ÎGive patients who experienced previous anaphylactoid reactions to RCM nonionic, iso-osmolar agents and treat them with a premedication regimen that includes systemic corticosteroids and histamine1
receptor antihistamines. This will significantly reduce, but
not eliminate, the risk of anaphylactoid reaction with re-exposure to contrast material. (D)
ÎDelayed reactions to RCM, defined as reactions occurring one hour to one week after administration, occur in approximately 2% of patients. (C) Most are mild, self-limited cutaneous eruptions that appear to be T-cell mediated, although more serious reactions, such as SJS, TEN, and DRESS syndrome have been described.
Aspirin and NSAIDs
ÎOne type of adverse reaction to aspirin/NSAIDs is AERD, a clinical entity characterized by aspirin- and NSAID-induced respiratory reactions in patients with underlying asthma and/or rhinitis or sinusitis. (B)
ÎThe mechanism of AERD appears to be related to aberrant arachidonic acid metabolism. (B)
ÎControlled oral provocation with aspirin is considered to be the most conclusive way to confirm the diagnosis of AERD. (B)
ÎAspirin and NSAIDs that inhibit cyclooxygenase 1 (COX-1) cross-react and cause respiratory reactions in AERD, whereas selective COX-2 inhibitors almost never cause reactions in patients with AERD and can typically be taken safely. (B)
ÎAspirin desensitization followed by daily aspirin therapy to perpetuate the aspirin-tolerant state in patients with AERD is indicated for patients with AERD if aspirin or NSAIDs are therapeutically necessary for treatment of some other condition, such as cardiac or rheumatologic diseases. (D)
ÎAspirin desensitization followed by daily aspirin has been associated with improved outcomes in patients with AERD who are poorly controlled with medical and/or surgical management. (D)
ÎA second reaction type to aspirin and NSAIDs is exacerbation of urticaria and angioedema in approximately 20% to 40% of patients with underlying chronic idiopathic urticaria. (C) Drugs that inhibit COX-1 cross-react to cause this reaction, whereas selective COX-2 inhibitors typically are better tolerated by these patients. (C)
ÎA third reaction type to aspirin and NSAIDs is suggestive of an IgE-mediated mechanism and manifests as urticaria, angioedema or anaphylaxis. It occurs in patients with no underlying respiratory or cutaneous disease. (C) These reactions appear to be drug specific; there is no cross-reactivity with other NSAIDs. (D)
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