desirable approach to thrombosis prevention through the reduction of platelet reactivity. However, major bleeding events greatly attenuate the clinical outcomes of most antithrombotic agents. Therefore, the development of safer and more effective strategies to prevent vascular occlusion and avoid bleeding is urgently needed. A reconstituted nanoparticle, synthetic high-density lipoprotein (sHDL), which mimics the native HDL, has been established as clinically safe and is easily manufactured on a large scale. In this study, we propose that the delivery of the antiplatelet drug ML355, a selective inhibitor of 12(S)-lipoxygenase (12-LOX), by sHDL will efficiently inhibit thrombosis by targeting ML355 to the intended site of action, improving the pharmaceutical profile and harnessing the innate antithrombotic efficacy of the sHDL carrier. Our data show that ML355-sHDL exhibits more potent inhibition of thrombus formation in both small arterioles and larger arteries in mice without impairing the normal hemostasis in vivo.

ADP/P2Y1 aggravates inflammatory bowel disease through ERK5-mediated NLRP3 inflammasome activation

Inflammasomes are essential for inflammation and pathogen elimination in response to microbial infection and endogenous danger signals. However, the mechanism of inflammasome activation by endogenous danger signals mediated posttranslational modification and the connection between inflammasomes and inflammatory diseases remains elusive. In this study, we found that ADP was highly released from injured colonic tissue as a danger signal during inflammatory bowel disease. Consequently, extracellular ADP activated the NLRP3 inflammasome through P2Y₁ receptor-mediated calcium signaling, which led to the maturation and secretion of IL-1β and further aggravation of experimental colitis. Genetic ablation or pharmacological blockade of the P2Y₁ receptor significantly ameliorated DSS-induced colitis and endotoxic shock through reducing NLRP3 inflammasome activation. Moreover, ERK5-mediated tyrosine phosphorylation of ASC was essential for activation of the NLRP3 inflammasome. Thus, our study provides a novel theoretical basis for posttranslational modification of ASC in NLRP3 inflammasome activation and revealed that ADP/P2Y₁ is a potential drug target for inflammatory bowel disease.

Cost-effectiveness of CYP2C19 LOF-guided antiplatelet therapy in Chinese patients with acute coronary syndrome

Aim: This study aimed to evaluate the cost-effectiveness of CYP2C19 loss-of-function(LOF) allele-guided antiplatelet therapy compared with the universal use of clopidogrel or ticagrelor among Chinese patients with acute coronary syndrome undergoing percutaneous coronary intervention. Methods: A two-part cost-effectiveness model comprising of a 1-year decision tree and a long-term Markov model was utilized to simulate outcomes of three treatment strategies: universal use of clopidogrel (75 mg daily) or universal use of ticagrelor 90 mg twice daily for all patients and CYP2C19 LOF-guided therapy (LOF allele carriers receiving ticagrelor, LOF allele noncarriers receiving clopidogrel). Model outcomes included quality-adjusted life years (QALYs) gained, direct medical costs and incremental cost-effectiveness ratios (ICERs). ICERs less than one-time gross domestic product per capita in China 59,660 yuan/QALY were considered cost-effective. Results: Base-case analysis showed 'universal ticagrelor use' was cost-effective for an ICER of 33,875 yuan per QALY gained compared with 'universal clopidogrel use' of which gained a 1.6932 QALYs at lowest life-long cost of 2450 yuan. CYP2C19 LOF-guided therapy had an effectiveness of 1.6975 QALYs at a cost of 2812 yuan, for an ICER of 84,118 yuan per QALY gained relative to 'universal clopidogrel use'. Sensitivity analysis demonstrated that base-case results were significantly affected by five factors: the risk ratio of 'non-fatal myocardial infarction', 'non-fatal stroke' and 'cardiovascular death' in ticagrelor versus clopidogrel and the annual costs of clopidogrel and ticagrelor. According to the results of Monte Carlo simulation, when willing to pay is about 32,000 yuan, patients willing to receive clopidogrel or ticagrelor are approximately equal. Conclusion: Optimal antiplatelet treatment is affected by lots of factors. The results of our study demonstrated that 'universal ticagrelor use' was cost-effective compared with 'universal clopidogrel use' for Chinese acute coronary syndrome patients with percutaneous coronary intervention.

