Clopidogrel Administration Impairs Post-Stroke Learning and Memory Recovery in Mice

Clopidogrel, which is one of the most prescribed antiplatelet medications in the world, is given to stroke survivors for the prevention of secondary cardiovascular events. Clopidogrel exerts its antiplatelet activity via antagonism of the P2Y12 receptor (P2RY12). Although not widely known or considered during the initial clinical trials for clopidogrel, P2RY12 is also expressed on microglia, which are the brain's immune cells, where the receptor facilitates chemotactic migration toward sites of cellular damage. If microglial P2RY12 is blocked, microglia lose the ability to migrate to damaged sites and carry out essential repair processes. We aimed to investigate whether administering clopidogrel to mice post-stroke was associated with (i) impaired motor skills and cognitive recovery; (ii) physiological changes, such as survival rate and body weight; (iii) changes in the neurovascular unit, including blood vessels, microglia, and neurons; and (iv) changes in immune cells. Photothrombotic stroke (or sham surgery) was induced in adult male mice. From 24 h post-stroke, mice were treated daily for 14 days with either clopidogrel or a control. Cognitive performance (memory and learning) was assessed using a mouse touchscreen platform (paired associated learning task), while motor impairment was assessed using the cylinder task for paw asymmetry. On day 15, the mice were euthanized and their brains were collected for immunohistochemistry analysis. Clopidogrel administration significantly impaired learning and memory recovery, reduced mouse survival rates, and reduced body weight post-stroke. Furthermore, clopidogrel significantly increased vascular leakage, significantly increased the number and appearance of microglia, and significantly reduced the number of T cells within the peri-infarct region post-stroke. These data suggest that clopidogrel hampers cognitive performance post-stroke. This effect is potentially mediated by an increase in vascular permeability post-stroke, providing a pathway for clopidogrel to access the central nervous system, and thus, interfere in repair and recovery processes.

Efficacy, Safety, and Role of Antiplatelet Drugs in the Management of Acute Coronary Syndrome: A Comprehensive Review of Literature

Acute coronary syndrome (ACS) is a complex condition characterized by myocardial ischemia or infarction which can lead to significant morbidity and death. Antiplatelet drugs play a crucial role in the management of ACS and have been shown to minimize the incidence of significant adverse cardiovascular events and recurrent myocardial infarction (MI). This comprehensive literature review is intended to summarize current information on the effectiveness, safety, and function of frequently used antiplatelet medications in treating ACS. Aspirin, clopidogrel, prasugrel, ticagrelor, abciximab, tirofiban, dipyridamole, cilostazol, and novel antiplatelets are included in the review. Aspirin's effectiveness as a first-line antiplatelet medication in ACS is well established. It has significantly lowered the risk of serious adverse cardiovascular events. Clopidogrel, prasugrel, and ticagrelor are P2Y12 receptor inhibitors found to lower the incidence of recurrent ischemia episodes in ACS patients. Using glycoprotein IIb/IIIa inhibitors such as abciximab, tirofiban, and eptifibatide is effective in managing ACS, especially in high-risk patients. Dipyridamole effectively reduces the risk of recurrent ischemic events in patients with ACS, particularly when used with aspirin. Cilostazol, a phosphodiesterase III inhibitor, has also been shown to reduce the risk of major adverse cardiovascular events (MACE) in patients with ACS. Antiplatelet drugs' safety in managing ACS has also been well established. Aspirin is generally well-tolerated with a low risk of adverse effects, although the risk of bleeding events, particularly gastrointestinal bleeding, cannot be eliminated. The P2Y12 receptor inhibitors have been associated with a small increase in the risk of bleeding events, particularly in patients with a high risk of bleeding. The glycoprotein IIb/IIIa inhibitors are associated with a higher risk of bleeding than other antiplatelet drugs, especially in high-risk patients. To summarize, antiplatelet drugs play a crucial role in the management of ACS, and the efficacy and safety of these drugs have been well-established in the literature. The choice of antiplatelet drugs will depend on the patient's risk factors, including age, comorbidities, and bleeding risk. The novel antiplatelets may offer new therapeutic options for managing ACS, and further studies are needed to determine their role in managing this complex condition.

