Radiocontrast Media Reactions

Radiocontrast Media

• Radiocontrast media can cause serious, immediate nonimmune hypersensitivity reactions, including urticaria, angioedema, bronchospasm, shock, and death.
• Reactions occur in 0.7% to 3% of patients.
• Typical protocols include pre-treatment with prednisone 50 mg orally 13, 7, and 1 hour(s) before the procedure and diphenhydramine 50 mg orally 1 hour before the procedure.

Opiates

• Opiates (morphine, meperidine, codeine, hydrocodone, and others) stimulate mast cell mediator release directly, resulting in pruritus and urticaria with occasional mild wheezing.
• These reactions are not IgE-mediated, but many patients claim to be "allergic" to one or more of the opiates.
• Pre-treatment with an antihistamine may reduce these reactions, which are rarely, if ever, life-threatening.

Cancer Chemotherapy

• Hypersensitivity reactions have occurred with all chemotherapy agents.
• IgE-mediated type I reactions are the most common.
• Reactions are most common with taxanes, platinum compounds, asparaginases, and epipodophyllotoxins.
• The platinum compounds have produced anemia, probably via a cytotoxic immunologic mechanism.
• Reactions range from mild (flushing and rashes) to severe (dyspnea, bronchospasm, urticaria, and hypotension).
• To reduce the risk, patients are routinely premedicated with corticosteroids and H1- and H2-receptor antagonists.

Anticonvulsants

• A wide range of hypersensitivity reactions, ranging from mild maculopapular skin eruptions to severe life-threatening reactions.

Drug Hypersensitivity

• Drug hypersensitivity reactions collectively encompass immunoglobulin E (IgE)- and non–IgE-mediated (immune and nonimmune) drug hypersensitivity reactions.
• Approximately 5% to 10% of adverse drug reactions occur on an allergic or immunologic basis.

Pathophysiology

• Drug hypersensitivity reactions are a result of diverse mechanisms of immune recognition and activation, resulting in a broad array of clinical findings.
• The Gell and Coombs classification is a framework for considering mechanisms of immunologic drug reactions.
• The classification includes:
  • Type I reactions: Immediate or classic allergic reactions mediated by drug-specific IgE antibodies.
  • Type II reactions: Cytotoxic reactions mediated by drug-specific IgG or IgM antibodies.
  • Type III reactions: Resulting from deposition of immune complexes circulating in the serum.
  • Type IV reactions: Mediated by diverse cellular mechanisms.

Treatment

• If a drug-induced skin reaction is suspected, the most important treatment is discontinuing the suspected drug as quickly as possible and avoiding use of potential cross-sensitizers.
• The next step is to control symptoms (e.g., pruritus).
• Signs or symptoms of a systemic or generalized reaction may require additional supportive therapy.
• For high fever, acetaminophen is more appropriate than aspirin or another NSAID, which may exacerbate some skin lesions.
• Most maculopapular reactions disappear within a few days after discontinuing the agent.
• Symptomatic control of the affected area is the primary intervention.
• Topical corticosteroids and oral antihistamines can relieve pruritus.
• In severe cases, a short course of systemic corticosteroids may be warranted.
• Photosensitivity reactions typically resolve with drug discontinuation.