The Phenomenon of Clopidogrel High On-Treatment Platelet Reactivity in Ischemic Stroke Subjects: A Comprehensive Review

Clopidogrel is increasingly being used for the secondary prevention of ischemic stroke according to the updated guidelines on acute stroke management. Failure to achieve a drug response is referred to as clopidogrel resistance. Similarly, a higher activation of platelets during clopidogrel therapy—high on-treatment platelet reactivity—is equivalent to a reduced effectiveness of a therapy. Clopidogrel resistance is considered to be a common and multifactorial phenomenon that significantly limits the efficacy of antiplatelet agents. The aim of the current study is to review the latest literature data to identify the prevalance and predictors of clopidogrel high on-treatment platelet reactivity among stroke subjects and to establish the potential impact on clinical outcomes and prognosis. Clinical databases were searched by two independent researchers to select relevant papers on the topic, including all types of articles. Several important predictors contributing to clopidogrel resistance were identified, including genetic polymorphisms, the concomitant use of other drugs, or vascular risk factors, in particular nonsmoking and diabetes. Clopidogrel high on-treatment platelet reactivity has a negative impact on the clinical course of stroke, worsens the early- and long-term prognoses, and increases the risk of recurrent vascular events. Platelet function testing should be considered in selected stroke individuals, especially those predisposed to clopidogrel resistance, for whom an improvement in the efficacy of antiplatelet therapy is essential. This particular group may become the greatest beneficiaries of the modification of existing therapy based on platelet function monitoring.

Iatrogenesis and neurological manifestations in the elderly

Older people are often exposed to polypharmacy in a multimorbidity context. Inappropriate polypharmacy is often harmful, increasing the risk of inappropriate prescriptions and therefore adverse drug events (ADEs). Five to 20% of all hospital admissions are related to ADE in older people, among which 40 to 70% could be prevented. However, identifying ADEs and drug-related admissions in the elderly is challenging because ADEs often present as common geriatric problems such as falls, delirium, which might be due to the aging process, underlying diseases, and/or medications. In the pharmacovigilance database of the World Health Organization, drug-related neurological manifestations are the third reported cause of ADEs in the elderly, and neurological drugs are the third leading class of medications involved in ADEs. We must therefore be particularly vigilant, both in our prescriptions but also in our diagnoses to avoid prescribing inappropriate treatments and detect ADEs. Even though multiple pharmacologic changes occur in the elderly (absorption, distribution, drug metabolism and excretion), most of medications are still often prescribed at the same daily dosage as in young adults. When prescribing any drug for old patients, we should remember that daily intake should be adapted to these specificities, keeping in mind the old well-known aphorism "start low, go slow". In this review, we describe the main drug-related neurological manifestations (drug-induced movement disorders, falls, seizures, delirium, hypoglycemia, stroke, hyponatremia, peripheral neuropathy and myopathy, and serotonin syndrome) and the main drugs associated with neurological manifestations (dopamine receptor blocking agents, antithrombotics, anticholinergics, beta-lactams, antidepressants, benzodiazepines, mood stabilizers).

Diallyl Trisulfide Inhibits Platelet Aggregation through the Modification of Sulfhydryl Groups

Diallyl trisulfide (DATS) is a secondary metabolite of allicin, a volatile organosulfur flavoring compound generated by the crushing of garlic. These compounds have various medicinal effects such as antiplatelet activity. In this study, we demonstrated for the first time the cellular mechanism involved in the inhibition of platelet aggregation by DATS and dipropyl trisulfide (DPTS), which is a saturated analogue of DATS. Washed murine platelets were incubated with these sulfides, and platelet aggregation was evaluated by light transmission aggregometry. The amount of reaction products produced by DATS, DPTS, and glutathione (GSH) was measured using liquid chromatography-mass spectrometry. Compared with DPTS, DATS potently inhibited platelet aggregation induced by thrombin, U46619, and collagen. N-Ethylmaleimide (NEM), which is commonly used to modify sulfhydryl groups, also suppressed platelet aggregation. The reactivity of DATS with GSH was higher than that of DPTS. These data suggested that DATS inhibited platelet aggregation through the reaction of sulfhydryl groups.

When is the optimal time to discontinue clopidogrel before in-hospital coronary bypass surgery? A closer look at the current literature

BACKGROUND

Clopidogrel and other P2Y12 inhibitors have become the standard of care among patients presenting with acute coronary syndromes. A substantial proportion of these patients require surgical revascularization during index hospitalization.

HYPOTHESIS

Guidelines recommend a 5-day waiting period off clopidogrel before coronary artery bypass grafting (CABG) to reduce hemorrhagic complications. These recommendations are not routinely followed in clinical practice, while recent studies also propose shorter waiting periods off clopidogrel for patients awaiting in-hospital CABG.

METHODS

A preliminary PubMed search was conducted using the following MeSH terms under the publication type "Hemorrhage:" "Clopidogrel," AND "Coronary Artery Bypass." Relevant studies and guidelines were then reviewed and selected based on a predetermined criteria. Studies that formulated the current recommendations for stopping clopidogrel preoperative to CABG are discussed in detail this review.

RESULTS

A comprehensive review of recent evidence illustrates mixed bleeding and transfusion outcomes among CABG patients with preoperative exposure to clopidogrel in less than 5 days.

CONCLUSIONS

The optimal discontinuation time of clopidogrel before CABG is still poorly defined. The recommendation of a 5-day washout period for clopidogrel should be reconsidered to be on par with current clinical practice.

