Combination of aspirin and montelukast (Singulair) decreases hypersensitivity reactions during rapid desensitization

Rapid desensitization is a process in which drug-allergic patients receive their target dose in incremental steps, resulting in a state of temporary tolerance. Consequently, first-line therapy (most commonly antibiotics) can be delivered safely, even in patients who present with severe hypersensitivity reactions (HSRs) to the given agent.

A small subset of patients has persistent HSRs during rapid desensitization that can be refractory to antihistamines and corticosteroids.

A study included 14 patients with HSRs to platinum chemotherapy that persisted during rapid desensitization. The patients were then pretreated with:

- acetylsalicylic acid (asprin) 325 mg orally
- montelukast, 10 mg orally, 2 days before and on the day of desensitization

78 desensitizations in 14 patients were performed. Using acetylsalicylic acid and montelukast, 86% of patients (12/14) experienced substantial improvement in symptoms (grade 0.5 vs grade 2.14). All patients received their target dose of chemotherapy, and there were no severe systemic HSRs.

The authors concluded that pre-treatment with asprin and montelukast lessens the severity of HSRs during rapid desensitization.

Aspirin Desensitization

Aspirin desensitization should only be done in a monitored environment (hospital) in a patient with FEV1 of at least 70% of predicted.

Example protocol: starting dose is 40.5 mg. The dose is doubled over an interval of 1.5 to three hours until the desired daily dose is met. The patient must take the daily dose indefinitely.

Leukotriene antagonist (LTRA, Singulair) should be initiated prior to the procedure.

Aspirin desensitization can have beneficial effects in patients with aspirin-induced asthma, sinusitis, and can decrease the risk of recurrence of nasal polyps in this population. The desensitized state only lasts as long as daily administration is continued. If a dose is missed, the refractory period may last 48-72 hours.

Acetylsalicylic acid and montelukast block mast cell mediator-related symptoms during rapid desensitization. Breslow RG, Caiado J, Castells MC. Ann Allergy Asthma Immunol. 2009 Feb;102(2):155-60.
Urinary leukotriene E(4)/exhaled nitric oxide ratio predicts montelukast response in childhood asthma
Image source: Coated 325 mg aspirin tablets, Wikipedia, GNU Free Documentation License, Version 1.2.

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