Prasugrel in critically ill patients

Cangrelor - Expanding therapeutic options in patients with acute coronary syndrome

Cangrelor is the only intravenous P2Y12 receptor antagonist. It is an adenosine triphosphate analog that selectively, directly, and reversibly binds to the platelet P2Y12 receptors exerting its antiaggregatory effect. Cangrelor is characterized by linear, dose-dependent pharmacokinetics and rapid onset of action providing potent platelet inhibition exceeding 90%. Cangrelor is rapidly metabolized by endothelial endonucleotidase; thus, its half-life is 2.9 to 5.5 min, and its antiplatelet effect subsides within 60 to 90 min. Data originating from three pivotal cangrelor trials (CHAMPION PLATFORM, CHAMPION PCI, and CHAMPION PHOENIX) indicate that cangrelor reduces the risk of periprocedural thrombotic complications during percutaneous coronary intervention at the expense of mild bleedings. Its unique pharmacological properties allow it to overcome the limitations of oral P2Y12 receptor inhibitors, mainly related to the delayed and decreased bioavailability and antiplatelet effect of these agents, which are often observed in the setting of acute coronary syndrome. Subgroups of patients who could theoretically benefit the most from cangrelor include those in whom pharmacokinetics and pharmacodynamics of oral P2Y12 receptor antagonists are most disturbed, namely patients with ST-segment elevation myocardial infarction, those treated with opioids, with mild therapeutic hypothermia, or in cardiogenic shock. Cangrelor could also be useful if bridging is required in patients undergoing surgery. According to the current guidelines cangrelor may be considered in P2Y12 receptor inhibitor-naïve patients undergoing percutaneous coronary intervention in both acute and stable settings.

Evaluating the pharmacokinetic and pharmacodynamic impact of different modes of ticagrelor administration

INTRODUCTION

Alternative administration modes for oral P2Y12 inhibitors, particularly ticagrelor, have emerged as a potential alternative to overcome the limitations associated with the delayed onset of action of these drugs in patients who are unable to swallow or with impaired absorption.

AREAS COVERED

This comprehensive literature review aims to provide an overview of the current state of knowledge on the pharmacokinetics and administration modes of ticagrelor, including factors that may affect its action. It also compares the pharmacokinetics of ticagrelor with that of other drugs with similar uses to provide a comprehensive understanding of the potential advantages and limitations of different modalities of P2Y12 administration. For this purpose, Embase, Medline, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, Google Scholar, and ClinicalTrials.gov were searched from database inception to July 2023.

EXPERT OPINION

Among the different alternatives, crushed formulations, especially for ticagrelor, have emerged as the most promising option, showing early and robust platelet inhibition. However, important questions remain unanswered, such as the comparative clinical benefits of crushed ticagrelor versus standard administration, the cost-effectiveness of alternative modes compared to intravenous P2Y12 inhibitors such as cangrelor, and the important limitations associated with the concomitant use of opioids, who have been proven to impair even the action of crushed ticagrelor.

Negative Impact of ST-Segment Elevation Myocardial Infarction and Morphine Dose on Ticagrelor Uptake and Pharmacodynamics: A Population PK/PD Analysis of Pooled Individual Participant Data

BACKGROUND

Ticagrelor is widely used in patients with stable and acute coronary artery disease. Understanding the factors that influence its pharmacokinetics (PK) and pharmacodynamics (PD) could improve therapeutic outcomes. We therefore performed a pooled population PK/PD analysis using individual patient data from two studies. We focused on the impact of morphine administration and ST-segment elevation myocardial infarction (STEMI) on the risk of high platelet reactivity (HPR) and dyspnea.

METHODS

A parent-metabolite population PK/PD model was developed based on data from 63 STEMI, 50 non-STEMI, and 25 chronic coronary syndrome (CCS) patients. Simulations were then run to evaluate the risk of non-response and adverse events associated with the identified variability factors.

RESULTS

The final PK model consisted of first-order absorption with transit compartments, distribution with two compartments for ticagrelor and one compartment for AR-C124910XX (active metabolite of ticagrelor), and linear elimination for both drugs. The final PK/PD model was an indirect turnover model with production inhibition. Morphine dose and STEMI, independently, had a significant negative effect on the absorption rate (reduction of log([Formula: see text]) by 0.21×morphine dose (mg) and by 2.37 in STEMI patients, both p < 0.001), and the presence of STEMI significantly impacted both efficacy and potency (both p < 0.001). The simulations run with the validated model showed a high rate of non-response in patients with those covariates (RR 1.19 for morphine, 4.11 for STEMI and 5.73 for morphine and STEMI, all three p < 0.001). By increasing ticagrelor dosage, the negative morphine effect was reversible in patients without STEMI and just limited in patients with STEMI.

CONCLUSION

The developed population PK/PD model confirmed the negative impact of morphine administration and presence of STEMI on ticagrelor PK and antiplatelet effect. Increasing ticagrelor doses seems effective in morphine users without STEMI, whereas the STEMI effect is not entirely reversible.

