Is platelet inhibition due to thienopyridines increased in elderly patients, in patients with previous stroke and patients with low body weight as a possible explanation of an increased bleeding risk?

Background The TRITON-TIMI 38 study has identified three subgroups of patients with a higher risk of bleeding during treatment with the thienopyridine prasugrel: patients with a history of stroke or transient ischaemic attack (TIA), patients ≥75 years and patients with a body weight <60 kg. However, the underlying pathobiology leading to this increased bleeding risk remains to be elucidated. The higher bleeding rate may be due to a stronger prasugrelinduced inhibition of platelet aggregation in these subgroups. The aim of the present study was to determine whether on-treatment platelet reactivity is lower in these risk subgroups as compared with other patients in a large cohort on the thienopyridine clopidogrel undergoing elective coronary stenting. Methods A total of 1069 consecutive patients were enrolled. On-clopidogrel platelet reactivity was measured in parallel by light transmittance aggregometry, the Verify- Now®P2Y12 assay and the PFA-100 collagen/ADP cartridge. Results Fourteen patients (1.5%) had a prior history of stroke or TIA, 138 patients (14.5%) were older than 75 years and 30 patients (3.2%) had a body weight <60 kg. Age ≥75 years and a history of stroke were independent predictors of a higher on-treatment platelet reactivity. In contrast, a body weight <60 kg was significantly associated with a lower on-treatment platelet reactivity. Conclusion In two high-risk subgroups for bleeding, patients ≥75 years and patients with previous stroke, onclopidogrel platelet reactivity is increased. In contrast, in patients with a low body weight, on-clopidogrel platelet reactivity is decreased, suggesting that a stronger response to a thienopyridine might only lead to more bleeds in patients with low body weight

Discovery of 1,3-Diaminobenzenes as Selective Inhibitors of Platelet Activation at the PAR1 Receptor

A high-throughput screen of the NIH-MLSMR compound collection, along with a series of secondary assays to identify potential targets of hit compounds, previously identified a 1,3-diaminobenzene scaffold that targets protease-activated receptor 1 (PAR1). We now report additional structure–activity relationship (SAR) studies that delineate the requirements for activity at PAR1 and identify plasma-stable analogues with nanomolar inhibition of PAR1-mediated platelet activation. Compound 4 was declared as a probe (ML161) with the NIH Molecular Libraries Program. This compound inhibited platelet aggregation induced by a PAR1 peptide agonist or by thrombin but not by several other platelet agonists. Initial studies suggest that ML161 is an allosteric inhibitor of PAR1. These findings may be important for the discovery of antithrombotics with an improved safety profile

High platelet reactivity in patients with acute coronary syndromes undergoing percutaneous coronary intervention: Randomised controlled trial comparing prasugrel and clopidogrel

Background: Prasugrel is more effective than clopidogrel in reducing platelet aggregation in acute coronary syndromes. Data available on prasugrel reloading in clopidogrel treated patients with high residual platelet reactivity (HRPR) i.e. poor responders, is limited. Objectives: To determine the effects of prasugrel loading on platelet function in patients on clopidogrel and high platelet reactivity undergoing percutaneous coronary intervention for acute coronary syndrome (ACS). Patients: Patients with ACS on clopidogrel who were scheduled for PCI found to have a platelet reactivity ≥40 AUC with the Multiplate Analyzer, i.e. “poor responders” were randomised to prasugrel (60 mg loading and 10 mg maintenance dose) or clopidogrel (600 mg reloading and 150 mg maintenance dose). The primary outcome measure was proportion of patients with platelet reactivity <40 AUC 4 hours after loading with study medication, and also at one hour (secondary outcome). 44 patients were enrolled and the study was terminated early as clopidogrel use decreased sharply due to introduction of newer P2Y12 inhibitors. Results: At 4 hours after study medication 100% of patients treated with prasugrel compared to 91% of those treated with clopidogrel had platelet reactivity <40 AUC (p = 0.49), while at 1 hour the proportions were 95% and 64% respectively (p = 0.02). Mean platelet reactivity at 4 and 1 hours after study medication in prasugrel and clopidogrel groups respectively were 12 versus 22 (p = 0.005) and 19 versus 34 (p = 0.01) respectively. Conclusions: Routine platelet function testing identifies patients with high residual platelet reactivity (“poor responders”) on clopidogrel. A strategy of prasugrel rather than clopidogrel reloading results in earlier and more sustained suppression of platelet reactivity. Future trials need to identify if this translates into clinical benefit

