Clopidogrel Hypersensitivity: A Novel Multi-Day Outpatient Oral Desensitization Regimen

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.

Ticagrelor Use in a Patient With a Documented Clopidogrel Hypersensitivity

Objective: To report the use of ticagrelor in a patient with a documented hypersensitivity reaction to clopidogrel. Case Summary: A 64-year-old woman presented with non-ST-segment elevation myocardial infarction (NSTEMI) with a history significant for a hypersensitivity reaction to clopidogrel and was medically managed. Based on the patient’s past medical history and current evidence available, the determination was made to use ticagrelor in this patient. Ticagrelor was administered without reaction during the hospital stay and on assessment at 2 and 4 weeks postdischarge. Discussion: Hypersensitivity occurs in approximately 1% of patients receiving clopidogrel. Although the risk of hypersensitivity reaction to clopidogrel is low, evidence to support alternative antiplatelets in this setting is relatively limited. Prasugrel has a similar structure to clopidogrel and, therefore, may cross-react. Furthermore, prasugrel is not recommended in the medical management of NSTEMI. Ticagrelor is a newer P2Y12 inhibitor that contains a cyclopentyltriazolopyrimidine structure. Because of the difference in structure, a lower theoretical risk of cross-reactivity with the thienopyridines would be anticipated. However, there are no reports to date that investigate the use of this agent in patients with a documented thienopyridine allergy. Conclusions: The current case report describes the use of ticagrelor in a patient with documented hypersensitivity to clopidogrel. In this patient, ticagrelor was well tolerated during hospital admission and at 2 and 4 weeks postdischarge following administration.

Outpatient aspirin desensitization for patients with aspirin hypersensitivity and cardiac disease

BACKGROUND

Cardiac disease is common and often treated with aspirin therapy. Patients who develop an immunoglobulin E (IgE) hypersensitivity reaction to aspirin must abort treatment and receive alternative antithrombotic agents. Aspirin desensitization is a therapeutic procedure that may allow patients with a history of hypersensitivity to safely resume aspirin treatment. A variety of inpatient desensitization protocols have been published for IgE-mediated reactions, but outpatient regimens have not been previously reported.

OBJECTIVE

We aimed to determine the efficacy and safety of a multiday outpatient aspirin desensitization protocol for patients with an IgE-mediated aspirin hypersensitivity.

METHODS

We retrospectively assessed the efficacy of a multidose aspirin desensitization protocol performed in a university allergy-immunology clinic between July 2006 and December 2009. Patients were referred for a diagnosis of aspirin hypersensitivity and required aspirin for cardiac disease treatment. The protocol involved 10 or 12 aspirin doses depending on the final dose of 81 or 325 mg. Patients were desensitized over 2 to 3 half-days and were able to return home in between desensitization sessions.

RESULTS

A total of 9 patients with cardiac disease and aspirin hypersensitivity underwent an outpatient multiday aspirin desensitization. Eight patients (89%) were successfully desensitized and 1 patient declined to continue with further desensitization. No adverse reactions requiring inpatient hospital care occurred during desensitization.

CONCLUSIONS

This novel outpatient multiday aspirin desensitization protocol was a safe and effective approach for the treatment of aspirin hypersensitivity in patients with cardiac disease who require aspirin therapy. This flexible protocol is convenient for patients by avoiding hospital admission and full-day time commitments.

Allergic reactions to clopidogrel and cross-reactivity to other agents

Clopidogrel is a widely used antiplatelet agent, particularly after coronary stent implantation. About 1% of patients have allergic or hematologic adverse reactions to clopidogrel. This has important therapeutic implications, as premature discontinuation of clopidogrel is the strongest risk factor for stent thrombosis. Clopidogrel allergy most commonly manifests as a rash. It is important to distinguish this from other causes of rash occurring in patients who have had a recent coronary stent. Although antihistamines and short-term oral corticosteroids are effective in treating most clopidogrel hypersensitivity reactions, some persistent reactions may require discontinuation of clopidogrel. When discontinuation of clopidogrel is required, substitution with an alternative thienopyridine such as ticlopidine traditionally has been performed. However, a recent study suggests that there may be as high as a 27% risk of recurrence of non-life-threatening allergic reactions in such patients, which are usually similar to the allergic reactions that occurred with clopidogrel. No data are available regarding the frequency of cross-reactivity to prasugrel and ticagrelor; these may be potential therapeutic options in some patients.