Stratified Approaches to Antiplatelet Therapies Based on Platelet Reactivity Testing

Antiplatelet therapy with P2Y₁₂ receptor inhibitors (clopidogrel, prasugrel, ticagrelor, cangrelor) is a cornerstone of medical therapy after percutaneous coronary interventions. Significant prevalence of high on-treatment platelet reactivity (HTPR) on clopidogrel treatment led to introduction of more potent P2Y₁₂ inhibitors: prasugrel (a third generation thienopyridine), ticagrelor, and cangrelor (cyclopentyl-triazolo-pyrimidines). Nevertheless, more potent platelet inhibition and resulting low on-treatment platelet reactivity (LTPR) has led to increased risk of major bleeding events. These limitations resulted in a need for an individualized antiplatelet therapy approach. This review discusses the current role and future perspectives of diagnostic tools such as platelet function testing to optimize antiplatelet therapy with a focus on deescalating therapies to reduce bleeding risks.

Ischemic Stroke and Systemic Embolism in Warfarin Users With Atrial Fibrillation or Heart Valve Replacement Exposed to Dicloxacillin or Flucloxacillin

The antibiotics dicloxacillin and flucloxacillin induce cytochrome P450-dependent metabolism of warfarin. We explored the influence of these drug-drug interactions on the clinical effectiveness of warfarin therapy due to atrial fibrillation or heart valve replacement. Using the population-based Danish registers, we performed a propensity-score matched cohort study including around 50,000 episodes of dicloxacillin/flucloxacillin matched to phenoxymethylpenicillin and to no antibiotic, respectively. We estimated hazard ratios (HRs) with 95% confidence intervals (CIs) by comparing 21-day (days 7-28) risks of ischemic stroke/systemic embolism (SE) following initiation of each exposure. When compared with phenoxymethylpenicillin, dicloxacillin/flucloxacillin was associated with an HR of ischemic stroke/SE of 2.09 (95% CI 1.51-2.90; strongest for dicloxacillin (HR 2.17; 95% CI 1.56-3.02)). Use of an untreated comparator strengthened the association (HR 2.84; 95% CI 1.97-4.09). Dicloxacillin should be used with caution in patients receiving warfarin. This may also apply to flucloxacillin; however, more data on the risks associated with flucloxacillin exposure during warfarin therapy are needed.

Effects of sulfotanshinone sodium injection on the pharmacokinetics and pharmacodynamics of warfarin in rats in vivo

This study was to explore the effects of sulfotanshinone sodium injection (SSI) on the pharmacokinetics and pharmacodynamics of warfarin in rats.The studies of single dose and multiple dose of warfarin were designed to assess the interaction between warfarin and SSI. Rats were divided into different groups randomly and administered with warfarin in the absence or presence of SSI. Prothrombin time (PT) and activated partial thromboplastin time (APTT) values were detected by blood coagulation analyzer, and international normalized ratio (INR) values were calculated. Plasma concentrations of warfarin enantiomers were determined by UPLC-MS/MS method, pharmacokinetic parameters were calculated.The single-dose study demonstrated that the repeated doses of SSI alone had no effect on PT, APTT and INR values, but had a significant effect on PT and INR values produced by a single dose of warfarin, APTT values were unaffected. The C_max, AUC of R-warfarin and S-warfarin were reduced, t_1/2 were shortened. The multiple-dose study showed that PT, APTT, INR values, and the C_max and AUC of R-warfarin and S-warfarin decreased significantly after administration of SSI.The finding implied that SSI could accelerate warfarin metabolism and weaken its anticoagulation. However, human SSI-warfarin interaction studies need to be conducted to confirm this finding.

The antithrombotic activity of the active fractions from the fruits of Celastrus orbiculatus Thunb through the anti-coagulation, anti-platelet activation and anti-fibrinolysis pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Celastrus orbiculatus Thunb (C. orbiculatus) with peel and seeds is mainly composed of flavonoids, sesquiterpenes and tripenes. According to the Traditional Chinese medicine standard of Liaoning province (2009), it has been long used to invigorate blood circulation.

AIM OF THE STUDY

To identify the antithrombus fraction and components of C. orbiculatus, and to investigate the underlying mechanisms.

MATERIALS AND METHODS

The antithrombus effects of C. orbiculatus fractions were evaluated in vitro by plasma recalcification time (PRT). The antithrombus effect of NST-50, the most effective fraction, was further investigated in acute pulmonary embolism (APE) mice and FeCl₃-induced carotid arterial thrombus rats. Bleeding assessment was also carried out to assess the side effects of NST-50. In addition, the content of total flavonoids and active components of NST-50 was also quantified.

RESULTS

Nine flavonoids were detected in NST-50 as main components with the content of 44.70%. Next, NST-50 was found with significant anticoagulation activity by prolonging the plasma recalcification time (PRT), activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) and decreasing the content of fibrinogen (FIB). Furthermore, NST-50 administration markedly suppressed the level of TXB₂ and PAI-1, while significantly up-regulated the level of 6-keto-PGF_1a and t-PA (p < 0.05).

