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Pharmacy Times
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This potentially serious condition is only partially understood, and its triad of symptoms often goes unrecognized.
This potentially serious condition is only partially understood, and its triad of symptoms often goes unrecognized.
Aspirin-exacerbated respiratory disease (AERD) occurs in adults and is somewhat of a misnomer since aspirin sensitivity is not its only component, nor is aspirin the only aggravating analgesic. The Centers for Disease Control indicates that 8.2% of the US population has asthma, and up to 9% of adult asthmatics have this nonallergic hypersensitivity reaction. Patients experience 3 annoying and potentially life-threatening symptoms, dubbed the “Samter triad”—severe chronic rhinosinusitis, nasal polyposis (multiple polyps), and aspirin sensitivity. Onset usually occurs between the ages of 30 and 40 years, although a small number of children develop this condition, and it is more common in women.1
Patients frequently report having had a “never-ending cold,” causing researchers to think that a viral infection may start the inflammatory cascade. AERD patients react to even small doses of aspirin (ASA) and other COX-1 inhibiting nonsteroidal anti-inflammatory drugs (NSAIDs, which include ASA) with nasal congestion and bronchospasm within 30 minutes to 3 hours. Of note, patients can and do react to NSAIDs on the first dose, unlike the situation when an allergy is present and reaction occurs only after a sensitizing dose.2 Most patients are allergy free—and within 2 years, they develop asthma.
AERD creates a considerable burden on the health care system.3 AERD affects more than 30 million Americans and global estimates indicate that AERD costs the health system more than $6 billion.4,5
Why Worry?
Some patients report that the attacks are random and erratic, but NSAIDs usually precipitate acute attacks. Patients may not link their use of NSAIDs to asthma
exacerbations. AERD’ s exacerbations can occur often and may be severe enough to require hospitalization or tracheal intubation. Asthmatic patients with AERD have more compromised lung function and poorer quality of life (QoL) than asthmatics without AERD. Around half of patients need high doses of inhaled corticosteroids or maintenance oral corticosteroids. Corticosteroids decrease QoL may not completely relieve obstruction, and create significant adverse effects.6,7 Formation of nasal polyps is aggressive; polyps may fill the nasal cavity and protrude into the face, causing deformation and mid-facial expansion, or into the nasopharynx, pressuring bones.8,9 Patients then require nasal polypectomy, sometimes repeatedly.7 AERD patients often respond poorly to traditional treatments.
Clinicians frequently fail to recognize this syndrome, so patients are undiagnosed and inadequately treated—a concern for all patients and practitioners.7,10,11
AERD’s mechanism is only partially understood. Researchers have determined that defective eicosanoid metabolism is a known problem. Arachidonic acid breakdown products are directed toward leukotriene production, increasing pro-inflammatory cysteinyl leukotrienes, and away from prostaglandin production, reducing anti-inflammatory prostaglandin E2. NSAIDs, unless selective for COX-2, decrease prostaglandin and thromboxane production, intensifying the shift to leukotriene production. Often, AERD features devastating upper and lower airway eosinophil infiltration.10,14
The gold standard for the diagnosis of AERD is an oral provocation test under close clinical supervision. The challenge test should be performed when asthma is stable (ie, forced expiratory volume in the first second of expiration is >70% of expected value, with a variability of <10%). The supervising clinician administers increasing doses of aspirin every 1.5 to 2 hours, monitoring response carefully. This can be done in an outpatient setting, but is inadvisable unless emergency medication and equipment is available, since life-threatening reactions can occur.15
Managing AERD
There is no cure for AERD. Treatment goals are reduction of inflammation of affected mucosa; prevention of nasal polyp formation; and control of sinusitis, other infections, and asthma.16
AERD patients must avoid NSAIDs and NSAID-containing medications. Pharmacists must educate patients to be vigilant about over-the-counter preparations, which often contain NSAIDs. For analgesia, most patients can take highly selective COX-2 inhibitors.17 Low-dose acetaminophen (<500 mg) poorly inhibits COX-1 and COX-2, but high-dose acetaminophen (>1000 mg) triggers symptoms in more than one-third of patients.18
AERD patients must control their asthma using the most current approaches for their asthma severity (Table 2).
Aspirin desensitization can help some AERD patients with upper and lower airway inflammation. Several studies have demonstrated that desensitization can decrease symptoms, hospitalizations, dependence on corticosteroids, and costs.22-25 Experts recommend desensitization for AERD patients with corticosteroid-dependent asthma, nonresponsive asthma, or those who need NSAID therapy for other conditions including coronary artery disease or chronic arthritis.26
Desensitization starts with a pretreatment with montelukast, then very low dose aspirin for 1 to 5 days, with incremental increases until the patient reacts to a dose. Then that reactive dose is repeated, and the patient generally does not react. Then dose escalation begins again and continues up to 325 mg. The patient goes home on a dose of 325 mg or 650 mg twice a day. Patients take this dose chronically, because resensitization occurs if even a few days are skipped.25,27 The exact mechanism by which desensitization occurs is unclear. Studies are under way to determine the lowest possible aspirin dose that will maintain desensitization.25
Conclusion
More research is needed to understand AERD. Better understanding of its pathogenic mechanism may help develop effective treatments. Disease management requires carefully planned polypharmacy with leukotriene inhibitors, antihistamines, and inhaled or systemic corticosteroids, even if aspirin desensitization is tried and successful.
Ms. Wick is a visiting professor at the University of Connecticut School of Pharmacy and a freelance clinical writer.
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