Drug Toxicity and Poisoning
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What type of reaction is mediated by IgG and involves tissue deposition of drug-antibody complexes with complement activation and inflammation?

  • Type IV: Delayed Hypersensitivity Reactions
  • Idiosyncratic Reactions
  • Type I: Anaphylaxis
  • Type III: Arthus Reactions (correct)

    • What is the result of the combination of a hapten with a larger carrier such as a protein?

  • Activation of complement and lysis of cells
  • Production of antibodies that bind specifically to the carrier
  • Phagocytosis by natural killer cells and macrophages
  • Production of antibodies that bind specifically to the hapten (correct)

    • What is the timing of a Type III reaction?

  • 2 to 7 days after cutaneous drug exposure
  • Variable, may take hours to a day
  • Immediate, occurring within minutes
  • 1 to 3 weeks after drug exposure (correct)

    • What is the main mechanism of Type IV reactions?

    <p>Inflammatory reaction generated by the production of cytokines</p> Signup and view all the answers

    What is an idiosyncratic reaction?

    <p>An abnormal reactivity to a chemical that is peculiar to a given individual</p> Signup and view all the answers

    What is the result of the tagging of cells in a hypersensitivity reaction?

    <p>The cells are targeted for destruction by complement activation and lysis</p> Signup and view all the answers

    What is a clinical manifestation of serum sickness?

    <p>Fever, rash, arthralgias, lymphadenopathy, urticaria, and glomerulonephritis</p> Signup and view all the answers

    What type of reaction involves the destruction of RBCs, WBCs, and platelets?

    <p>Immune-mediated destruction</p> Signup and view all the answers

    What is the mechanism of idiosyncratic reactions?

    <p>All of the above</p> Signup and view all the answers

    What is the clinical diagnosis for patients with adverse reactions to two or more structurally unrelated drugs with an underlying immune-mediated mechanism causing the reaction?

    <p>Multiple drug allergy syndrome</p> Signup and view all the answers

    Which type of drug allergy is mediated by IgE antibodies?

    <p>Type I: Anaphylactic Reactions</p> Signup and view all the answers

    Which of the following are considered main targets of Type 1 anaphylactic reactions?

    <p>Respiratory system</p> Signup and view all the answers

    Which of the following statements about the fragment constant (Fc) portion of IgE is true?

    <p>It binds to receptors on mast cells and basophils.</p> Signup and view all the answers

    What is the main mechanism by which anaphylactic reactions cause vasodilation and inflammation?

    <p>Release of histamine, leukotrienes, and prostaglandins</p> Signup and view all the answers

    What type of drug allergy is characterized by IgG or IgM antibodies directed at drug-hapten coated cells?

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

    What type of reaction is termed "immediate hypersensitivity reaction"?

    <p>Type I: Anaphylactic Reactions</p> Signup and view all the answers

    What is the typical timing of anaphylactic reactions after drug exposure?

    <p>Minutes to hours</p> Signup and view all the answers

    What is the primary concern for patients with a history of multiple drug allergies?

    <p>Increased risk of developing new drug allergies</p> Signup and view all the answers

    What does the therapeutic index indicate about a drug?

    <p>It reflects the safety of the drug.</p> Signup and view all the answers

    Which type of adverse drug reactions (ADRs) are predictable and related to pharmacologic actions?

    <p>Dose-dependent reactions</p> Signup and view all the answers

    What accounts for less than 10% of all adverse drug reactions?

    <p>Allergic reactions</p> Signup and view all the answers

    Which factor is NOT a risk factor for drug allergy?

    <p>Generic name of the drug</p> Signup and view all the answers

    What can lead to genotoxic reactions from drugs?

    <p>Injury to DNA</p> Signup and view all the answers

    Which statement about clinical sensitization is true?

    <p>It is difficult to predict based on a drug's chemical structure.</p> Signup and view all the answers

    What is one way in which a drug can cause allergic reactions?

    <p>Previous sensitization via antibody production</p> Signup and view all the answers

    Which route of administration has been associated with severe allergic reactions?

    <p>Intravenous route</p> Signup and view all the answers

    Which of the following is a characteristic of idiosyncratic reactions?

    <p>They develop mainly in susceptible individuals.</p> Signup and view all the answers

    What is a potential outcome of drug interactions?

    <p>Altered rates of absorption</p> Signup and view all the answers

    Which term describes the scenario where two drugs produce an effect that is less than the sum of their individual effects?

    <p>Additive effect</p> Signup and view all the answers

    What is the primary goal when treating poisoning?

    <p>To maintain vital physiological functions</p> Signup and view all the answers

    What is the initial step in decontamination after poisoning?

    <p>Stopping ongoing exposure to the poison</p> Signup and view all the answers

    What technique involves the removal of drugs from the body by filtering the blood extracorporeally?

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

    Which method of gastric emptying can be used in children and adults following poisoning?

