Drug resistance and pseudoresistance: an unintended consequence of enteric coating aspirin

Should We Use Aspirin or P2Y12 Inhibitor Monotherapy in Stable Ischemic Heart Disease?

PURPOSE OF REVIEW

To summarize the recent evidence and guideline recommendations on aspirin or P2Y12 inhibitor monotherapy in patients with stable ischemic heart disease and provide insights into future directions on this topic, which involves transition to a personalized assessment of bleeding and thrombotic risks.

RECENT FINDINGS

It has been questioned whether the evidence for aspirin as the foundational component of secondary prevention in patients with coronary artery disease aligns with contemporary pharmaco-invasive strategies. The recent HOST-EXAM study randomized patients who had received dual antiplatelet therapy for 6 to 18 months without ischemic or major bleeding events to either clopidogrel or aspirin for a further 24 months, and demonstrated that the patients in the clopidogrel arm had significantly lower rates of both thrombotic and bleeding complications compared to those in the aspirin arm. The patient-level PANTHER meta-analysis showed that in patients with established coronary artery disease, P2Y12 inhibitor monotherapy was associated with lower rates of myocardial infarction, stent thrombosis as well as gastrointestinal bleeding and hemorrhagic stroke compared to aspirin monotherapy, albeit with similar rates of all-cause mortality, cardiovascular mortality and major bleeding. Long-term low-dose aspirin is recommended for secondary prevention in patients with stable ischemic heart disease, with clopidogrel monotherapy being acknowledged as a feasible alternative. Dual antiplatelet therapy for six months after percutaneous coronary intervention remains the standard recommendation for patients with stable ischemic heart disease. However, the duration of dual antiplatelet therapy may be shortened and followed by P2Y12 inhibitor monotherapy or prolonged based on individualized evaluation of the patient's risk profile.

Low-Dose Enteric-Coated and Chewable Aspirin Are Not Equally Effective in Preventing Venous Thromboembolism in Total Knee and Hip Arthroplasty

BACKGROUND

Low-dose aspirin is an effective venous thromboembolism (VTE) prophylactic medication in primary total joint arthroplasty, but the efficacy and safety of the formulations of chewable and enteric-coated aspirin have not been compared. The purpose of this study was to investigate the VTE and gastrointestinal (GI) complication rates of chewable and enteric-coated 81 mg aspirin bis in die for VTE prophylaxis in primary total joint arthroplasty.

METHODS

A retrospective, single-institution cohort study was performed on patients who underwent primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) from 2017 to 2021. Comparisons were made between 4,844 patients who received chewable, noncoated aspirin 81 mg and 4,388 patients who received enteric-coated 81 mg aspirin. Power analysis demonstrated 1,978 and 3,686 patients were needed per group to achieve a power of 80% for 90-day VTE rates (using inferiority testing) and GI complications (using superiority testing), respectively. Patients had similar baseline characteristics. Statistical analyses were done using t-tests and Chi-squared tests, with statistical significance defined as a P value < .05.

RESULTS

There were no significant differences in the incidences of postoperative VTE (0.31% versus 0.55%; P = .111) or GI complications (0.14% versus 0.14%; P = 1.000) between patients who received either chewable or enteric-coated 81 mg aspirin bis in die in the overall comparison that included both THA and TKA patients combined, or THA patients alone. However, the VTE incidence for TKA patients alone was significantly lower with chewable than enteric-coated aspirin (0.22% versus 0.62%; P = .037), with no difference in GI complications (0.13% versus 0.19%; P = .277).

CONCLUSIONS

Low-dose aspirin in enteric-coated formulation is inferior to chewable aspirin for VTE prophylaxis in primary TKA, but not inferior in THA patients. Both formulations have a similar GI complication rate. Therefore, it is reasonable to consider a transition from enteric-coated to uncoated chewable low-dose aspirin.

Appropriate use of antiplatelet medications following transient ischemic attacks and stroke: a 9-year study from the Middle East

Background and purpose

Guidelines recommend that patients with high-risk TIAs and minor strokes presenting within 1-3 days from onset should be offered dual antiplatelet therapy (DAPT). There are little data on real-world adherence to these recommendations. We evaluated the appropriateness of DAPT use in TIA and stroke patients in a prospective database.

Methods

The Qatar Stroke Database began the enrollment of patients with TIAs and acute stroke in 2014 and currently has ~16,000 patients. For this study, we evaluated the rates of guideline-adherent use of antiplatelet treatment at the time of discharge in patients with TIAs and stroke. TIAs were considered high-risk with an ABCD2 score of 4, and a minor stroke was defined as an NIHSS of 3. Patient demographics, clinical features, risk factors, previous medications, imaging and laboratory investigations, final diagnosis, discharge medications, and discharge and 90-day modified Rankin Scale (mRS) were analyzed.

Results

After excluding patients with ICH, mimics, and rare secondary causes, 8,082 patients were available for final analysis (TIAs: 1,357 and stroke: 6,725). In high-risk TIAs, 282 of 666 (42.3%) patients were discharged on DAPT. In patients with minor strokes, 1,207 of 3,572 (33.8%) patients were discharged on DAPT. DAPT was inappropriately offered to 238 of 691 (34.4%) low-risk TIAs and 809 of 3,153 (25.7%) non-minor stroke patients.

Conclusion

This large database of prospectively collected patients with TIAs and stroke shows that, unfortunately, despite several guidelines, a large majority of patients with TIAs and stroke are receiving inappropriate antiplatelet treatment at discharge from the hospital. This requires urgent attention and further investigation.

Effectiveness and Safety of Enteric-Coated vs Uncoated Aspirin in Patients With Cardiovascular Disease: A Secondary Analysis of the ADAPTABLE Randomized Clinical Trial

Importance

Clinicians recommend enteric-coated aspirin to decrease gastrointestinal bleeding in secondary prevention of coronary artery disease even though studies suggest platelet inhibition is decreased with enteric-coated vs uncoated aspirin formulations.

Objective

To assess whether receipt of enteric-coated vs uncoated aspirin is associated with effectiveness or safety outcomes.

Design, Setting, and Participants

This is a post hoc secondary analysis of ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-term Effectiveness), a pragmatic study of 15 076 patients with atherosclerotic cardiovascular disease having data in the National Patient-Centered Clinical Research Network. Patients were enrolled from April 19, 2016, through June 30, 2020, and randomly assigned to receive high (325 mg) vs low (81 mg) doses of daily aspirin. The present analysis assessed the effectiveness and safety of enteric-coated vs uncoated aspirin among those participants who reported aspirin formulation at baseline. Data were analyzed from November 11, 2019, to July 3, 2023.

Intervention

ADAPTABLE participants were regrouped according to aspirin formulation self-reported at baseline, with a median (IQR) follow-up of 26.2 (19.8-35.4) months.

Main Outcomes and Measures

The primary effectiveness end point was the cumulative incidence of the composite of myocardial infarction, stroke, or death from any cause, and the primary safety end point was major bleeding events (hospitalization for a bleeding event with use of a blood product or intracranial hemorrhage). Cumulative incidence at median follow-up for primary effectiveness and primary safety end points was compared between participants taking enteric-coated or uncoated aspirin using unadjusted and multivariable Cox proportional hazards models. All analyses were conducted for the intention-to-treat population.