CONCLUSION

The results demonstrated that NST-50 could be valuable in clinical application against acute coronary syndrome, venous thromboembolisms and cerebrovascular thrombosis. It was possible that the anticoagulation action of NST-50 could be related to the regulation of TXA₂ - PGI₂ and t-PA - PAI-1 pairs.

Status of international normalized ratio control and treatment patterns in patients with nonvalvular atrial fibrillation taking vitamin K antagonist with or without antiplatelet therapy: Results from KORAFII registry

BACKGROUND

Studies have shown that the concomitant use of a vitamin K antagonist (VKA) and an antiplatelet (APL) drug increased the bleeding risk and was less effective at preventing ischemic events. This study aimed to investigate the control status of international normalized ratio (INR) and the discontinuation rate of a VKA in patients taking VKA plus an APL drug compared with those taking a VKA alone.

METHODS

Data were extracted from the KORean Atrial Fibrillation Investigation II registry, a multicenter noninterventional prospective observational study. Nonvalvular atrial fibrillation (NVAF) patients with CHADS 2 scores ≥ 1 who newly started (within 3 months) a VKA were enrolled and followed up for 1 year.

RESULTS

A total of 866 NVAF patients (mean age, 67.7 years; 60.3% men) without a bleeding history were divided into the VKA+APL (n = 229) and VKA alone (n = 637) groups. During follow-up, mean INR level was lower in the VKA+APL group than in the VKA alone group (1.7 ± 0.8 vs 1.9 ± 0.9, P = 0.0005). INR levels were poorly controlled in both groups (66.1% and 64.7%, respectively). Patients in the VKA+APL group more frequently discontinued VKA than patients in the VKA alone group (28.8% vs 24.2%, P = 0.045). Major causes of VKA discontinuation were uncontrolled INR level and patient dissatisfaction or concerns.

CONCLUSIONS

The conditions of NVAF patients were inadequately controlled with VKA with or without an APL. These findings suggest that other antithrombotic treatment options are warranted in NVAF patients to achieve INR control.

Initial rivaroxaban dosing in patients with atrial fibrillation

Background

Rivaroxaban is a non‐vitamin K oral anticoagulant and has been approved for prevention of stroke and systemic embolism in patients with non‐valvular atrial fibrillation (AF). Current labeling recommends 20 mg once a day (q.d.) as a standard dose and a reduced dose of 15 mg q.d. in patients with renal impairment.

Hypothesis

The aim of this study was to analyze the adherence to current labeling concerning initial rivaroxaban dosing and to determine whether potential lack of such adherence is medically justified.

Methods

Patients with AF initiated on rivaroxaban between January 1, 2016 and January 31, 2017, were identified in the Heart Center Leipzig database. Health records were screened to identify prescribed rivaroxaban dose, presence or absence of renal impairment, patient characteristics, further dosing‐relevant diagnoses and co‐medication with antiplatelet drugs and non‐vitamin K oral anticoagulants (NOACs).

Results

We identified a total of 378 consecutive patients. In 282 cases (74.6%), rivaroxaban was prescribed in a standard dose and in 96 (25.4%) in a reduced dose. Out of 96 patients receiving a reduced dose, 50 (52.1%) did not meet labeling criteria for dose reduction. In uni‐ and multivariate regression analysis, estimated glomerular filtration rate (eGFR) (odds ratio [OR] 0.34, 95% confidence interval [CI] 0.12‐0.95, P = .04) was the only independent predictor of rivaroxaban underdosage.

Conclusions

In clinical practice, rivaroxaban dosing is frequently incoherent with labeling. In this study, rivaroxaban was often administered underdosed. Potentially inappropriate dose reduction was significantly associated with eGFR, the same factor that is used as criterion for dose adjustment.

Effectiveness and Safety of Off-Label Dose-Reduced Direct Oral Anticoagulants in Atrial Fibrillation

BACKGROUND

Direct oral anticoagulants (DOACs) reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation but may result in serious bleeding complications. Off-label dose-reduced use of DOACs to mitigate bleeding is common in routine clinical practice although data about its consequences on patient outcomes are limited. Therefore, our objective was to evaluate the effectiveness and safety of off-label dose-reduced vs per-label standard-dose DOAC treatment.

METHODS

The study cohort included newly diagnosed patients with nonvalvular atrial fibrillation that had initiated DOAC therapy between 2011 and 2017 in Clalit Health Services (Tel Aviv, Israel). Effectiveness was defined as the composite outcome of all-cause mortality, stroke, or myocardial infarction. The safety outcome was defined as bleeding events requiring hospitalization. Patients were followed until March 30, 2018 or until occurrence of an outcome event. Hazard ratios (HR) were adjusted for 21 variables, including comorbidities, concomitant medications, and socioeconomic factors, using multivariate regression.

RESULTS

A total of 8425 patients met the study criteria; 5140 (61%) patients were treated with DOACs at per-label dosing and 3285 (39%) patients were treated with off-label dose-reduced DOAC. Off-label dose-reduced treatment was associated with a higher rate of the composite effectiveness outcome: adjusted HR 1.57 (95% confidence interval, 1.34-1.83; P < .001) and a higher rate of bleeding: adjusted HR 1.63 (95% confidence interval, 1.14-2.34; P = .008).