Clopidogrel Hypersensitivity: Pathogenesis, Presentation and Diagnosis

This paper provides an overview of the pathogenesis, presentation and diagnosis of clopidogrel hypersensitivity. The majority of clopidogrel hypersensitivity cases are due to a T cell mediated Gell and Coombs Type IV reaction. History, histology, and patch testing have shown consistency with a T cell mediated mechanism. Clopidogrel reactions most commonly present as a mild delayed maculopapular erythematous rash 5 to 10 days after introduction of the drug, and do not always require discontinuation of the drug. Severe cutaneous, systemic, and immediate adverse reactions to clopidogrel are rare. For the diagnosis of clopidogrel hypersensitivity, drug causality can be determined using patch testing, or for mild reactions, recurrence of symptoms after drug reintroduction, although neither are required for diagnosis.

Clopidogrel Desensitization: Background and Recommendations for Use of a Rapid (4 Hour) Protocol

The purpose of this section is to educate the reader on how to successfully manage patients with a hypersensitivity reaction to clopidogrel using desensitization protocol based on various published protocols. Additionally, we will define drug desensitization, and describe the possible mechanism of how desensitization may function as alternative medication. The indications/contraindications for desensitization will be reviewed. The different published clopidogrel desensitization protocols will be discussed. Based on those protocols, we recommend a protocol we feel is safe and efficacious. Clopidogrel is a thienopyridine antiplatelet drug widely used for treatment and also employed for secondary prevention regarding a range of cardiovascular diseases. However, it has been reported to cause hypersensitivity reactions. Ticlopidine is an alternative medication that can be considered when patients have an allergic reaction to clopidogrel. Additionally, ticlopidine is associated with increased risk causing potentially life-threatening adverse reactions to include: Aplastic anemia, reversible neutropenia, and thrombotic thrombocytopenia purpura vs. clopidogrel. Thus, clopidogrel desensitization offers an attractive alternative. Drug desensitization is defined as causing a temporary state of tolerance to a specific medication responsible for a hypersensitivity reaction. Furthermore, drug desensitization can only be maintained by continuous administration of this drug. Discussion: The exact immunologically mediated mechanism of how rapid oral desensitization works is not fully understood and yet to be defined. Ultimately desensitization results in causing antigen-specific mast cell tolerance. Various protocols have been published. The length of desensitization ranged from 2 h using 9 doses to 7 h using 15 doses. Recommendations: Taking the above into account, we recommend using a modification to the protocol that has the largest number of patients to undergo a standardized clopidogrel desensitization. This approach is shorter, as time has immense importance for these patients. Dosing starts at 10 mg dose and with 60 min intervals between doses, this now becomes a 4 h desensitization protocol.

Comparing Allergist and Cardiologist Considerations for the Optimal Management of Thienopyridines Hypersensitivity

BACKGROUND AND OBJECTIVE

The thienopyridine family includes ticlopidine, clopidogrel and prasugrel which are antiplatelet drugs largely used, mainly associated to aspirin, for treatment of acute coronary syndromes and after percutaneous coronary interventions, to avoid thrombosis. In some patients, thienpyridines may cause hypersensitivity reactions which jeopardize the optimal therapeutic and preventive approach to vascular diseases. The management of thienopyridine hypersensitivity seems to be best done as an interdisciplinary collaboration between the allergist and cardiologist.

METHOD

The present study investigates the management of thienopyridines hypersensitivity on the basis of published case reports and studies, comparing the pro and contro of pharmacological treatments, different desensitization protocols to thienopyridines and substitution of antiplatelet agents eaches others, according to the point of view of cardiologist and allergist. For the cardiologist, the important issues are the necessity of continuing therapy, the desired duration of therapy based on the clinical indication of the individual patient and appropriateness of using one of the alternative P2Y12 inhibitors. For the allergist, the important issues are weighing the risk and benefits of the various therapeutic options: treating "through" desensitization, or switching to an alternative agent.