Results

Baseline aspirin formulation used in ADAPTABLE was self-reported for 10 678 participants (median [IQR] age, 68.0 [61.3-73.7] years; 7285 men [68.2%]), of whom 7366 (69.0%) took enteric-coated aspirin and 3312 (31.0%) took uncoated aspirin. No significant difference in effectiveness (adjusted hazard ratio [AHR], 0.94; 95% CI, 0.80-1.09; P = .40) or safety (AHR, 0.82; 95% CI, 0.49-1.37; P = .46) outcomes between the enteric-coated aspirin and uncoated aspirin cohorts was found. Within enteric-coated aspirin and uncoated aspirin, aspirin dose had no association with effectiveness (enteric-coated aspirin AHR, 1.13; 95% CI, 0.88-1.45 and uncoated aspirin AHR, 0.99; 95% CI, 0.83-1.18; interaction P = .41) or safety (enteric-coated aspirin AHR, 2.37; 95% CI, 1.02-5.50 and uncoated aspirin AHR, 0.89; 95% CI, 0.49-1.64; interaction P = .07).

Conclusions and Relevance

In this post hoc secondary analysis of the ADAPTABLE randomized clinical trial, enteric-coated aspirin was not associated with significantly higher risk of myocardial infarction, stroke, or death or with lower bleeding risk compared with uncoated aspirin, regardless of dose, although a reduction in bleeding with enteric-coated aspirin cannot be excluded. More research is needed to confirm whether enteric-coated aspirin formulations or newer formulations will improve outcomes in this population.

Trial Registration

ClinicalTrials.gov Identifier: NCT02697916.

Pharmacokinetic Study of Enteric-Coated Sustained-Release Aspirin Tablets in Healthy Chinese Participants

Purpose

To study and compare the pharmacokinetic characteristics of enteric-coated sustained-release (EcSr) aspirin tablets with enteric-coated (Ec) aspirin tablets (Bayer S.p.A) in healthy Chinese participants.

Patients and Methods

In this open, randomized, single-dose, three-way, crossover study, 18 healthy participants randomly received 100 mg EcSr tablets pre-prandially (a.c.), EcSr tablets post-prandially (p.c.), or Ec tablets a.c. in each period. The concentrations of acetylsalicylic acid (ASA) and salicylic acid (SA) in plasma were determined by the LC-MS/MS method, and the pharmacokinetic parameters were calculated using WinNonlin (version 8.1).

Results

The essential PK parameters under the three treatment conditions (ie Ec a.c., EcSr a.c. and EcSr p.c.) were as follows: Cmax, ASA: 758.38±455.34, 222.77±98.04 and 194.54±61.19 ng, Tmax, ASA: 6.75(2,16), 4.5(2,11) and 8.25(5,11) h, T1/2, ASA: 0.43±0.08, 1.44±0.59 and 4.32±10.04 h, AUC0-t, ASA: 1008.88±452.27, 918.04±238.40 and 845.55±183.25 h·ng/mL; Cmax, SA: 6409.38±2098.52, 2863.53±679.73 and 2913.75±853.27ng/mL, Tmax, SA: 7.25(2,24), 10(3.5-14) and 10(7,14) h, T1/2, SA: 2.21±0.46, 2.69±0.72 and 3.51±2.06h, AUC0-t, SA: 29,131.41±9376.23, 27,243.97±7465.16, 27,240.25±7444.67 h·ng/mL. When taking EcSr aspirin tablets, the 90% confidence intervals of the geometric mean ratios (pre-prandial/post-prandial) of AUC0-t, ASA and AUC0-∞, ASA, Cmax, SA, AUC0-t, SA and AUC0-∞, SA were within the range of 80.00%-125.00%.

Conclusion

EcSr aspirin tablets showed less inter-individual variation in release and absorption than Ec aspirin tablets, which was well reflected by comparing essential PK parameters. Furthermore, meals had no significant effect on the pharmacokinetics of EcSr aspirin tablets.

Personalized Dual Antiplatelet Therapy in Acute Coronary Syndromes: Striking a Balance Between Bleeding and Thrombosis

PURPOSE OF REVIEW

Dual antiplatelet therapy (DAPT)-aspirin in conjunction with a P2Y12 inhibitor-is the cornerstone of managing patients with acute coronary syndromes post-revascularization, but the clinical response is highly variable, with potentially devastating consequences. Herein, we review the mechanisms underpinning said variability and explore emerging approaches to normalizing therapeutic benefit.

RECENT FINDINGS

The potent P2Y12 inhibitors, prasugrel and ticagrelor, exhibit minimal inter-individual variability, replacing clopidogrel in DAPT and achieving greater rates of therapeutic response. However, these benefits decline in later phases when bleeding risk begins to supersede that of ischemia. Guided de-escalation of P2Y12 inhibition as well as shortening DAPT duration have emerged as strategies that retain antithrombotic efficacy while reducing bleeding risk. Aspirin is the other component of DAPT but is also used in isolation for secondary prevention of thrombotic disease. In contrast to the P2Y12 inhibitors, genetic influences on aspirin non-response appear to be outweighed by a triad of clinical factors: non-adherence, enteric aspirin use, and inappropriate dosing according to bodyweight and BMI. Multiple de-escalation strategies for DAPT have been shown to mitigate bleeding risk, but it remains unclear which approach is ideal, necessitating head-to-head investigations to determine which exhibits the most favorable cost-to-benefit ratio. However, there is likely a role for more than one approach in clinical practice, depending on patient risk profile. Our approach to aspirin use is also in need of reassessment: strategies to improve adherence, avoidance of enteric aspirin in cardiac patients, and dose adjustment according to bodyweight and/or BMI are all likely to improve rates of therapeutic response. Moreover, platelet function testing may have a role in identifying patients expected to benefit from primary prophylactic aspirin.

Pharmacological Efficacy and Gastrointestinal Safety of Different Aspirin Formulations for Cardiovascular Prevention: A Narrative Review

Aspirin inhibits platelet function by irreversibly inhibiting the synthesis of thromboxane A2 (TxA2). Aspirin, at low doses, is widely used for cardiovascular prevention. Gastrointestinal discomfort, mucosal erosions/ulcerations and bleeding are frequent complications of chronic treatment. To reduce these adverse effects, different formulations of aspirin have been developed, including enteric-coated (EC) aspirin, the most widely used aspirin formulation. However, EC aspirin is less effective than plain aspirin in inhibiting TxA2 production, especially in subjects with high body weight. The inadequate pharmacological efficacy of EC aspirin is mirrored by lower protection from cardiovascular events in subjects weighing >70 kg. Endoscopic studies showed that EC aspirin causes fewer erosions of the gastric mucosa compared to plain aspirin (which is absorbed in the stomach) but causes mucosal erosions in the small intestine, where it is absorbed. Several studies demonstrated that EC aspirin does not reduce the incidence of clinically relevant gastrointestinal ulceration and bleeding. Similar results were found for buffered aspirin. Although interesting, the results of experiments on the phospholipid-aspirin complex PL2200 are still preliminary. Considering its favorable pharmacological profile, plain aspirin should be the preferred formulation to be used for cardiovascular prevention.

Fifty years with aspirin and platelets

In 2021, we reached the 50th anniversary of the publication of Sir John Vane's seminal paper in Nature New Biology describing the experiments supporting his mechanistic hypothesis that inhibition of prostaglandin synthesis might explain the main pharmacological effects of aspirin and aspirin-like drugs, that is, reduction in pain, fever and inflammation. Bengt Samuelsson's subsequent discoveries elucidating the cyclooxygenase pathway of platelet arachidonic acid metabolism motivated my research interest towards measuring platelet thromboxane A₂ biosynthesis as a tool to investigate the clinical pharmacology of cyclooxygenase inhibition by aspirin in health and disease. What followed was a long, winding road of clinical research leading to the characterization of low-dose aspirin as a life-saving antiplatelet drug that still represents the cornerstone of antithrombotic therapy. Having witnessed and participated in these 50 years of aspirin research, I thought of providing a personal testimony of how things developed and eventually led to a remarkable success story of independent research.