CONCLUSIONS

Almost 4 of 10 patients were treated with off-label dose-reduced DOAC, which was associated with reduced effectiveness without a safety benefit. Compliance with per-label dosage may significantly improve outcomes of this population.

Massive Hyphaema Following Laser Iridotomy in a Patient on Dual Antiplatelet Therapy (Aspirin plus Ticagrelor): Case report and literature review

Massive hyphaema presentation after a laser iridotomy is very rare. We report a 63-year-old man with ischaemic heart disease on dual antiplatelet therapy (aspirin plus ticagrelor) who was diagnosed as a primary angle-closure suspect and was to undergo a neodymium-doped yttrium aluminium garnet laser iridotomy at Centro Oftalmológico Virgilio Galvis, Floridablanca, Colombia in 2016. While performing the iridotomy in the left eye, active bleeding occurred that finally filled approximately 75% of the anterior chamber. Intraocular pressure (IOP) increased to 62 mmHg. Mannitol and a topical dorzolamide/timolol were used to control the increase in IOP. The hyphaema slowly resolved over the following week without sequelae. This case revealed that massive hyphaema can complicate laser iridotomy in patients on dual antiplatelet therapy, although this is rare. Therefore, if patients are taking aspirin and ticagrelor, it would be advisable to stop the second medication if possible. In addition, sequential application of photocoagulation and photodisruption lasers might diminish the risk of significant bleeding.

Occurrence of Antithrombotic Related Adverse Events in Hospitalized Patients: Incidence and Clinical Context between 2008 and 2016

Antithrombotic drugs are consistently involved in medication-related adverse events (MRAEs) in hospitalized patients. We aimed to estimate the antithrombotic-related adverse event (ARAE) incidence between 2008 and 2016 and analyse their clinical context in hospitalized patients in The Netherlands. A post-hoc analysis of three national studies, aimed at adverse event (AE) identification, was performed. Previously identified AEs were screened for antithrombotic involvement. Crude and multi-level, case-mix adjusted ARAE and MRAE incidences were calculated. Various contextual ARAE characteristics were analysed. ARAE incidence between 2008 and 2016 decreased significantly in in-hospital deceased patients from 1.20% (95% confidence interval (CI): 0.63-2.27%) in 2008 to 0.54% (95% CI: 0.27-1.11%) in 2015/2016 (p = 0.02). In discharged patients ARAE incidence remained stable. By comparison, overall MRAE incidence remained stable for both deceased and discharged patients. Most ARAEs involved Vitamin-K antagonists (VKAs). Preventable ARAEs occurred more during weekends and with increasing multidisciplinary involvement. Antiplatelet and combined antithrombotic use seemed to be increasingly involved in ARAEs over time. ARAE incidence declined by 55% in deceased patients between 2008 and 2016. Opportunities for improving antithrombotic safety should target INR monitoring and care delivery aspects such as multidisciplinary involvement and weekend care. Future ARAE monitoring for the involvement of antiplatelet, combined antithrombotic and direct oral anticoagulant (DOAC) use is recommended.

The inhibitory effect of tachyplesin I on thrombosis and its mechanisms

Thrombotic diseases are major cause of cardiovascular diseases. This study was designed to investigate the effect of tachyplesin I on platelet aggregation and thrombosis. Platelet aggregation was analysed with a whole blood aggregometer. The mice were employed to investigate the effect of tachyplesin I on thrombosis in vivo. Tachyplesin I inhibited thrombin-induced platelet aggregation in a dose-dependent manner. Furthermore, tachyplesin I significantly reduced thrombosis in carrageenan-induced tail thrombosis model by intraperitoneal injection (0.1, 0.2 or 0.4 mg/kg) or intragastric administration (15, 30 or 60 mg/kg). Tachyplesin I also prolonged the bleeding time (BT) and clotting time (CT). The results revealed that tachyplesin I inhibited platelet aggregation and thrombosis by interfering the PI3K/AKT pathway. Tachyplesin I did not show significantly toxicity to mice under 300 mg/kg via intravenous injection. The results show that tachyplesin I inhibits thrombosis and has low toxicity. It is suggested that tachyplesin I has the potential to develop a new anti-thrombotic drug.

Evaluation of a prescription support-tool for chronic management of oral antithrombotic combinations in adults using clinical vignettes: protocol of a randomised controlled trial

INTRODUCTION

Improving the appropriateness of prescriptions of oral antithrombotic (AT) drugs, especially AT combinations, is crucial because these drugs are implicated in bleeding events. We developed a prescription support-tool synthesising guidelines on chronic management of oral AT combinations. Our main objective is to assess the impact of this tool on improving the prescription of oral ATs to comply with guidelines.