P2Y12 platelet inhibition in clinical practice

Platelet adhesion, activation and aggregation play a pivotal role in atherothrombosis. Intracoronary atherothrombosis is the most common cause of the development of acute coronary syndrome (ACS), and plays a central role in complications occurring around percutaneous coronary intervention (PCI) including recurrent ACS, procedure-related myocardial infarction or stent thrombosis. Inhibition of platelet aggregation by medical treatment impairs formation and progression of thrombotic processes and is therefore of great importance in the prevention of complications after an ACS or around PCI. An essential part in the platelet activation process is the interaction of adenosine diphosphate (ADP) with the platelet P2Y12 receptor. The P2Y12 receptor is the predominant receptor involved in the ADP-stimulated activation of the glycoprotein IIb/IIIa receptor. Activation of the glycoprotein IIb/IIIa receptor results in enhanced platelet degranulation and thromboxane production, and prolonged platelet aggregation. The objectives of this review are to discuss the pharmacological limitations of the P2Y12 inhibitor clopidogrel, and describe the novel alternative P2Y12 inhibitors prasugrel and ticagrelor and the clinical implications of the introduction of these new medicines

Effect of Dapagliflozin on Cardiovascular Outcomes According to Baseline Kidney Function and Albuminuria Status in Patients With Type 2 Diabetes A Prespecified Secondary Analysis of a Randomized Clinical Trial

ImportanceSodium-glucose cotransporter 2 inhibitors, such as dapagliflozin, promote renal glucose excretion and reduce cardiovascular (CV) deaths and hospitalizations for heart failure (HHF) among patients with type 2 diabetes. The relative CV efficacy and safety of dapagliflozin according to baseline kidney function and albuminuria status are unknown.ObjectiveTo assess the CV efficacy and safety of dapagliflozin according to baseline estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (UACR).Design, setting, and participantsThis secondary analysis of the randomized clinical trial Dapagliflozin Effect on Cardiovascular Events-Thrombolysis in Myocardial Infarction 58 compared dapagliflozin vs placebo in 17 160 patients with type 2 diabetes and a baseline creatinine clearance of 60 mL/min or higher. Patients were categorized according to prespecified subgroups of baseline eGFR (InterventionsDapagliflozin vs placebo.Main outcomes and measuresThe dual primary end points were major adverse cardiovascular events (myocardial infarction, stroke, and CV death) and the composite of CV death or HHF.ResultsAt baseline, 1265 patients (7.4%) had an eGFR below 60 mL/min/1.73 m2, and 5199 patients (30.9%) had albuminuria. Among patients having data for both eGFR and UACR, 10 958 patients (65.1%) had an eGFR equal to or higher than 60 mL/min/1.73 m2 and an UACR below 30 mg/g (mean [SD] age, 63.7 [6.7] years; 40.1% women), 5336 patients (31.7%) had either an eGFR below 60 mL/min/1.73 m2 or albuminuria (mean [SD] age, 64.1 [7.1] years; 32.6% women), and 548 patients (3.3%) had both (mean [SD] age, 66.8 [6.9] years; 30.5% women). In the placebo group, patients with more CKD markers had higher event rates at 4 years as assessed using the Kaplan-Meier approach for the composite of CV death or HHF (3.9% for 0 markers, 8.3% for 1 marker, and 17.4% for 2 markers) and major adverse cardiovascular events (7.5% for 0 markers, 11.6% for 1 marker, and 18.9% for 2 markers). Estimates for relative risk reductions for the composite of CV death or HHF and for major adverse cardiovascular events were generally consistent across subgroups (both P > .24 for interaction), although greater absolute risk reductions were observed with more markers of CKD. The absolute risk difference for the composite of CV death or HHF was greater for patients with more markers of CKD (0 markers, -0.5%; 1 marker, -1.0%; and 2 markers, -8.3%; P = .02 for interaction). The numbers of amputations, cases of diabetic ketoacidosis, fractures, and major hypoglycemic events were balanced or numerically lower with dapagliflozin compared with placebo for patients with an eGFR below 60 mL/min/1.73 m2 and an UACR of 30 mg/g or higher.Conclusions and relevanceThe effect of dapagliflozin on the relative risk for CV events was consistent across eGFR and UACR groups, with the greatest absolute benefit for the composite of CV death or HHF observed among patients with both reduced eGFR and albuminuria.Trial registrationClinicalTrials.gov Identifier: NCT01730534