[Modern strategies for the management of patients who have suffered ischemic stroke or transient ischemic attack]

Modern strategies for secondary prevention of ischemic stroke (IS) are based on long-term use of drugs from three main pharmaceutical groups (antihypertensive, lipid-lowering and antithrombotic drugs). In practical terms, the most difficult thing for a practitioner is the choice of antithrombotic therapy with anticoagulants or antiplatelet agents. Antithrombotic therapy for patients with acute cerebrovascular accidents has changed significantly in recent years. Clinical guidelines mention traditional and new oral anticoagulants, and the family of antiplatelet agents that can be used in clinical practice has expanded. The possibilities of differentiated antithrombotic therapy depending on the pathogenetic subtype of IS have expanded. The concept of early secondary prevention, new in angioneurology, suggests the possibility of more aggressive management of patients using a combination of antithrombotic drugs. In connection with the increase in life expectancy of patients who have suffered a IS, the issues of choosing drugs with good efficacy and a better safety profile have become relevant. The article discusses the practical aspects of managing patients in the acute period of the disease, during the period of early secondary prevention (90 days), if long-term use of basic treatment strategies is necessary (years).

The Effectiveness of Antiplatelet Therapy and the Factors Influencing It in Patients with Acute Coronary Syndrome before and during the COVID-19 Pandemic

Background and Objectives: Dual antiplatelet therapy (DAPT) is essential in the treatment of patients with acute coronary syndrome (ACS). The objective of this study was to evaluate the effectiveness of antiplatelet medication in our practice and to investigate the factors that influence it. Materials and Methods: A prospective cohort observational study was conducted, in which 193 patients with ACS were enrolled. The patients were stented in the catheterization laboratory between May 2019 and October 2020, before and during the COVID-19 pandemic, and were receiving DAPT. Their platelet functions were tested using a Multiplate Analyzer. In addition to this, clinical data, demographics, laboratory tests, and cardiovascular risk factors were also analyzed. Results: 43.46% of the patients treated with aspirin were found to be resistant to it. This phenomenon was more common in men (48.17% vs. 31.48%, p = 0.036), and it was associated with being under the age of 50 (OR: 2.08; 95% CI: 1.11-3.90) and weighing over 70 kg (OR: 3.00; 95% CI: 1.21-7.40). Most of the patients treated with clopidogrel were in the optimal treatment window, while about half of the patients treated with ticagrelor had an exaggerated pharmacological response. Among the laboratory parameters, leukocytosis and platelet count were found to be determinants of platelet reactivity for both the aspirin and ticagrelor treatments. Conclusions: Many patients treated with antiplatelet agents are outside of the treatment window. The results obtained showed that low doses of gastro-resistant aspirin tablets are ineffective, and their efficacy can be influenced by various clinical and laboratory factors. Patients receiving ticagrelor have significantly reduced platelet reactivity, influenced only by certain laboratory indicators. The pandemic significantly influenced the results of the platelet aggregation tests only in patients treated with clopidogrel.

Characterization of the acetylation of cyclooxygenase-isozymes and targeted lipidomics of eicosanoids in serum and colon cancer cells by the new aspirin formulation IP1867B versus aspirin in vitro

Background: Aspirin(acetylsalicylic acid, ASA) is recommended for the secondary prevention of atherothrombotic events and has shown anticancer effects. The current enteric-coated drug formulation may reduce aspirin bioavailability. Liquid formulations could improve aspirin pharmacokinetics and pharmacodynamics. IP1867B is a liquid-aspirin formulation that combines three ingredients, ASA/triacetin/saccharin. Methods: ASA and IP1867B(L-ASA) were assessed in human serum(obtained by allowing to clot human whole blood at 37 °C for 1h), washed platelets, and colonic adenocarcinoma HCA7 cells on eicosanoid generation and COX-isozyme acetylation at Serine529 and 516 by LC-MS/MS. Results: In serum, ASA and L-ASA acted by selectively affecting COX-1-derived eicosanoids, including thromboxane(TX)B2. L-ASA was more potent in inhibiting serum TXB2, a known biomarker of aspirin antiplatelet effect, than ASA. However, ASA and L-ASA were equipotent to acetylate COX-1 in washed platelets and COX-2 in HCA7 cells. In HCA7 cells, ASA and L-ASA acted by inhibiting prostaglandin(PG)E2(the most abundant prostanoid) and TXB2 biosynthesis. In the presence of a high arachidonic acid concentration(100 μM), 15R-hydroxyeicosatetraenoic acid(HETE) was generated at baseline by cancer cell COX-2 and was only slightly enhanced by supratherapeutic concentrations of ASA(1 mM). In whole blood and HCA7 cells treated with ASA or L-ASA, 15-epi-lipoxin(LX)A4 were undetectable. Conclusion: IP1867B was more potent in affecting serum TXB2 generation than ASA. The relevance of this finding deserves evaluation in vivo in humans. In cancer cells, ASA and IP1867B acted by inhibiting PGE2 and TXB2 generation via the acetylation of COX-2. ASA and IP867B at clinically relevant concentrations did not substantially induce the biosynthesis of 15R-HETE and 15-epi-LXA4.

Efficacy and safety of eight types Salvia miltiorrhiza injections in the treatment of unstable angina pectoris: A network meta-analysis

Background: Salvia miltiorrhiza Bunge. [Lamiaceae, danshen] injection classes (SMIC) is widely used in the treatment of unstable angina (UA). However, it is uncertain which SMIC is more effective in terms of UA efficacy. The purpose of this Network Meta-analysis (NMA) was to compare the treatment effects of various SMIC to determine the best SMIC for the treatment of UA. Methods: The China National Knowledge Infrastructure (CNKI), Wanfang Database, China Science and Technology Journal Database (VIP), Chinese Biomedical Literature Database (CBM), PubMed, Web of Science, and Cochrane Library databases were searched to screen randomized controlled trials (RCTs) of SMIC for UA. The search time frame was all from the establishment of the database to May 2022. RevMan 5.3 and Stata 14.0 software were used for NMA. Results: A total of 148 studies including 14,979 patients, including 7,584 cases in the experimental group and 7,395 cases in the control group were included, and eight SMIC were extracted, namely:Danshen injection, Fufang Danshen injection, Guanxinning injection, Danshenchuanxiongqin injection, Danhong injection, Danshentong IIA Huangsuanna injection, Shenxiong Putaotang injection, and Danshenduofensuanyan injection. The results of NMA showed that, in terms of total effective rate, Shenxiong Putaotang injection and Danshenchuanxiongqin injection have the advantage; In terms of ECG efficiency, Danshentong IIA Huangsuanna injection and Danshen injection have an advantage; Danshenchuanxiongqin injection and Danshenduofensuanyan injection were more effective than other SMIC in improving angina pectoris attacks; Shenxiong Putaotang injection has an advantage in improving hs-CRP; Shenxiong Putaotang injection and Danshentong IIA Huangsuanna injection have advantages in improving TC and TG, respectively. Conclusion: The eight SMIC included in the current study were effective in treating UA, Shenxiong Putaotang injection and Danshentong IIA Huangsuanna injection were both superior in improving all outcome indicators. However, there is still a need for larger samples and high-quality randomized controlled trials for more refined comparisons of various SMIC. Systematic Review Registration: [PROSPERO], identifier [CRD42022350872].