METHODS AND ANALYSIS

A randomised controlled trial will be conducted among French general practitioners and cardiologists involved in outpatient settings. Physicians will be invited to participate to an online survey by email via physician associations, social networks or word of mouth. They will be randomised to two arms: the experimental arm (access to the prescription support-tool) or the control arm (no prescription support-tool). Then, all participants will be presented three different clinical vignettes illustrating outpatient clinical situations and will be asked to propose prescriptions for each vignette (number of ATs, type, dosage and duration). A computer-generated randomisation scheme implemented in the online survey will be used to allocate physicians to the experimental or control arm and then stratified by medical specialty. The primary outcome will be fully appropriate prescription of oral ATs ie, that comply with the guidelines in terms of number of drugs, drug class, dosage and duration. To demonstrate a 5% increase in this proportion, we will need to include a minimum of 230 physicians per arm. A logistic mixed model with a clinical vignette-effect and a physician-effect nested in the arm of the study will be used.

ETHICS AND DISSEMINATION

The Institutional Review Board of Inserm (IRB00003888) approved our research project (no. 18-492). If the prescription support-tool improves the prescription of oral ATs, we will create an interactive web tool and will assess its impact in terms of clinical outcomes in real-life.

TRIAL REGISTRATION NUMBER

NCT03630874; Pre-results.

Perioperative Considerations in the Management of Anticoagulation Therapy for Patients Undergoing Surgery

PURPOSE OF REVIEW

As ambulatory surgery has become increasingly more common, the appropriate management of anticoagulation therapy in patients undergoing invasive procedures has become progressively more relevant to healthcare professionals. The purpose of this literature review is to provide an overview of current common anaticoagulants and their pharmacological properties and to evaluate recent relevant literature and bridging therapy and provide recommendations on risk-guided therapy.

RECENT FINDINGS

With the development of new drugs and the advancing study and practice of anticoagulation use, clinicians must keep up-to-date on the optimal management of patients requiring anticoagulation. NOACs and warfarin continue to be the mainstays of treatment, with varying timelines regarding when to hold administration of the different agents within the perioperative period. There are numerous factors that are considered in patients with multiple comorbidities including the risk for stroke on long-term anticoagulation and risk for thromboembolism, particularly in the perioperative setting when certain medication regimens may be altered and/or briefly held. There is ongoing investigation whether certain NOACs have more efficacy or greater safety profiles, depending on the degree of surgical intervention.

A prescription support-tool for chronic management of oral antithrombotic combinations in adults based on a systematic review of international guidelines

BACKGROUND

Oral antithrombotic (AT) drugs, which include antiplatelet and anticoagulant therapies, are widely implicated in serious preventable bleeding events. Avoiding inappropriate oral AT combinations is a major concern. Numerous practical guidelines have been released; a document to enhance prescriptions of oral AT combinations for adults would be of great help.

OBJECTIVE

To synthesize guidelines on the prescription of oral AT combinations in adults and to create a prescription support-tool for clinicians about chronic management (≥ one month) of oral AT combinations.

METHODS

A systematic review of guidelines published between January 2012 and April 2017, in English or in French, from Trip database, Guideline International Network and PubMed, dealing with the prescription of oral ATs in adults was conducted. In-hospital management of ATs, bridging therapy and switches of ATs were not considered. Some specific topics requiring specialized follow-up (cancer, auto-immune disease, haemophilia, HIV, paediatrics and pregnancy) were excluded. Last update was made in November 2018.

RESULTS

A total of 885 guidelines were identified and 70 met the eligibility criteria. A prescription support-tool summarizing medical conditions requiring chronic management of oral AT combinations in adults with drug types, dosage and duration, on a double-sided page, was provided and tested by an external committee of physicians. The lack of specific guidelines for old people (age 75 years and older) is questioned considering the specific vulnerability of this age group to serious bleedings.

CONCLUSIONS

Recommendations on prescriptions about chronic management of oral AT combinations in adults were mainly consensual but dispersed in numerous guidelines according to the medical indication. We provide a prescription support-tool for clinicians. Further studies are needed to assess the impact of this tool on appropriate prescribing and the prevention of serious adverse drug events.

Recent strategies on targeted delivery of thrombolytics

Thrombus formed in blood vessel is a progressive process, which would lead to life-threatening thrombotic diseases such as ischemic stroke. Unlike other diseases, the recognition of thrombus is usually in the late stage where blood vessels are largely blocked. So acute thrombotic diseases have a narrow therapeutic window, and remain leading causes of morbidity and mortality, whereas current thrombolysis therapy has limited therapeutic effects and bleeding complications. Thrombolytic agents in unwanted sites would cause hemorrhage due to the activation of plasminogen. Moreover, untargeted thrombolysis therapy require large amounts of thrombolytic agents, which in return would enhance hemorrhage risk. To improve the efficiency while minimizing the adverse effects of traditional thrombolysis therapy, novel drug delivery systems have been investigated. Various targeting strategies including ultrasound and magnetic field directed targeting, and specific binding, have been designed to deliver thrombolytic drugs to the thrombotic sites. These strategies demonstrate promising results in reducing bleeding risk as well as allowing less dosage of thrombolytic drugs with lowered clot lysis time. In this review, we discuss recent progress on targeted delivery of thrombolytics, and summarize treatment advantages and shortcomings, potentially helping to further promote the development of targeted thrombolysis.