RESULTS AND CONCLUSION

All the data seem to suggest that only working together, a cardio-allergy team of specialists may evaluate and offer the best approach to clinical decision-making for the individual patient.

Use of Alternative Antiplatelet Agents for Clopidogrel Hypersensitivity

Clopidogrel is a widely used agent for secondary prevention of vascular events and is a cornerstone of dual antiplatelet therapy in patients with acute coronary syndrome (ACS) post coronary stent implantation. Hypersensitivity reactions to clopidogrel are well documented and may range from localized to systemic in presentation. This can lead to discontinuation of therapy, thus increasing the risk of vascular events. The authors have developed recommendations for potential alternative agents for the management of clopidogrel hypersensitivity reactions. Proposed strategies include treatment with an alternative P2Y12 inhibitor, cilostazol or warfarin.

A joint allergist/cardiologist classification for thienopyridines hypersensitivity reactions based on their symptomatic patterns and its impact on the management strategies

The role and importance of thienopyridines such as ticlopidine, clopidogrel, and prasugrel is well-established for several indications, ranging from prevention of acute coronary syndromes to percutaneous coronary interventions, where the dual antiplatelet therapy represents the gold standard to avoid denovo coronary stenosis. However, there is a significant cohort of patients with coronary artery disease who may manifest hypersensitivity reactions to thienopyridines. The examination of the various case reports from medical literature leads to identify mainly four clinical patterns of hypersensitivity to thienopyridines which involves more frequently cutaneous, hematologic, and articular tissues, therefore the kind and predominance of clinical symptoms may determine a different clinical approach to overcome or neutralize thienopyridines hypersensitivity.

Prasugrel hypersensitivity with respiratory distress and rash

Purpose

An adverse drug reaction associated with the use of prasugrel for dual antiplatelet therapy after percutaneous coronary intervention (PCI) with stent placement is reported.

Summary

About one week after starting prasugrel use following angioplasty and a stent revision procedure, a 61-year-old woman arrived in the emergency department with wheezing, shortness of breath, a feeling of throat closure, and a widespread erythematous, maculopapular, pruritic rash. She reported that the respiratory symptoms had started to develop the previous day, with the onset of rash occurring about 24 hours after initiation of prasugrel therapy. The patient’s symptoms subsided after administration of 0.3 mg epinephrine subcutaneously, diphenhydramine 50 mg i.v., and methylprednisolone 125 mg i.v. Prasugrel was discontinued, and the patient was switched to another P2Y12 inhibitor (ticagrelor) for continued dual antiplatelet therapy. Analysis of the case using the adverse drug reaction probability scale of Naranjo et al. indicated that prasugrel was the probable cause of the hypersensitivity reaction. Hypersensitivity manifesting as a rash has been previously reported in patients receiving prasugrel, a thienopyridine P2Y12 inhibitor. Desensitization may be an option for thienopyridine-allergic patients undergoing PCI with stenting; alternatively, the nonthienopyridine P2Y12 inhibitor ticagrelor may be used in a dual antiplatelet therapy regimen.

Conclusion

A patient who had undergone PCI with stenting developed shortness of breath and rash associated with prasugrel therapy. Symptoms abated after supportive therapy and discontinuation of prasugrel, the probable offending agent. Treatment was safely switched to ticagrelor.

Oral antiplatelet agent hypersensitivity and cross-reactivity managed by successful desensitisation

Oral platelet aggregation inhibitors are widely used for the treatment and prevention of cardiovascular diseases, including coronary stent thrombosis. Premature discontinuation following percutaneous coronary intervention would pose a grave risk of in-stent thrombosis, acute myocardial infarction and eventual death. Although they share the same mechanism of adenosine diphosphate P2Y12 platelet receptor inhibition, they belong to either the chemical class of thienopyridines (clopidogrel, prasugrel, and ticlopidine) or cyclopentyl-triazolo-pyrimidines (ticagrelor and cangrelor). This case describes the first documented cross-reactive hypersensitivity of clopidogrel towards both its fellow thienopyridine, prasugrel, as well as the structurally dissimilar ticagrelor, and its subsequent successful desensitisation.