Current and Future Insights for Optimizing Antithrombotic Therapy to Reduce the Burden of Cardiovascular Ischemic Events in Patients with Acute Coronary Syndrome

The pharmacological treatment strategies for acute coronary syndrome (ACS) in recent years are constantly evolving to develop more potent antithrombotic agents, as reflected by the introduction of more novel P2Y₁₂ receptor inhibitors and anticoagulants to reduce the ischemic risk among ACS patients. Despite the substantial improvements in the current antithrombotic regimen, a noticeable number of ACS patients continue to experience ischemic events. Providing effective ischemic risk reduction while balancing bleeding risk remains a clinical challenge. This updated review discusses the currently approved and widely used antithrombotic agents and explores newer antithrombotic treatment strategies under development for the initial phase of ACS.

The impact of enteric coating of aspirin on aspirin responsiveness in patients with suspected or newly diagnosed ischemic stroke: prospective cohort study: results from the (ECASIS) study

Background and purpose

Uncertainty remains regarding the impact of enteric-coated aspirin (EC-ASA) on secondary prevention of ischemic stroke compared to plain aspirin (P-ASA). Hence, this study was designed to investigate the effect of EC formulation on ASA response via evaluating thromboxane B2 (TXB2) levels in patients with suspected or newly diagnosed stroke.

Methods

A prospective cohort study on suspected or newly diagnosed ischemic stroke patients who are aspirin-naive was conducted. Patients were received either EC aspirin or plain aspirin for at least 3 days. The primary outcome was the proportion of aspirin non-responsiveness between two groups (level of residual serum TXB2 associated with elevated thrombotic risk (< 99.0% inhibition or TXB2 > 3.1 ng/ml) within 72 h after three daily aspirin doses, while secondary outcomes were the incidence of early gastrointestinal tract (GIT) bleeding with the various aspirin preparations. (Trial registration: Clinicaltrials.gov NCT04330872 registered on 02 April 2020).

Results

Of 42 patients, ischemic strokes were confirmed in both P-ASA (81%) and EC-ASA (67%) arms. ASA non-responsiveness showed no significant difference between the two formulations (P-ASA vs. EC-ASA; 28.6% vs 23.8%; P = 0.726). Univariate and multivariate logistic regression analysis showed that patients treated with EC-ASA were more likely to have a lower rate of non-responders compared to P-ASA (unadjusted OR 0.78; 95% CI 0.20, 3.11); with the risk highest in type 2 diabetic patients with HBA1c > 6.5% (adjusted OR 6; 95% CI 1.02, 35.27; P = 0.047). No incidence of GIT bleeding observed throughout the study.

Conclusion

A significant proportion of ASA non-responsiveness was recorded regardless of ASA formulation administered. The increased risk of ASA non-responsiveness in diabetic patients needs further exploration by larger prospective studies.

Research on Technology of Medicinal Functional Food

Particle coating is one of the oldest pharmaceutical processes that is still in existence. It is the process of applying a thin polymer-based film to a particle or granule containing the active pharmaceutical ingredient. The widely used methods for particle coating are sugar coating, film coating, and enteric coating and the techniques are pan coating, fluidized bed coating, and compression coating. Sugar coating was the earlier coating method, and it was gradually replaced by film coating because it required skilled manipulation. With the technology developing, enteric coating draws more attention. Pan coating is the most classic coating technique, which is applied to sugar coating, film coating and enteric coating. Fluid bed coating is used for a mixture of multiple materials and medicines and keeps the bioavailability high. Compression coating can avoid the harmful effects of moisture and high temperature, while it requires highly accurate machinery.

Pharmacokinetic and Pharmacodynamic Profile of a Novel Phospholipid Aspirin Formulation

Aspirin is one of the most widely used medicines. Although aspirin is commonly utilized for the treatment of several medical conditions, its broadest uptake is for the prevention of recurrent ischemic events in patients with atherosclerotic disease. Its mechanism of action of inhibiting platelet activation via blockade of thromboxane A2 production is unique and is not covered by any other antiplatelet agents. While plain, uncoated, immediate-release aspirin is used in acute settings to help assure rapid absorption, enteric-coated aspirin formulations dominate current chronic use, particularly in North America, including for secondary prevention of cardiovascular events. The unmet needs with current aspirin formulations include a high risk of gastrointestinal (GI) adverse events with plain aspirin, which enteric-coated formulations are not able to overcome, and subject to erratic absorption leading to reduced drug bioavailability. These observations underscore the need for aspirin formulations with a more favorable safety and efficacy profile. Phospholipid-aspirin complex (PL-ASA) is a novel formulation designed to address these needs. It is associated with reduced local acute GI injury compared with plain aspirin, and predictable absorption resulting in more reliable platelet inhibition compared with enteric-coated tablets. This review explores the rationale and pharmacologic profile of PL-ASA intended to address the unmet needs for aspirin therapy.

Aspirin for Primary Cardiovascular Prevention in Patients with Diabetes: Uncertainties and Opportunities

The use of the antiplatelet agent aspirin (acetylsalicylic acid) was previously routinely recommended for the primary prevention of cardiovascular (CV) events in patients with diabetes, but recent large-scale randomized trials have failed to demonstrate a sizeable net clinical benefit with a once-daily, low-dose (81–100 mg) regimen in this population. Previous pharmacokinetic and pharmacodynamic studies have suggested that the aspirin formulation (enteric-coated) and dosing schedule (once daily) studied in randomized trials for primary prevention of CV events defining contemporary clinical practice may not leverage the full potential of the drug, particularly in patients with diabetes. Indeed, the diabetic platelets bear characteristics that increase their thrombotic potential and alter their pharmacologic response to the drug. Consequently, the appropriateness of studying a uniform aspirin regimen in landmark primary prevention trials needs to be revisited. In this review, we present the evidence showing that diabetes not only increases baseline platelet reactivity, but also alters platelet response to aspirin through different mechanisms including a faster platelet turnover rate. Obesity, which is frequently associated with diabetes, also impacts its pharmacokinetics via an increase in distribution volume. Small-scale pharmacokinetic and pharmacodynamic studies have suggested that the relative aspirin resistance phenotype observed in patients with diabetes may be reversed with a twice-daily dosing schedule, and with nonenteric-coated aspirin formulations. Properly powered randomized controlled trials investigating the efficacy and safety of aspirin dosing schedules and formulations tailored to the population of patients with diabetes are urgently required to optimize patient care.

Bleeding avoidance strategies in percutaneous coronary intervention

For many years, bleeding has been perceived as an unavoidable consequence of strategies aimed at reducing thrombotic complications in patients undergoing percutaneous coronary intervention (PCI). However, the paradigm has now shifted towards bleeding being recognized as a prognostically unfavourable event to the same extent as having a new or recurrent ischaemic or thrombotic complication. As such, in parallel with progress in device and drug development for PCI, there is clinical interest in developing strategies that maximize not only the efficacy but also the safety (for example, by minimizing bleeding) of any antithrombotic treatment or procedural aspect before, during or after PCI. In this Review, we discuss contemporary data and aspects of bleeding avoidance strategies in PCI, including risk stratification, timing of revascularization, pretreatment with antiplatelet agents, selection of vascular access, choice of coronary stents and antithrombotic treatment regimens.

Appraising the contemporary role of aspirin for primary and secondary prevention of atherosclerotic cardiovascular events

INTRODUCTION

Although the role of aspirin for primary prevention of atherosclerotic cardiovascular disease (ASCVD) has been disputed, its use in secondary ASCVD prevention is well established. Recent trials of primary prevention do not suggest a significant net benefit with aspirin, whereas accruing evidence supports adopting aspirin-free strategies in the context of potent P2Y₁₂ inhibition for the secondary prevention of selected patients undergoing percutaneous coronary intervention.

