Effectiveness of switching ‘hyper responders’ from Prasugrel to Clopidogrel after acute coronary syndrome: The POBA (Predictor of Bleeding with Antiplatelet drugs) SWITCH study

Pharmacodynamics During Transition Between Platelet P2Y12 Inhibiting Therapies

Several platelet P2Y₁₂ inhibiting agents, both oral and intravenous, are available for clinical use. The oral P2Y₁₂ inhibitors comprise clopidogrel, prasugrel, and ticagrelor. Cangrelor is the only intravenous P2Y₁₂ inhibitor. Numerous pharmacodynamic studies have been performed to assess the impact of P2Y₁₂ inhibitor switching on platelet reactivity profiles and to define the optimal strategy if switching is needed, with the goal of minimizing the risk of having inadequate platelet inhibition due to potential drug-drug interactions occurring during the drug overlap phase. This article provides an overview of pharmacodynamic studies assessing switching between P2Y₁₂ inhibitors and recommendations on switching modalities based on these findings.

De-escalation of anti-platelet therapy in patients with acute coronary syndromes undergoing percutaneous coronary intervention: a narrative review

Objective:

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y₁₂ receptor inhibitor is the cornerstone of treatment in patients with acute coronary syndromes (ACS) and in those undergoing percutaneous coronary intervention (PCI). In current clinical situation, availability of different oral P2Y₁₂ inhibitors (clopidogrel, prasugrel, and ticagrelor) has enabled physicians to switch among therapies owing to specific clinical scenarios. Although optimum time, loading dose and interval of transition between P2Y₁₂ inhibitors is still controversial and needs further evidence, switching between oral inhibitors frequently occurs in clinical practice for several reasons.

Data sources:

This review was based on data in articles published in PubMed up to June 2018, with the following keywords “antiplatelet therapy”, “ACS”, “PCI”, “ticagrelor”, and “clopidogrel”.

Study selection:

Original articles and critical reviews on de-escalation strategy in ACS patients after PCI were selected. References of the retrieved articles were also screened to search for potentially relevant papers.

Results:

Safety concerns associated with switching between antiplatelet agents, has prompted the use of clopidogrel for patients with ACS especially after PCI as a de-escalation strategy. Practical considerations for de-escalating therapies in patients with ACS such as reducing dose of P2Y₁₂ inhibitors or shortening duration of DAPT (followed by aspirin or P2Y₁₂ receptor inhibitor monotherapy) as potential options are yet to be standardized and validated.

Conclusions:

Current review will provide an overview of the pharmacology of common P2Y₁₂ inhibitors, definitions of de-escalation and different de-escalating strategies and its outcomes, along with possible direction to be explored in de-escalation.

Switching to Clopidogrel in Patients With Acute Coronary Syndrome Managed With Percutaneous Coronary Intervention Initially Treated With Prasugrel or Ticagrelor: Systematic Review and Meta-analysis

Objective: To evaluate the effects of switching from ticagrelor or prasugrel to clopidogrel in acute coronary syndrome (ACS) patients managed with percutaneous coronary intervention on major adverse cardiovascular events (MACEs) and bleeding. Data Sources: We searched MEDLINE, EMBASE, CENTRAL, bibliographies of relevant articles, and clinicaltrials.gov for eligible articles published from inception to January 27, 2019. Study Selection and Data Extraction: We included randomized controlled trials (RCTs) and cohort and case-control studies that reported on ≥1 outcome of interest. Primary outcomes were MACE and major bleeding, and the secondary outcome was any bleeding. Data Synthesis: From 483 articles, we included 7 relevant studies (2 RCTs, 5 cohort studies) at high/unclear risk of bias. Random-effects meta-analysis revealed inconclusive effects on MACE (hazard ratio [HR] = 1.00, 95% CI = 0.59-1.68; I² = 82%), major bleeding (HR = 0.51; 0.19-1.35; I² = 91%), and any bleeding (HR = 0.64; 0.38-1.07; I² = 85%). Similar nonsignificant results were obtained in secondary analyses evaluating risk ratios. Relevance to Patient Care and Clinical Practice: Ticagrelor and prasugrel, are now considered preferred therapy over clopidogrel in patients with ACS. Switching from these potent P2Y₁₂ inhibitors to clopidogrel is commonly performed to reduce bleeding risk, other adverse effects, or costs. Current best-available evidence is inconclusive regarding the effects of switching to clopidogrel on the risk of MACE and bleeding. Overall, studies were underpowered to detect clinically important differences. Conclusions: Until adequately powered trials demonstrate an advantage to switching to clopidogrel from prasugrel or ticagrelor, clinicians may consider this approach as clinically indicated on an individual, case-by-case basis.