Pretreatment with P2Y12 Receptor Inhibitors in Acute Coronary Syndromes-Is the Current Standpoint of ESC Experts Sufficiently Supported?

Excessive platelet reactivity plays a pivotal role in the pathogenesis of acute myocardial infarction. Today, the vast majority of patients presenting with acute coronary syndromes qualify for invasive treatment strategy and thus require fast and efficient platelet inhibition. Since 2008, in cases of ST-elevation myocardial infarction, the European Society of Cardiology guidelines have recommended pretreatment with a P2Y₁₂ inhibitor. This approach has become the standard of care in the majority of centers worldwide. Nevertheless, the latest guidelines for the management of patients presenting with acute coronary syndrome without persisting ST-elevation preclude routine pretreatment with the P2Y₁₂ receptor inhibitor. Those who oppose pretreatment support their stance with trials failing to prove the benefits of this strategy at the cost of an increased risk of major bleeding, especially in individuals inappropriately diagnosed with an acute coronary syndrome, thus having no indication for platelet inhibition. However, adequate platelet inhibition requires even up to several hours after application of a loading dose of P2Y₁₂ receptor inhibitors. Omission of data from pharmacokinetic and pharmacodynamic studies in the absence of data from clinical studies makes generalization of the pretreatment recommendations difficult to accept. We aimed to review the scientific evidence supporting the current recommendations regarding pretreatment with P2Y₁₂ inhibitors.

Clinical pharmacology of antiplatelet drugs

INTRODUCTION

Platelets play a key role in arterial thrombosis and antiplatelet therapy is pivotal in the treatment of cardiovascular disease. Current antiplatelet drugs target different pathways of platelet activation and show specific pharmacodynamic and pharmacokinetic characteristics, implicating clinically relevant drug-drug interactions.

AREAS COVERED

This article reviews the role of platelets in hemostasis and cardiovascular thrombosis, and discusses the key pharmacodynamics, drug-drug interactions and reversal strategies of clinically used antiplatelet drugs.

EXPERT OPINION

Antiplatelet therapies target distinct pathways of platelet activation: thromboxane A₂ synthesis, adenosine diphosphate-mediated signaling, integrin α_IIbβ₃ (GPIIb/IIIa), thrombin-mediated platelet activation via the PAR1 receptor and phosphodiesterases. Key clinical drug-drug interactions of antiplatelet agents involve acetylsalicylic acid - ibuprofen, clopidogrel - omeprazole, and morphine - oral P2Y₁₂ inhibitors, all of which lead to an attenuated antiplatelet effect. Platelet function and genetic testing and the use of scores (ARC-HBR, PRECISE-DAPT, ESC ischemic risk definition) may contribute to a more tailored antiplatelet therapy. High on-treatment platelet reactivity presents a key problem in the acute management of ST-elevation myocardial infarction (STEMI). A treatment strategy involving early initiation of an intravenous antiplatelet agent may be able to bridge the gap of insufficient platelet inhibition in high ischemic risk patients with STEMI.

The use of point-of-care testing in detecting platelet function recovery in a patient treated with prasugrel undergoing urgent surgical revascularization

A recent administration of potent P2Y₁₂ receptor inhibitor such as prasugrel in patients undergoing cardiac surgery remains a dilemma and little is known about its impact on platelet function recovery. Guidelines recommend discontinuation of prasugrel 7 days before surgery to reduce the risk of surgery-related bleeding. Patients at risk may benefit from preoperative platelet function testing to guide individualized preoperative waiting time. We present a rare case of complete function recovery in a patient treated with prasugrel revealed by preoperative platelet function monitoring before urgent coronary artery bypass surgery (CABG). A complete platelet function recovery was revealed by platelet function testing after discontinuation of prasugrel for four days and patient underwent urgent CABG without increased risk of postoperative bleeding. Our case with a review of literature emphasized that the decision to proceed with urgent CABG in a patient recently treated with prasugrel should be based on a personalized risk assessment and might be supported by preoperative platelet function monitoring to shorten the waiting time.

Antithrombotic Therapy in Acute Coronary Syndromes: Current Evidence and Ongoing Issues Regarding Early and Late Management

A few decades ago, the understanding of the pathophysiological processes involved in the coronary artery thrombus formation has placed anticoagulant and antiplatelet agents at the core of the management of acute coronary syndrome (ACS). Increasingly potent antithrombotic agents have since been evaluated, in various association, timing, or dosage, in numerous randomized controlled trials to interrupt the initial thrombus formation, prevent ischemic complications, and ultimately improve survival. Primary percutaneous coronary intervention, initial parenteral anticoagulation, and dual antiplatelet therapy with potent P2Y₁₂ inhibitors have become the hallmark of ACS management revolutionizing its prognosis. Despite these many improvements, much more remains to be done to optimize the onset of action of the various antithrombotic therapies, for further treating and preventing thrombotic events without exposing the patients to an unbearable hemorrhagic risk. The availability of various potent P2Y₁₂ inhibitors has opened the door for individualized therapeutic strategies based on the clinical setting as well as the ischemic and bleeding risk of the patients, while the added value of aspirin has been recently challenged. The strategy of dual-pathway inhibition with P2Y₁₂ inhibitors and low-dose non-vitamin K antagonist oral anticoagulant has brought promising results for the early and late management of patients presenting with ACS with and without indication for oral anticoagulation. In this updated review, we aimed at describing the evidence supporting the current gold standard of antithrombotic management of ACS. More importantly, we provide an overview of some of the ongoing issues and promising therapeutic strategies of this ever-evolving topic.