GPIIb/IIIa Receptor Antagonism Using Small Molecules Provides no Additive Long-Term Protection after Percutaneous Coronary Intervention as Compared to Clopidogrel Plus Aspirin

Background: There is some controversy as to whether tirofiban or eptifibatide, two small anti-aggregating drugs (AAD), may reduce the incidence of composite ischemic events within one year in patients undergoing percutaneous coronary intervention (PCI) in the real clinical world. Methods: We compared consecutive patients on oral double AAD (with clopidogrel and aspirin) who underwent PCI (n=207) and patients who were on single AAD and received a second AAD, just prior to PCI, and either high-dose tirofiban or double-bolus eptifibatide (double AAD plus small molecules group, n=666). The primary end point (incidence of composite ischemic events within one year) included death, acute myocardial infarction, unstable angina, stent thrombosis or repeat PCI or coronary bypass surgery (related to the target vessel PCI failure) and was modelled by Cox's regression. Results: There were 89 composite ischemic events: 24 (11.6%) in double AAD alone and 65 (9.8%) in double AAD plus small molecules groups (log-rank test: p=0.36). Incidences by type of ischemic events were similar between the 2 groups. Based on 21 potential covariates fitted simultaneously, adjusted hazard ratios (HR and 95% confidence intervals) showed that age (HR 1.03, 1.01-1.06, p=0.01), diabetes (HR 1.68, 1.01-2.79, p=0.05) and intra aortic balloon pump (HR 5.12, 2.36-11.10, p=0.0001) were significant risk factors whereas thrombolysis by tenecteplase (HR 0.35, 0.13-0.98, p=0.05) and having had hypertension or anti-hypertensive treatment (HR 0.58, 0.36-0.93, p=0.03) were significant protectors for events. Whether small molecules were present provided a non significant additional benefit as compared to double AAD alone (HR 0.83, 0.51-1.36, p=0.46). Pre-PCI CK-MB were not useful to predict events (HR 1.01, 0.99-1.01, p=0.17). Conclusions: In clinical world patients undergoing PCI (rescue plus primary <13%) while on double AAD, based on clopidogrel plus aspirin, small molecules (tirofiban or eptifibatide) provided no additive long-term protection against the occurrence of composite ischemic events whereas thrombolysis by tenecteplase did. © Schiariti et al

Cost-effectiveness Analysis of Rivaroxaban in the Secondary Prevention of Acute Coronary Syndromes in Sweden.

BACKGROUND: Worldwide, coronary heart disease accounts for 7 million deaths each year. In Sweden, acute coronary syndrome (ACS) is a leading cause of hospitalization and is responsible for 1 in 4 deaths. OBJECTIVE: The aim of this analysis was to assess the cost-effectiveness of rivaroxaban 2.5 mg twice daily (BID) in combination with standard antiplatelet therapy (ST-APT) versus ST-APT alone, for the secondary prevention of ACS in adult patients with elevated cardiac biomarkers without a prior history of stroke/transient ischemic attack (TIA), from a Swedish societal perspective, based on clinical data from the global ATLAS ACS 2-TIMI 51 trial, literature-based quality of life data and costs sourced from Swedish national databases. METHODS: A Markov model was developed to capture rates of single and multiple myocardial infarction (MI), ischemic and hemorrhagic stroke, thrombolysis in myocardial infarction (TIMI) major, minor, and "requiring medical attention" bleeds, revascularization events, and associated costs and utilities in patients who were stabilized after an initial ACS event. Efficacy and safety data for the first 2 years came from the ATLAS ACS 2-TIMI 51 trial. Long-term probabilities were extrapolated using safety and effectiveness of acetylsalicylic acid data, which was estimated from published literature, assuming constant rates in time. Future cost and effects were discounted at 3.0%. Univariate and probabilistic sensitivity analyses were conducted. RESULTS: In the base case, the use of rivaroxaban 2.5 mg BID was associated with improvements in survival and quality-adjusted life years (QALYs), yielding an incremental cost per QALY of 71,246 Swedish Krona (SEK) (€8045). The outcomes were robust to changes in inputs. The probabilistic sensitivity analysis demonstrated rivaroxaban 2.5 mg BID to be cost-effective in >99.9% of cases, assuming a willingness-to-pay threshold of SEK 500,000 (€56,458). CONCLUSION: Compared with ST-APT alone, the use of rivaroxaban 2.5 mg BID in combination with ST-APT can be considered a cost-effective treatment option for ACS patients with elevated cardiac biomarkers without a prior history of stroke/TIA in Sweden. FUNDING: Bayer Pharma AG