AREAS COVERED

This updated review aims at summarizing and appraising the pharmacological characteristics and the contemporary role of aspirin for the primary and secondary prevention of ASCVD.

EXPERT OPINION

Recent trials and metanalyses in the context of primary prevention highlighted a modest reduction in ischemic events with aspirin use, counterbalanced by a significant increase in bleeding events. However, ongoing studies on cancer prevention could modify the current paradigm of the unfavorable benefit-risk ratio of aspirin in patients with no overt ASCVD. Conversely, aspirin use is crucial for secondary ASCVD prevention, both in chronic and acute coronary syndromes. Nevertheless, after a brief period of dual antiplatelet therapy, patients at high bleeding risk may benefit from discontinuation of aspirin if a P2Y₁₂ inhibitor is used, hence reducing the bleeding risk with no rebound in thrombotic events.

[Résistance à l'aspirine : l'ennemi de mon ami est mon ennemi]

Low dose aspirin is an efficient antiplatelet agent to decrease the risk of occlusive arterial events, however it is not infallible. Aspirin resistance describe its inability to block the formation of thromboxane A2 in platelets and/or to produce an inhibitory effect on platelet aggregation. Detection of aspirin resistance relies on the results of various platelet function tests or on blood and urinary thromboxane metabolites concentrations, but these methods show very low correlation and reproducibility. Moreover, light-transmission aggregometry using arachidonic acid, known as the reference functional assay, requires technical expertise. The incidence rate of aspirin resistance amoung populations suffering from cardiovascular diseases is about 25%, however there is a wide variability depending on the specificity of the used test and the clinical features of the considered population. Aspirin resistance is associated with the recurrence of arterial occlusive events: the odds ratio is about 4 all tests combined, therefore it could be considered as a risk marker. Evidence is lacking regarding the relevance of these tests to resort an intensification of the antithrombotic treatment, and experts recommend to reserve their use for high-risk situations. Nevertheless several studies have explored the effect of dose increases or intake frequency increases, and revealed encouraging results regarding pharmacodynamic endpoints. The reasons for aspirin resistance are numerous, often remain debate, and can accumulate to result in poor response to aspirin.

Contemporary Clinical Use of Aspirin: Mechanisms of Action, Current Concepts, Unresolved Questions, and Future Perspectives

The ability of aspirin to inhibit platelet aggregation has positioned this agent within the most frequently used drugs worldwide. The aim of this article is to review the contemporary clinical use of aspirin and also to discuss unresolved issues not yet translated into clinical practice. Results from several clinical trials have led to strong guideline recommendations for aspirin use in the acute management and secondary prevention of cardiovascular disease. On the contrary, guidelines regarding aspirin use as primary prevention of cardiovascular disease are almost conservative, supported by recent trials reporting that the bleeding risk outweighs the potential benefits in most patients. In pregnancy, aspirin has proved efficient in preventing preeclampsia and small-for-gestational-age births in women at high risk, and is hence widely recommended in clinical guidelines. Despite the vast amount of clinical data on aspirin, several unresolved questions remain. Randomized trials have reported that aspirin reduces the risk of recurrent venous thromboembolism, but the clinical relevance remains limited, because direct oral anticoagulants are more effective. Laboratory studies suggest that a twice-daily dosing regimen or evening intake may lead to more efficient platelet inhibition, and the potential clinical benefit of such strategies is currently being explored in ongoing clinical trials. Enteric-coated formulations of aspirin are frequently used, but it remains unclear if they are safer and as efficient as plain aspirin. In the future, aspirin use after percutaneous coronary interventions might not be mandatory in patients who also need anticoagulant therapy, as several trials support shorter aspirin duration strategies. On the other hand, new treatment indications for aspirin will likely arise, as there is growing evidence that aspirin may reduce the risk of colorectal cancer and other types of cancer.

Stroke Prevention: Little-Known and Neglected Aspects

Combining available therapies has the potential to reduce the risk of stroke by 80% or more. A comprehensive review of all aspects of stroke prevention would be very lengthy; in this narrative review, we focus on some aspects of stroke prevention that are little-known and/or neglected. These include the following: (1) implementation of a Mediterranean diet; (2) B vitamins to lower homocysteine; (3) coordinated approaches to smoking cessation; (4) intensive lipid-lowering therapy; (5) lipid lowering in the elderly; (6) physiologically individualized therapy for hypertension based on renin/aldosterone phenotyping; (7) avoiding excessive blood pressure reduction in patients with stiff arteries; (8) treatment of insulin resistance with pioglitazone in stroke patients with prediabetes and diabetes; (9) impaired activation of clopidogrel in patients with variants of CYP2C19; (10) aspirin pseudoresistance due to enteric coating; (11) rationale for anticoagulation in patients with embolic stroke of unknown source; (12) pharmacologic properties of direct-acting oral anticoagulants that should be considered when choosing among them; (13) the identification of which patients with asymptomatic carotid stenosis are at a high enough risk to benefit from carotid endarterectomy or stenting; and (14) the importance of age in choosing between endarterectomy and stenting. Stroke prevention could be improved by better recognition of these issues and by implementation of the principles derived from them.

In-vitro and in-vivo metabolism of different aspirin formulations studied by a validated liquid chromatography tandem mass spectrometry method

Low-dose aspirin (ASA) is used to prevent cardiovascular events. The most commonly used formulation is enteric-coated ASA (EC-ASA) that may be absorbed more slowly and less efficiently in some patients. To uncover these "non-responders" patients, the availability of proper analytical methods is pivotal in order to study the pharmacodynamics, the pharmacokinetics and the metabolic fate of ASA. We validated a high-throughput, isocratic reversed-phase, negative MRM, LC-MS/MS method useful for measuring circulating ASA and salicylic acid (SA) in blood and plasma. ASA-d4 and SA-d4 were used as internal standards. The method was applied to evaluate: (a) the "in vitro" ASA degradation by esterases in whole blood and plasma, as a function of time and concentration; (b) the "in vivo" kinetics of ASA and SA after 7 days of oral administration of EC-ASA or plain-ASA (100 mg) in healthy volunteers (three men and three women, 37-63 years). Parameters of esterases activity were Vmax 6.5 ± 1.9 and Km 147.5 ± 64.4 in plasma, and Vmax 108.1 ± 20.8 and Km 803.2 ± 170.7 in whole blood. After oral administration of the two formulations, tmax varied between 3 and 6 h for EC-ASA and between 0.5 and 1.0 h for plain-ASA. Higher between-subjects variability was seen after EC-ASA, and one subject had a delayed absorption over eight hours. Plasma AUC was 725.5 (89.8-1222) for EC-ASA, and 823.1(624-1196) ng h/mL (median, 25-75% CI) for plain ASA. After the weekly treatment, serum levels of TxB2 were very low (< 10 ng/mL at 24 h from the drug intake) in all the studied subjects, regardless of the formulation or the tmax. This method proved to be suitable for studies on aspirin responsiveness.

Clopidogrel underactivity is a common in patients with acute symptomatic severe carotid stenosis

BACKGROUND

Clopidogrel is commonly used for secondary stroke prevention in patients with large vessel stenosis. Reduced Clopidogrel high on treatment platelet reactivity (CR) can lead to Clopidogrel underactivity (CU) causing acute thrombosis. However, the prevalence of CU among patients with acute symptomatic carotid disease remains unknown. Therefore, we aimed to find the prevalence and identify the predictors for CU among patients with acutely symptomatic carotid stenosis.