The Effects of Warfarin on the Pharmacokinetics of Senkyunolide I in a Rat Model of Biliary Drainage After Administration of Chuanxiong

The aim of this study was to elucidate the effects of warfarin on senkyunolide I in a rat model of biliary drainage after oral administration Chuanxiong extract based on pharmacokinetics. Thirty-two rats were randomly divided into four groups: CN, healthy rats after a single administration of Chuanxiong; CO, rats with biliary drainage after a single administration of Chuanxiong; WCN, healthy rats after the administration of Chuanxiong and warfarin; WCO, rats with biliary drainage after the administration of Chuanxiong and warfarin. A series of blood samples were collected at different time points before and after oral administration. An ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) method for quantification of the main components of Chuanxiong and methyclothiazide (internal standard) have been established. The validated method was successfully applied to a comparative pharmacokinetics study. After calculated by the DAS 2.1.1 software, the pharmacokinetics parameters of senkyunolide I showed a significant difference between the CN and CO groups, the AUC_0-t, and C_max of CO group increased by 5.45, 4.02 folds, respectively. There was a significant difference between the WCO and WCN groups, the T_max of WCO group prolonged 67%; compared to the CN group, the AUC_0-t, and C_max of WCN group raised 4.84, 3.49 folds, respectively; the T_max and C_max between the CO and WCO groups also showed a significant difference. The drug warfarin significantly affected the senkyunolide I disposition, which partly due to its enterohepatic circulation process in rat plasma after oral administration of Chuanxiong. The present study highlights an urgent evidence for drug-herb interactions.

Anti-aggregation effect on platelets of Indiplon a hypnotic sedative non-benzodiazepine drug

Cardiovascular diseases are one of the main public health problems, and many of them, their pathophysiology involves alterations in platelet activity. Platelet activation is an essential event that is regulated by the intracellular concentrations of Ca2+ and cAMP. Interestingly, it has been shown that the activation of adenosine A2A receptors increases cAMP levels and produces the inhibition of platelet aggregation, which appears as a potential target for regulation of platelet activity. Therefore, we tried to activate A2A receptors using Indiplon, a drug developed for the treatment of insomnia, and analyze its effect on platelet activity in vitro. Our results indicate that Indiplon is able to interact in silico with the adenosine A2A receptor (ΔG_bind of -73.321 kcal/mol, similar to that obtained with adenosine), which is involved in the regulation of platelet cAMP levels. In functional studies using PRP, a reduction in platelet aggregation induced by ADP was observed in the presence of Indiplon at 500 μM with a percentage of inhibition 70%, where the use of specific inhibitors (ZM241385 and MSX-2) of the A2A receptor also blocked these effects reducing the percentage of inhibition to 41% and 34.1%, respectively. Also, the use of Indiplon produced a decrease in the expression in the membrane of P-selectin. Thus, Indiplon acts as an A2A receptor agonist and whose activation results in inhibition of platelet aggregation and activation, showing a possible cardiovascular protective role.

Candidate gene and pathway analyses identifying genetic variations associated with prasugrel pharmacokinetics and pharmacodynamics

AIM

We aimed to investigate the genetic polymorphisms and pharmacogenetic variability associated with the pharmacodynamics (PD) and pharmacokinetics (PK) of prasugrel, in healthy Han Chinese subjects.

PATIENTS & METHODS

Healthy, native, Han Chinese subjects (n = 36) aged 18 to 45 years with unknown genotypes were included. All subjects received a loading dose (LD) on day 1 and a maintenance dose (MD) from day 2 until day 11. Candidate gene association and gene-set analysis of biological pathways related to prasugrel and platelet activity were analyzed.

RESULTS

28 SNPs of 17 candidate genes previously associated with prasugrel or platelet activity were selected after a literature search. In the 30 mg LD groups (n = 24), ITGA2-rs28095 was found to be significantly associated with the P2Y12 reaction unit (PRU) value at 24 h after the LD (p = 0.015). 165 study genes related to platelet activation-related processes and prasugrel activity were selected from the MSigDB database, including curated gene sets from KEGG, Bio Carta, and Gene Cards. 14 SNPs of 9 genes were found to be significantly correlated both at 24 h and 12 days after LD: ADAMTSL1, PRKCA, ITPR2, P2RY12, P2RY14, PLCB4, PRKG1, ADCY1, and LYN. Seven SNPs of 6 protein-coding genes associated with area under the concentration-time curve (AUC0-tlast) were significantly identified among the 47 selected genes, including ADAMTSL1, CD36, P2RY1, PCSK9, PON1, and SCD.