Switching P2Y12 Receptor Inhibiting Therapies

Antiplatelet therapy with aspirin and a P2Y₁₂ receptor inhibitor is the cornerstone of treatment of patients with atherothrombotic disease manifestations. Switching between P2Y₁₂ inhibitors occurs commonly in clinical practice for a variety of reasons, including safety, efficacy, adherence, and economic considerations. There are concerns about the optimal approach for switching because of potential drug interactions, which may lead to ineffective platelet inhibition and thrombotic complications, or potential overdosing due to overlap in drug therapy, which might cause excessive platelet inhibition and increased bleeding. This review provides practical considerations of switching based on pharmacodynamic and clinical data available from the literature.

Switching From Ticagrelor or Prasugrel to Clopidogrel

Ticagrelor and prasugrel are newer antiplatelet drugs which, like clopidogrel, block the P2Y12 platelet receptor to inhibit platelet aggregation. Compared with clopidogrel, both ticagrelor and prasugrel have greater clinical efficacy but also have a higher risk of bleeding and are much more costly. Therefore, some institutions and providers switch patients from ticagrelor or prasugrel to clopidogrel in an effort to lower bleeding risk, stem costs, or otherwise ensure that patients can safely adhere to long-term P2Y12 inhibitor therapy. From a pharmacodynamic perspective, switching patients from ticagrelor or prasugrel to clopidogrel comes at a cost of less antiplatelet efficacy. However, it is unclear if antiplatelet efficacy is diminished enough to affect clinical outcomes. This is because clinical trial data investigating such a switch is scant, leaving the clinician unsure as to the acceptability of this practice. Current clinical trial data have thus far not shown any clinical detriment from switching from ticagrelor or prasugrel to clopidogrel, but there are many limitations to these investigations. So although a large-scale switch of patients from ticagrelor or prasugrel to clopidogrel is not recommended, if the patient is unable to adhere to long-term ticagrelor or prasugrel therapy, switching him/her to clopidogrel seems to be a reasonable practice to maintain chronic suppression of platelet aggregation and minimize the risk of ischemic events.

Platelet function testing in contemporary clinical and interventional practice

OPINION STATEMENT

Dual antiplatelet therapy with a combination of aspirin and an inhibitor of the ADP P2Y12 receptor is the recommended treatment for patients with acute coronary syndrome or who are undergoing percutaneous coronary intervention (PCI). However, patients may continue to have ischemic recurrences, including stent thrombosis, which have been linked with the well-known variability in individual response to antiplatelet therapy, and clopidogrel in particular. There are currently several assays available to measure platelet reactivity, and platelet function testing has been shown to be a valuable tool to assess the pharmacodynamic efficacy of antiplatelet drugs. Moreover, platelet reactivity has important prognostic implications, as several studies have shown an association with thrombotic and bleeding events in patients with high and low platelet reactivity, respectively. Consequently, over the past years there has been a plethora of studies investigating the optimal range of platelet reactivity associated with the highest protection against ischemic complications and the lowest risk of bleeding. Given the correlation between on-treatment platelet reactivity and outcomes, the use of platelet function testing has also been advocated to create personalized antiplatelet therapy. Several studies have been conducted in this field, but major clinical trials have failed to demonstrate a benefit of such a strategy in improving clinical outcomes. Indeed, inherent limitations of these trials may have contributed to their failure. The present manuscript provides an overview on the role of platelet function testing in contemporary clinical and interventional practice.