The Effect of Dapagliflozin on Albuminuria in DECLARE-TIMI 58

OBJECTIVE Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve albuminuria in patients with high cardiorenal risk. We report albuminuria change in the Dapagliflozin Effect on Cardiovascular Events (DECLARE-TIMI 58) cardiovascular outcome trial, which included populations with lower cardiorenal risk. RESEARCH DESIGN AND METHODS DECLARE-TIMI 58 randomized 17,160 patients with type 2 diabetes, creatinine clearance >60 mL/min, and either atherosclerotic cardiovascular disease (CVD; 40.6%) or risk-factors for CVD (59.4%) to dapagliflozin or placebo. Urinary albumin-to-creatinine ratio (UACR) was tested at baseline, 6 months, 12 months, and yearly thereafter. The change in UACR over time was measured as a continuous and categorical variable (15 to = 30 to 300 mg/g) by treatment arm. The composite cardiorenal outcome was a >= 40% sustained decline in the estimated glomerular filtration rate (eGFR) to 15 to 300 mg/g. Measured as a continuous variable, UACR improved from baseline to 4.0 years with dapagliflozin, compared with placebo, across all UACR and eGFR categories (all P = 1 category improvement in UACR was more common in dapagliflozin versus placebo (hazard ratio 1.45 [95% CI 1.35-1.56], P = 30 mg/g (P < 0.0125, P-interaction = 0.033), and the renal-specific outcome was reduced for all UACR subgroups (P < 0.05, P-interaction = 0.480). CONCLUSIONS In DECLARE-TIMI 58, dapagliflozin demonstrated a favorable effect on UACR and renal-specific outcome across baseline UACR categories, including patients with normal albumin excretion. The results suggest a role for SGLT2i also in the primary prevention of diabetic kidney disease

Drug metabolizing enzyme activities versus genetic variances for drug of clinical pharmacogenomic relevance

Enzymes are critically important in the transportation, metabolism, and clearance of most therapeutic drugs used in clinical practice today. Many of these enzymes have significant genetic polymorphisms that affect the enzyme's rate kinetics. Regarding drug metabolism, specific polymorphisms to the cytochrome (CYP) P450 enzyme family are linked to phenotypes that describe reaction rates as "ultra", "intermediate", and "poor," as referenced to "extensive" metabolizers that are assigned to wildtype individuals. Activity scores is an alternate designation that provides more genotype-to-phenotype resolution. Understanding the relative change in enzyme activities or rate of clearance of specific drugs relative to an individual's genotypes is an important component in the interpretation of pharmacogenomic data for personalized medicine. Currently, the most relevant drug metabolizing enzymes are CYP 2D6, CYP 2C9, CYP 2C19, thiopurine methyltransferase (TPMT) and UDP-glucuronosyltransferase (UGT). Each of these enzymes is reactive to a host of different drug substrates. Pharmacogenomic tests that are in routine clinical practice include CYP 2C19 for clopidogrel, TPMT for thiopurine drugs, and UDP-1A1 for irinotecan. Other tests where there is considerable data but have not been widely implemented includes CYP 2C9 for warfarin, CYP 2D6 for tamoxifen and codeine, and CYP 2C19 for the proton pump inhibitors