PATIENTS AND METHODS

Over the span of 14 months, CR was measured at the time of endovascular procedure in all patients undergoing angiography and stenting because of acute symptomatic carotid stenosis. Only patients treated per institutional protocol with a combination of Clopidogrel and Aspirin were included. CR was measured with VerifyNowP2Y12 reaction units (PRU) and CU was defined as PRU > 208. Patients with CU were compared to those without CU.

RESULTS

Thirty-five patients were included (mean age 71.3 ± 10, 76% men) and twelve (34.3%, mean age 71.8 ± 8.4, 58% men) had CU at the time of endovascular intervention. On univariate analysis more severe carotid stenosis was seen in CU patients (92.6 ± 6.5% vs 81.6 ± 13.6%, p = 0.013) and percent stenosis was independently associated with CU on multivariate analysis (p = 0.023).

CONCLUSIONS

CU is present in 1 of every 3 patients with acutely symptomatic carotid disease. The current results suggest that CR testing should become part of routine care in patients with acutely symptomatic carotid disease.

Overview of Aspirin and Platelet Biology

Aspirin (ASA) has historically been one of the most important drugs in cardiology and has long been the cornerstone of antiplatelet therapy. Although its role in acute coronary syndrome remains undisputed, emerging data suggest that reappraisal of the efficacy of long-term ASA in some primary and secondary prevention may be warranted. The aim of this review is to place these new results in the context of previous evidence on aspirin by appraising the current body of evidence on its use of for cardiovascular diseases. This overview first summarizes the history of the discovery of aspirin, as well as its pharmacology and the concept of ASA resistance. We subsequently recapitulate the evidence of ASA on primary prevention and secondary prevention starting from the classical studies in order to serve as an introductory background to the examination of the most recent clinical trials that will be performed in the rest of the articles of this Supplement. Although the benefit of ASA in acute coronary syndrome remains incontrovertible, emerging evidence challenge the universal need for primary prevention, or for lifelong treatment in secondary prevention or all adults with stable coronary disease who are at highest risk for ASA-induced bleeding. The role of aspirin is quickly changing in recent times and this review provides a review for the clinician about the current role of this drug in cardiovascular care.

Aspirin Resistance as a Result of Impaired Interaction of Platelets and Neutrophils in Patients with Coronary Heart Disease

Aim. To study the relationship between the levels of synthesis of reactive oxygen species (ROS) by platelets and neutrophils in patients with coronary heart disease (CHD) before and after coronary artery bypass grafting (CABG), depending on sensitivity to acetylsalicylic acid (ASA).

Material and methods. The study included 95 patients with coronary artery disease who are indicated for CABG surgery. The control group consisted of 30 healthy donors. The antiplatelet therapy was stopped for at least 5 days before CABG. In the postoperative period, from the first day, all patients were received 100 mg of an enteric form of acetylsalicylic acid (ASA). Resistance to ASA was determined at the level of platelet aggregation with arachidonic acid ≥20% by optical agregometry at least at one observation point: before CABG, on 1-3 day and on 8-10 day after surgery. We evaluated the spontaneous and induced lucigenin-dependent chemiluminescence (CL) of platelets (ADP induction) and neutrophils (zymosan induction) by the exit time to maximum intensity (Tmax), maximum intensity (Imax) and area (S) under the CL curve.

Results. 70.5% sensitive (sASA) and 29.5% resistant (rASA) to ASA patients were revealed. Prior to CABG, in sASA patients, the Imax of spontaneous and zymosan-induced neutrophil CL and CL platelet activity was increased relative to control values. Tmax of spontaneous platelet CL, Imax and S under the ADP-induced platelet CL curve were lower in sASA patients, if to compare with rASA patients. On the 1st and 8-10th day after CABG in sASA patients, the CL indicators of neutrophil and platelet activity also remained elevated compared to control values. On the 1st day after CABG decreased levels of S under the spontaneous CL curve of neutrophils in rASA patients was established compared with sASA patients, and increased levels of Imax and S under the curve of induced neutrophil CL were detected in comparison with the control range. In rASA patients, the values of Tmax of spontaneous platelet CL decreased in relation to the values detected in the control group and sASA patients. On the 8–10th day after CABG, most indicators of spontaneous and zymosan-induced CL neutrophils in rASA patients were also increased compared to control values. In rASA patients a positive correlation of Imax-induced CL was found (r=0.83) on the 1st day after CABG and negative correlations of Tmax of spontaneous CL (r=- 0.75) and S under the curve induced CL (r=-0.70) on the 8-10th day were detected between platelets and neutrophils.

Conclusion. In sASA patients with coronary heart disease before and after CABG, a high level of synthesis of superoxide radical by neutrophils and platelets was detected. The relationship between the levels of the synthesis of superoxide radical by neutrophils and platelets was found only after CABG in rASA patients. Increased synthesis of superoxide radical due to metabolic and regulatory relationships in neutrophils and platelets stimulates pro-inflammatory processes in coronary artery disease and determines the sensitivity of platelets to ASA.

Aspirin in Primary Prevention: What Changed? A Critical Appraisal of Current Evidence

Aspirin has been the mainstay of both secondary and primary prevention of cardiovascular disease for half a century. In 2018, 3 trials showed a modest reduction in cardiovascular outcomes that appeared counterbalanced by the risk of clinically significant bleeding. The latest ACC/AHA primary prevention guidelines downgraded their recommendation for aspirin use in primary prevention to that of physician preference. Despite the consistent and robust evidence previously supporting the use of aspirin in cardiovascular disease prevention, little discussion has been given to mechanisms or analytic explanations for this revision of recommendations. In this review, we explore 3 possible mechanisms that may have contributed to the alteration of our perception of aspirin's role in primary prevention. These include changes in the population potentially using aspirin in primary prevention, changes in cardiovascular disease and its presentation, and changes in aspirin itself. Here we present a translational look at knowledge gaps that should be addressed to better guide contemporary aspirin use in primary prevention. In conclusion, based on these considerations, the current recommendations might be improved by recalibration of the cardiovascular risk threshold above which aspirin should be recommended for primary prevention, including the incorporation of newer risk assessment modalities such as calcium scoring. A second enhancement would be developing a bleeding risk calculator to support clinicians' assessment of risk vs benefit. The use of enteric-coated aspirin vs noncoated aspirin should also be reassessed.

Antithrombotic Therapy for Atherosclerotic Cardiovascular Disease Risk Mitigation in Patients With Coronary Artery Disease and Diabetes Mellitus

Patients with diabetes mellitus (DM) are characterized by enhanced thrombotic risk attributed to multiple mechanisms including hyperreactive platelets, hypercoagulable status, and endothelial dysfunction. As such, they are more prone to atherosclerotic cardiovascular events than patients without DM, both before and after coronary artery disease (CAD) is established. In patients with DM without established CAD, primary prevention with aspirin is not routinely advocated because of its increased risk of major bleeding that largely offsets its ischemic benefit. In patients with DM with established CAD, secondary prevention with antiplatelet drugs is an asset of pharmacological strategies aimed at reducing the risk of atherosclerotic cardiovascular events and their adverse prognostic consequences. Such antithrombotic strategies include single antiplatelet therapy (eg, with aspirin or a P2Y₁₂ inhibitor), dual antiplatelet therapy (eg, aspirin combined with a P2Y₁₂ inhibitor), and dual-pathway inhibition (eg, aspirin combined with the vascular dose of the direct oral anticoagulant rivaroxaban) for patients with chronic ischemic heart disease, acute coronary syndromes, and those undergoing percutaneous coronary intervention. Because of their increased risk of thrombotic complications, patients with DM commonly achieve enhanced absolute benefit from more potent antithrombotic approaches compared with those without DM, which most often occurs at the expense of increased bleeding. Nevertheless, studies have shown that when excluding individuals at high risk for bleeding, the net clinical benefit favors the use of intensified long-term antithrombotic therapy in patients with DM and CAD. Several studies are ongoing to establish the role of novel antithrombotic strategies and drug formulations in maximizing the net benefit of antithrombotic therapy for patients with DM. The scope of this review article is to provide an overview of current and evolving antithrombotic strategies for primary and secondary prevention of atherosclerotic cardiovascular events in patients with CAD and DM.