Inflammatory state does not affect the antiplatelet efficacy of potent P2Y12 inhibitors in ACS

Inflammation leads to atherosclerosis and acute coronary syndromes (ACS). We performed a prospective, observational study to assess association between the concentrations of inflammatory markers (high sensitivity C-reactive protein, hsCRP; high sensitivity interleukin6, hsIL-6; soluble CD40 ligand, sCD40 L) and platelet reactivity in 338 patients with ACS treated with ticagrelor and prasugrel. We also assessed whether hsCRP, hsIL-6, and sCD40 L are associated with standard inflammatory markers (white blood cell [WBC] and fibrinogen), and whether they differ according to patient diabetic status and pre-treatment with statins. Concentrations of hsCRP and concentrations of hsIL-6 and sCD40 L were assessed using turbidimetric assay and enzyme-linked immunosorbent assay, respectively. Platelet reactivity was measured using multiple electrode aggregometry. There was only a weak inverse correlation between hsIL-6 and platelet reactivity (r≤-0.125). In contrast, concentration of hsIL6 and hsCRP positively correlated with WBC and fibrinogen (r ≥ 0.199). Insulin-dependent diabetes mellitus (IDDM) was associated with higher concentration of hsIL-6 (p = .014), whereas pre-treatment with statins - with lower concentration of hsIL-6 (p = .035). In conclusion, inflammatory state does not affect the antiplatelet efficacy of potent P2Y12 inhibitors in the acute phase of ACS, confirming the safety and efficacy of potent P2Y12 inhibitors in patients with a high inflammatory burden.

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.

Impact of mild therapeutic hypothermia on bioavailability of ticagrelor in patients with acute myocardial infarction after out-of-hospital cardiac arrest

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) frequently occurs in the early phase of acute myocardial infarction (MI). Survivors require percutaneous coronary intervention (PCI) with concomitant dual antiplatelet therapy. Target temperature management, including mild therapeutic hypothermia (MTH), should be applied in comatose patients after resuscitation. However, an increased risk of stent thrombosis in patients undergoing hypothermia is observed. The aim of this study was to assess the impact of MTH on pharmacokinetics of ticagrelor in cardiac arrest survivors with MI treated with MTH and PCI.

METHODS

In a prospective, observational, single-center study pharmacokinetics of ticagrelor were evaluated in 41 MI patients, including 11 patients after OHCA undergoing MTH (MTH group) and 30 MI patients without OHCA and MTH (no-MTH group). Blood samples were drawn before administration of a 180 mg ticagrelor loading dose, and 30 min, 1, 2, 4, 6, 12, and 24 h after the loading dose.

RESULTS

In patients treated with MTH total exposure to ticagrelor during the first 12 h after the loading dose and maximal plasma concentration of ticagrelor were significantly lower than in the no-MTH group (AUC(0-12): 3403 ± 2879 vs. 8746 ± 5596 ng·h/mL, difference: 61%, p = 0.01; Cmax: 475 ± 353 vs. 1568 ± 784 ng/mL, p = 0.0002). Time to achieve maximal ticagrelor plasma concentration was also delayed in the MTH group (tmax for ticagrelor: 12 [6-24] vs. 4 [2-12] h, p = 0.01).

CONCLUSIONS

Bioavailability of ticagrelor was substantially decreased and delayed in MI patients treated with MTH after OHCA.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02611934.

Clopidogrel in Critically Ill Patients

Only limited data are available regarding the treatment of critically ill patients with clopidogrel. This trial investigated the effects and the drug concentrations of the cytochrome P450 (CYP450) activated prodrug clopidogrel (n = 43) and the half‐life of the similarly metabolized pantoprazole (n = 16) in critically ill patients. ADP‐induced aggregometry in whole blood classified 74% (95% confidence intervals 59–87%) of critically ill patients as poor responders (n = 43), and 65% (49–79%) responded poorly according to the vasodilator‐stimulated phosphoprotein phosphorylation (VASP‐P) assay. Although the plasma levels of clopidogrel active metabolite normally exceed the inactive prodrug ∼30‐fold, the parent drug levels even exceeded those of the metabolite 2‐fold in critically ill patients. The half‐life of pantoprazole was several‐fold longer in these patients compared with reference populations. The inverse ratio of prodrug/active metabolite indicates insufficient metabolization of clopidogrel, which is independently confirmed by the ∼5‐fold increase in half‐life of pantoprazole. Thus, high‐risk patients may benefit from treatment with alternative platelet inhibitors.