    <p>Syrup of Ipecac</p> Signup and view all the answers

    What is a contraindication for the use of syrup of Ipecac?

    <p>Existing or impending CNS depression</p> Signup and view all the answers

    What type of antidote functions by forming an inert complex with a poison?

    <p>Chemical antidote</p> Signup and view all the answers

    Which antidote acts as a glutathione substitute to detoxify hepatotoxic paracetamol metabolites?

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

    How is gastric lavage usually performed in adults?

    <p>With the patient in left-lateral decubitus position</p> Signup and view all the answers

    Which strategy is NOT a primary approach for gastrointestinal decontamination?

    <p>Administration of antibiotics</p> Signup and view all the answers

    Which substance inhibits the metabolism of methanol to its toxic metabolites?

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

    What are toxidromes?

    <p>Groups of physical signs and symptoms associated with specific poisoning syndromes</p> Signup and view all the answers

    What method uses oxygen to bypass toxic effects in cyanide poisoning?

    <p>Toxic effect bypass</p> Signup and view all the answers

    Which antidote is known for competitively displacing poisons from receptor sites?

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

    Which antidote blocks the effects of anti-ChE agents such as organophosphate compounds?

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

    What is the action of thiosulphate in relation to cyanide?

    <p>Accelerates detoxification</p> Signup and view all the answers

    Which type of antidote utilizes a different cellular mechanism to counteract a poison?

    <p>Physiological antidote</p> Signup and view all the answers

    Study Notes

    Toxicology Overview

    • Toxicology studies adverse effects of chemicals on living organisms.
    • Higher therapeutic index indicates a safer drug.

    Adverse Drug Reactions (ADRs)

    • Broadly classified into predictable and unpredictable reactions.
    • Predictable ADRs include dose-dependent reactions and drug interactions.
    • Unpredictable ADRs arise from immunological responses and genetic differences.
    • ADRs contribute to 3% to 6% of hospital admissions and affect 10% to 15% of hospitalized patients.

    Types of Therapeutic Drug Toxicity

    • Dose-dependent reactions: Severity linked to drug concentration and exposure duration.
    • Allergic reactions: Mediated by the immune system, causing less than 10% of ADRs.
    • Idiosyncratic reactions: Unique adverse effects not explained by drug mechanisms.
    • Drug-drug interactions: Altered absorption, binding, biotransformation, or excretion rates.

    Dose Dependent Reactions

    • Include pharmacological (dose-related), pathological (overdose findings), and genotoxic (DNA injury).

    Allergic Reactions

    • Caused by previous sensitization; most reactions occur 1-2 weeks post-exposure.
    • Drug allergy prevalence is low, but misdiagnoses in children are common.

    Risk Factors for Drug Allergy

    • Drug factors: Chemical nature and changes in exposure levels can influence allergy risk.
    • Host factors: Age, underlying health conditions, and previous drug reactions can predispose individuals to allergies.

    Drug Allergy Mechanisms

    • Four categories based on immunological involvement:
      • Type 1: Anaphylactic reactions mediated by IgE, resulting in rapid symptoms.
      • Type II: Cytolytic reactions involving IgG or IgM targeting drug-coated cells.
      • Type III: Arthus reactions characterized by immune complex deposition and delayed symptoms.
      • Type IV: Delayed hypersensitivity reactions mediated by T-lymphocytes.

    Idiosyncratic Reactions

    • Result from abnormal individual reactivity due to genetic factors or enzyme variability.
    • Do not follow typical drug therapy patterns.

    Drug-Drug Interactions

    • Can lead to additive, synergistic, potentiated, or antagonistic effects on pharmacodynamics.

    Prevention of Poisoning

    • Adhere to the “5 Rights” for safe medication administration (right drug, patient, dose, route, and time).

    Principles of Treatment of Poisoning

    • Maintain vital functions while reducing poison concentrations in tissues.
    • Identification of clinical patterns known as toxidromes aids in diagnosis.

    Decontamination Strategies

    • Involves stopping further exposure and employing gastrointestinal decontamination methods (gastric emptying, adsorption, irrigation, catharsis).

    Gastric Emptying Techniques

    • Induced vomiting with syrup of ipecac can generally produce quick emesis, but has contraindications.
    • Gastric lavage involves the insertion of an orogastric tube for stomach content removal.

    Extracorporeal Techniques

    • Techniques include peritoneal dialysis, hemodialysis, or hemoperfusion for certain drug elimination.

    Antidotal Therapies

    • Chemical antidotes neutralize toxins; pharmacologic antidotes compete with poison at receptor sites; physiological antidotes work via different cellular mechanisms.

    Mechanisms of Antidotal Action

    • Inert complex formation, accelerated detoxification, reduced toxic conversion, receptor site competition, receptor site blockade, and toxic effect bypass (e.g., 100% oxygen for cyanide) are key antidotal mechanisms.

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    Description

    A quiz on toxicology, focusing on adverse drug reactions, therapeutic index, and the effects of chemicals on living organisms.

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