Management of asymptomatic carotid stenosis

Patients with asymptomatic carotid stenosis (ACS) are at very high risk of coronary events, so they should all receive intensive medical therapy. What is often accepted as “best medical therapy” is usually suboptimal. Truly intensive medical therapy includes lifestyle modification, particularly smoking cessation and a Mediterranean diet. All patients with ACS should receive intensive lipid-lowering therapy, should have their blood pressure well controlled, and should receive B vitamins for lowering of plasma total homocysteine (tHcy) if levels are high; a commonly missed cause of elevated tHcy is metabolic B12 deficiency, which should be diagnosed and treated. Most patients with ACS would be better treated with intensive medical therapy than with either carotid endarterectomy (CEA) or stenting (CAS). A process called “treating arteries instead of treating risk factors” markedly reduced the risk of ACS in an observational study; a randomized trial vs. usual care should be carried out. The few patients with ACS who could benefit (~15%, or perhaps more if recent evidence regarding the risk of intraplaque hemorrhage is borne out) can be identified by a number of features. These include microemboli on transcranial Doppler, intraplaque hemorrhage, reduced cerebrovascular reserve, and echolucency of plaques, particularly “juxtaluminal black plaque”. No patient should be subjected to CAS or CEA without evidence of high-risk features, because in most cases the 1-year risk of stroke or death with intervention is higher with either CEA (~2%) or CAS (~4%) than with intensive medical therapy (~0.5%). Most patients, particularly the elderly, would be better treated with CEA than CAS. Most strokes can be prevented in patients with ACS, but truly intensive medical therapy is required.

Stroke Prevention in Older Adults: Recent Advances

The risks of stroke and dementia increase steeply with age, and both are preventable. At present, the best way to preserve cognitive function is to prevent stroke. Therapeutic nihilism based on age is common and unwarranted. We address recent advances in stroke prevention that could contribute greatly to prevention of stroke and dementia at a time when the aging of the population threatens to markedly increase the incidence of both. Issues discussed: (1) old patients benefit even more from lipid-lowering therapy than do younger patients; (2) patients with stiff arteries are at risk from a target systolic blood pressure <120 mm Hg; (3) the interaction of the intestinal microbiome, age, and renal function has important dietary implications for older adults; (4) anticoagulation with direct-acting oral anticoagulants should be prescribed more to old patients with atrial fibrillation; (5) B vitamins to lower homocysteine prevent stroke; and (6) most old patients in whom intervention is warranted for carotid stenosis would benefit more from endarterectomy than from stenting. An 80-year-old person has much to lose from a stroke and should not have effective therapy withheld on account of age. Lipid-lowering therapy, a more plant-based diet, appropriate anticoagulation or antiplatelet therapy, appropriate blood pressure control, B vitamins to lower homocysteine, and judicious intervention for carotid stenosis could do much to reduce the growing burden of stroke and dementia.

Recent advances in preventing recurrent stroke

Since a 2017 update, there have been important advances in stroke prevention. These include new evidence about nutrition, antiplatelet therapy, anticoagulation, lipid-lowering therapy, hypertension control, pioglitazone, and carotid endarterectomy and stenting. Evidence regarding toxic metabolites produced by the intestinal microbiome from egg yolk and red meat has important dietary implications, particularly for patients with impaired renal function, including the elderly. They should avoid egg yolk and red meat and limit the intake of animal flesh. Higher doses of folic acid may be needed for patients with the T allele of MTHFR, so it may not be sufficient to give vitamin B12 (methylcobalamin) alone, even in countries with folate fortification. There is now good evidence that lipid-lowering therapy is even more beneficial in the elderly than in younger patients; we should be using lipid-lowering therapy more intensively, often/usually combining statins with ezetimibe. There is new evidence that lower systolic blood pressure targets are better for most patients, but a subgroup with stiff arteries, a wide pulse pressure, and a diastolic pressure of <60 would be more likely to be harmed than helped by aiming for a systolic target of <120 mmHg. There is a better understanding of how the pharmacological properties of direct-acting oral anticoagulants and the metabolism of antiplatelet agents should inform decisions about the use of these agents. Pioglitazone markedly reduces the risk of stroke, both in diabetics and prediabetics; it should be used more widely. It is now clear that carotid endarterectomy is safer than stenting and that the difference is strongly affected by age. Most patients, and in particular older patients, would be better served by endarterectomy than stenting.

Cardiovascular Biology of Prostanoids and Drug Discovery

Prostanoids are a group of bioactive lipids that are synthesized de novo from membrane phospholipid-released arachidonic acid and have diverse functions in normal physiology and disease. NSAIDs (non-steroidal anti-inflammatory drugs), which are among the most commonly used medications, ameliorate pain, fever, and inflammation by inhibiting COX (cyclooxygenase), which is the rate-limiting enzyme in the biosynthetic cascade of prostanoids. The use of NSAIDs selective for COX-2 inhibition increases the risk of a thrombotic event (eg, myocardial infarction and stroke). All NSAIDs are associated with an increased risk of heart failure. Substantial variation in clinical responses to aspirin exists and is associated with cardiovascular risk. Limited clinical studies suggest the involvement of prostanoids in vascular restenosis in patients who received angioplasty intervention. mPGES (microsomal PG [prostaglandin] E synthase)-1, an alternative target downstream of COX, has the potential to be therapeutically targeted for inflammatory disease, with diminished thrombotic risk relative to selective COX-2 inhibitors. mPGES-1-derived PGE₂ critically regulates microcirculation via its receptor EP (receptor for prostanoid E) 4. This review summarizes the actions and associated mechanisms for modulating the biosynthesis of prostanoids in thrombosis, vascular remodeling, and ischemic heart disease as well as their therapeutic relevance.

Pharmacokinetic/pharmacodynamic assessment of a novel, pharmaceutical lipid-aspirin complex: results of a randomized, crossover, bioequivalence study

Aspirin (acetylsalicylic acid, ASA) can lead to gastrointestinal mucosal injury through disruption of its protective phospholipid bilayer. A liquid formulation of a novel pharmaceutical lipid-aspirin complex (PL-ASA) was designed to prevent this disruption. We sought to determine the pharmacokinetic (PK)/pharmacodynamic (PD) characteristics of PL-ASA compared with immediate release aspirin (IR-ASA). In this active-control crossover study, 32 healthy volunteers were randomized to receive 1 of 2 dose levels (a single dose of 325 mg or 650 mg) of either PL-ASA or IR-ASA. After a 2-week washout period between treatment assignments, subjects received a single dose of the alternative treatment, at the same dose level. The primary objectives of the study were to assess, for PL-ASA and IR-ASA at 325 mg and 650 mg dose levels, PK and PD bioequivalence, and safety, over a 24-h period after administration of both drugs. PK parameters were similar for PL-ASA and IR-ASA, and met FDA-criteria for bioequivalence. Regarding PD, both drugs also showed C_min TxB2 values below 3.1 ng/mL (cut-off associated with decreased cardiovascular events) and > 99% inhibition of serum TxB2 ( ≥ 95% inhibition represents the cut-off for aspirin responders) along with similar results in several secondary PK/PD parameters. There were no serious adverse events or changes from baseline in vital signs or laboratory values in either of the 2 treatment groups. PL-ASA's novel liquid formulation has similar PK and PD performance compared with IR-ASA, supporting functional and clinical equivalence. These data coupled with the improved gastric safety of PL-ASA suggest that this novel formulation may exhibit an improved benefit-risk profile, warranting evaluation in future trials.Clinical trial registration: http://www.clinicaltrials.gov . Unique Identifier: NCT04008979.