CONCLUSION

These results show that genetic variation affects the PK and PD of prasugrel in normal individuals. Further studies with larger sample sizes are required to explore whether the SNPs are associated only with prasugrel activity or also with cardiovascular events and all-cause mortality.

The impact of R353Q genetic polymorphism in coagulation factor VII on the initial anticoagulant effect exerted by warfarin

BACKGROUND

The initial rise in INR following warfarin is attributed to rapid decline in coagulation factor VII (F7). The R353Q polymorphism in F7 accounts for approximately 1/3 of the variability in F7 activity (FVIIc).

OBJECTIVE

Evaluate the role of R353Q in the initial response to warfarin.

METHODS

Twenty-eight healthy, males, carrying CYP2C9*1/*1 (n = 14), CYP2C9*1/*2 (n = 4) or CYP2C9*1/*3 (n = 10) genotypes, received single 20 mg warfarin. S&R-warfarin concentrations, INR, and FVIIc were monitored periodically for 7 days.

RESULTS

Baseline and maximal INR were 5.6% and 33.5% higher among carriers of the RQ (n = 12) as compared with those carrying the RR (n = 16) genotype (p = 0.032, p = 0.003, respectively). Baseline and nadir FVIIc were 21.6% and 42.0% lower among subjects carrying the RQ as compared with carriers of the RR genotype (p = 0.001, p = 0.007 respectively). In multiple regression analysis, R353Q predicted 36.6% of the variability in peak INR whereas 20.2%, 9.9%, and 5.9% were attributed to VKORC1 genetic polymorphism, cholesterol concentration, and S Warfarin concentration after 24 h, respectively.

CONCLUSIONS

R353Q genetic polymorphism plays a key role in determining the initial response to warfarin. The incorporation of this genetic variant into warfarin loading algorithm should be further investigated.

Interaction between warfarin and cannabis

Delta-9-tetrahydrocannabinol (THC), the main psychoactive cannabinoid in cannabis, may inhibit the cytochrome P450 enzyme CYP2C9. Consequently, cannabis use might infer a risk of drug-drug interaction with substrates for this enzyme, which includes drugs known to have a narrow therapeutic window. In this study, we describe a case report of a 27-year-old man treated with warfarin due to mechanical heart valve replacement who presented with elevated international normalized ratio (INR) value (INR = 4.6) following recreational cannabis use. We conducted a review of the available literature, using the PubMed and EMBASE databases while following PRISMA guidelines. Following screening of 85 articles, three eligible articles were identified, including one in vitro study and two case reports. The in vitro study indicated that THC inhibits the CYP2C9-mediated metabolism of warfarin. One case study reported of a man who on two occasions of increased marijuana use experienced INR values above 10 as well as bleeding. The other case study reported of a patient who initiated treatment with a liquid formulation of cannabidiol for the management of epilepsy, ultimately necessitating a 30% reduction in warfarin dose to maintain therapeutic INR values. The available, although sparse, data suggest that use of cannabinoids increases INR values in patients receiving warfarin. Until further data are available, we suggest patients receiving warfarin be warned against cannabis use.

The critical interaction between valproate sodium and warfarin: case report and review

BACKGROUND

Valproic acid (VPA) and warfarin are commonly prescribed for patients with epilepsy and concomitant atrial fibrillation (AF). When VPA and warfarin are prescribed together, clinically important interactions may occur. VPA may replace warfarin from the protein binding sites and result in an abnormally increased anticoagulation effect. This is commonly underrecognized.

CASE PRESENTATION

In our case, we report a 78-year-old woman with a glioma who presented with status epilepticus. The patient was on warfarin to prevent cardiogenic embolism secondary to AF. Intravenous loading dose of VPA was administered, but international normalized ratio (INR) increased significantly to 8.26. Intravenous vitamin K1 was then given and the patient developed no overt bleeding during the hospitalization.

CONCLUSION

By reviewing the literature and discussing the critical interaction between valproate sodium and warfarin, we conclude that intravenous VPA and the co-administrated warfarin may develop critical but underrecognized complications due to effects on the function of hepatic enzymes and displacement of protein binding sites.

Usefulness and Safety of Rivaroxaban in Patients Following Isolated Mitral Valve Replacement With a Mechanical Prosthesis

Rivaroxaban has previously been tested in experimental and animal models with encouraging results. We prospectively selected seven patients between May 2017 and January 2018 who underwent isolated mitral valve replacement with a mechanical prosthesis and had unstable INR control at least 3 months after surgery. An intervention of rivaroxaban 15mg was then administered twice daily for a period of 90days. No patient presented intracardiac thrombus, reversible ischemic neurological deficit, ischemic or hemorrhagic stroke, and hospitalization or death during 3 months of follow-up. Two patients eradicated the presence of spontaneous echo contrast. Mean and peak pressure gradients, peak velocity, effective orifice area, and PHT were similar before and after the intervention. In conclusion, the use of rivaroxaban for 90days in seven patients after replacement of mitral valve with the mechanical prosthesis did not present thromboembolic or bleeding events (NCT02894307).