Radiocontrast Media Reactions
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Questions and Answers

What percentage of adverse drug reactions occur on an allergic or immunologic basis?

  • 15% to 20%
  • 1% to 2%
  • 5% to 10% (correct)
  • 20% to 30%

    • What type of reaction is mediated by drug-specific IgE antibodies?

  • Type I (correct)
  • Type II
  • Type III
  • Type IV

    • What type of reaction results from deposition of immune complexes circulating in the serum?

  • Type I
  • Type II
  • Type III (correct)
  • Type IV

    • What is the fundamental classification used to describe mechanisms of immunologic drug reactions?

    <p>Gell and Coombs classification</p> Signup and view all the answers

    What type of reaction is mediated by diverse cellular mechanisms?

    <p>Type IV</p> Signup and view all the answers

    What type of reaction is mediated by drug-specific IgG or IgM antibodies?

    <p>Type II</p> Signup and view all the answers

    What is the result of diverse mechanisms of immune recognition and activation?

    <p>Drug hypersensitivity reactions</p> Signup and view all the answers

    What is required for the immune system to recognize nonself material?

    <p>Antigens</p> Signup and view all the answers

    What is the approximate percentage of patients that experience reactions with radiocontrast media?

    <p>0.7% to 3%</p> Signup and view all the answers

    What medication is typically used to pre-treat patients with radiocontrast media to reduce the risk of hypersensitivity reactions?

    <p>Prednisone</p> Signup and view all the answers

    What is the primary mechanism of mast cell mediator release by opiates?

    <p>Direct stimulation</p> Signup and view all the answers

    What type of reactions are most common with taxanes, platinum compounds, asparaginases, and epipodophyllotoxins in cancer chemotherapy?

    <p>Type I IgE-mediated reactions</p> Signup and view all the answers

    What is the primary mechanism of anemia caused by platinum compounds?

    <p>Cytotoxic immunologic mechanism</p> Signup and view all the answers

    What is the purpose of premedicating patients with corticosteroids and H1- and H2-receptor antagonists in cancer chemotherapy?

    <p>To reduce the risk of hypersensitivity reactions</p> Signup and view all the answers

    What is the range of hypersensitivity reactions associated with anticonvulsants?

    <p>Mild maculopapular skin eruptions to severe life-threatening reactions</p> Signup and view all the answers

    What type of reaction is characterized by pruritus and urticaria with occasional mild wheezing?

    <p>Mast cell mediator release directly</p> Signup and view all the answers

    What is the primary step in treating a suspected drug-induced skin reaction?

    <p>Discontinuing the suspected drug as quickly as possible</p> Signup and view all the answers

    What is the recommended treatment for high fever in drug-induced skin reactions?

    <p>Acetaminophen</p> Signup and view all the answers

    What is the typical outcome of maculopapular reactions after discontinuing the causative drug?

    <p>They disappear within a few days</p> Signup and view all the answers

    What is the purpose of topical corticosteroids and oral antihistamines in treating drug-induced skin reactions?

    <p>To relieve pruritus and control symptoms</p> Signup and view all the answers

    What is the primary concern when managing photosensitivity reactions caused by drugs?

    <p>Discontinuing the drug and providing supportive therapy</p> Signup and view all the answers

    What is the goal of avoiding cross-sensitizers in drug-induced skin reactions?

    <p>To prevent recurrence of the skin reaction</p> Signup and view all the answers

    Study Notes

    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.

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    Description

    Learn about the serious reactions caused by radiocontrast media, including hypersensitivity reactions and treatment protocols.

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