Choosing the right therapy for a patient with asymptomatic carotid stenosis

Introduction: Most patients with asymptomatic carotid stenosis (ACS) now have a lower risk with intensive medical therapy than with stenting (CAS) or endarterectomy (CEA); the annual risk of stroke or death with intensive medical therapy is ~ 0.5%, vs. a periprocedural risk with CAS of ~ 2.5-4.1% with CAS, and ~ 1.4-1.8% with CEA. The excess risk of CAS is greater in older patients.Areas covered: Discussed are the need for intensive medical therapy, the nature of intensive medical therapy, approaches to identifying the few patients with ACS who could benefit from CEA or CAS, and which patients would be better suited to CEA vs. CAS.Expert opinion: All patients with ACS are at high risk of cardiovascular events, soshould receive intensive medical therapy including lifestyle modification, intensive lipid-lowering, B vitamins to lower homocysteine (using methylcobalamin rather than cyanocobalamin), and appropriate antithrombotic therapy. High-risk patients who could benefit from intervention can be identified by clinical and imaging features including transcranial Doppler embolus detection, ulceration, intraplaque hemorrhage, reduced cerebrovascular reserve, plaque echolucency, silent infarction on brain imaging, and progression of stenosis. Most patients whose risk of stroke warrants intervention would be better treated with CEA than with CAS.

Platelet Function Test Use for Patients with Coronary Artery Disease in the Early 2020s

In the field of antithrombotics, precision medicine is of particular interest, as it may lower the incidence of potentially life-threatening side effects. Indeed, antiplatelet drugs such as P2Y₁₂ inhibitors are one of the most common causes of emergency admissions for drug-related adverse events. The last ten years have seen a continuous debate on whether platelet function tests (PFTs) should be used to tailor antiplatelet drugs to cardiovascular patients. Large-scale randomized studies investigating the escalation of antiplatelet therapies according to the results of PFTs were mostly negative. Potent P2Y₁₂ inhibitors are recommended as a first-line treatment in acute coronary syndrome patients, bringing the bleeding risk at the forefront. De-escalation from prasugrel or ticagrelor to clopidogrel is now considered, with or without the use of a PFT. This review covers recent advances in escalation and de-escalation strategies based on PFTs in various clinical settings. It also describes the main features of the most popular platelet function tests as well as the potential added value of genetic testing. Finally, we detail practical suggestions on how PFTs could be used in clinical practice.

Relationship between 'on-treatment platelet reactivity', shear stress, and micro-embolic signals in asymptomatic and symptomatic carotid stenosis

BACKGROUND

Assessment of 'high on-treatment platelet reactivity (HTPR)' could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy.

METHODS

This prospective, multi-centre study assessed antiplatelet-HTPR status and its relationship with micro-emboli signals (MES) in asymptomatic vs. symptomatic ≥ 50-99% carotid stenosis. Platelet function/reactivity was assessed under 'moderately high shear stress' with the PFA-100^® and 'low shear stress' with VerifyNow^® and Multiplate^® analysers. Bilateral 1-h transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES + ve or MES - ve.

RESULTS

Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 patients in the 'late phase' (≥ 3 months) after TIA/ischaemic stroke. Median daily aspirin doses were higher in early symptomatic (225 mg; P < 0.001), but not late symptomatic (75 mg; P = 0.62) vs. asymptomatic patients (75 mg). There was a lower prevalence of aspirin-HTPR in early (28.6%; P = 0.028), but not late symptomatic (38.9%; P = 0.22) compared with asymptomatic patients (56.7%) on the PFA-100^®, but not on the VerifyNow^® or Multiplate^® (P ≤ 0.53). Early symptomatic patients had a higher prevalence of aspirin-HTPR on the PFA-100^® (28.6%) vs. VerifyNow^® (9.5%; P = 0.049), but not Multiplate^® assays (11.9%, P = 0.10). There was no difference in aspirin-HTPR prevalence between any symptomatic vs. asymptomatic MES + ve or MES - ve subgroup.

DISCUSSION

Recently symptomatic moderate-severe carotid stenosis patients had a lower prevalence of aspirin-HTPR than their asymptomatic counterparts on the PFA-100^®, likely related to higher aspirin doses. The prevalence of antiplatelet-HTPR was positively influenced by higher shear stress levels, but not MES status.

Simulated, biorelevant, clinically relevant or physiologically relevant dissolution media: The hidden role of bicarbonate buffer

In-vitro dissolution testing of pharmaceutical formulations has been used as a quality control test for many years. At early drug product development, in vivo predictive dissolution testing can be used for guidance in the rational selection of candidate formulations that best fit the desired in vivo dissolution characteristics. At present, the most widely applied dissolution media are phosphate-based buffers and, in some cases, the result of dissolution tests performed in such media have demonstrated reasonable/acceptable IVIVCs. However, the presence of phosphates in human GI luminal fluids is insignificant, which makes the use of such media poorly representative of the in vivo environment. The gastrointestinal lumen has long been shown to be buffered by bicarbonate. Hence, much interest in the development of suitable biorelevant in vitro dissolution media based on bicarbonate buffer systems has evolved. However, there are inherent difficulties associated with these buffers, such as maintaining the pH throughout the dissolution test, as CO₂ tends to leave the system. Various mathematical models have been proposed to analyze bicarbonate buffers and they are discussed in this review. Approaches such as using simpler buffer systems instead of bicarbonate have been proposed as surrogate buffers to produce an equivalent buffer effect on drug dissolution on a case-by-case basis. There are many drawbacks related to simpler buffers systems including their poor in vivo predictability. Considerable discrepancies between phosphate and bicarbonate buffer dissolution results have been reported for certain dosage forms, e.g. enteric coated formulations. The role and need of bicarbonate-based buffers in quality control testing requires scientific analysis. This review also encompasses on the use of bicarbonate-based buffers as a potentially in vivo predictive dissolution medium for enteric coated dosage forms.

Mechanistic analysis and experimental verification of bicarbonate-controlled enteric coat dissolution: Potential in vivo implications

Enteric coatings have shown in vivo dissolution rates that are poorly predicted by traditional in vitro tests, with the in vivo dissolution being considerably slower than in vitro. To provide a more mechanistic understanding of this, the dependence of the release properties of various enteric-coated (EC) products on bulk pH and bicarbonate molarity was investigated. It was found that, at presumably in vivo-relevant values, the bicarbonate molarity is a more significant determinant of the dissolution profile than the bulk pH. The findings also indicate that this steep relationship between the dissolution of enteric coatings and bicarbonate molarity limits those coatings' performance in vivo. This is attributed to the relatively low bicarbonate molarities in human intestinal fluids. Further, the hydration and dehydrations kinetics of carbonic acid and carbon dioxide are not sufficiently rapid to reach equilibrium in the diffusion layer surrounding a dissolving ionizable solid. This results in the effective pKa of bicarbonate in the diffusion layer being lower than that determined potentiometrically at equilibrium in the bulk surrounding fluid. These results demonstrate the importance of thoroughly investigating the intestinal bicarbonate concentrations and using bicarbonate buffers or properly designed surrogates (if possible) when evaluating enteric drug products during product development and quality control.