Adverse Reactions - NAPLEX

1. What is an adverse effect caused by off-target pharmacology at therapeutic doses called?

   Side effect. Side effects occur from unintended activation of non-primary targets at normal doses, differing from toxicities or hypersensitivities.

2. Which opioid adverse reaction is mediated by histamine release rather than IgE allergy?

   Pruritus (pseudoallergy). Opioids directly stimulate mast cell histamine release, causing itch without involving adaptive immune responses or IgE.

3. What is the definition of an idiosyncratic drug reaction?

   Unpredictable, non–dose-related reaction due to host factors. Idiosyncratic reactions depend on genetic or unique patient factors, making them unpredictable and not linked to drug dose or pharmacology.

4. What is the key distinction between an adverse event and an ADR?

   ADR implies causal relationship; adverse event does not. ADRs require evidence of causality between the drug and the reaction, whereas adverse events are any unfavorable occurrences without proven drug linkage.

5. What defines a Type A (augmented) adverse drug reaction?

   Dose-related, predictable, related to pharmacology. Type A reactions stem from exaggerated pharmacological effects, making them foreseeable and often preventable by dose adjustment.

6. Which reaction type is most common: Type A or Type B?

   Type A. Type A reactions account for the majority of ADRs due to their basis in known pharmacological actions and dose dependency.

7. What is the definition of an adverse drug reaction (ADR) per WHO?

   Noxious, unintended response at doses normally used in humans. The WHO definition emphasizes harmful, unintended effects occurring at standard therapeutic doses, distinguishing ADRs from other drug-related issues.

8. What term describes a harmful effect due to excessive dose or accumulation of a drug?

   Toxicity. Toxicity results from supratherapeutic levels overwhelming normal physiological tolerances, often due to overdose or impaired clearance.

9. What is a black box warning intended to communicate about an adverse reaction?

   Risk of serious or life-threatening adverse effects. Black box warnings highlight critical risks identified in post-marketing surveillance or clinical trials to alert prescribers and patients.

10. Which term describes dose-dependent hearing loss and nephrotoxicity from aminoglycosides?

    Type A adverse drug reaction. Aminoglycoside toxicities are extensions of their antibacterial mechanism, accumulating in ears and kidneys with higher doses.

11. Which medication is first-line for anaphylaxis?

    Intramuscular epinephrine. Epinephrine rapidly counteracts vasodilation and bronchoconstriction in anaphylaxis by stimulating alpha and beta adrenergic receptors.

12. Identify the syndrome: fever, rash, eosinophilia, and organ involvement weeks after drug exposure.

    DRESS (drug reaction with eosinophilia and systemic symptoms). DRESS is a delayed hypersensitivity reaction involving T-cell activation, leading to multi-organ inflammation after prolonged drug exposure.

13. Identify the most likely culprit if a patient develops C. difficile diarrhea after antibiotics.

    Clindamycin. Clindamycin potently disrupts gut flora, promoting C. difficile overgrowth and toxin production leading to pseudomembranous colitis.

14. Which adverse reaction is most consistent with facial flushing and hypotension during vancomycin infusion?

    Vancomycin infusion reaction (red man syndrome). Rapid vancomycin infusion causes histamine release from mast cells, resulting in flushing, pruritus, and hemodynamic changes.

15. Identify the severe cutaneous reaction with mucosal erosions and epidermal detachment.

    Stevens-Johnson syndrome/toxic epidermal necrolysis. SJS/TEN results from cytotoxic T-cell responses causing keratinocyte apoptosis and widespread skin and mucosal detachment.

16. Which class is most associated with tendinopathy and tendon rupture as an adverse reaction?

    Fluoroquinolones. Fluoroquinolones disrupt tendon matrix integrity via metalloproteinase upregulation, increasing rupture risk especially in vulnerable populations.

17. What is the definition of an anaphylaxis reaction to a medication?

    Acute, life-threatening systemic hypersensitivity reaction. Anaphylaxis involves rapid IgE-mediated mast cell degranulation, causing widespread histamine release and systemic symptoms.

18. Which medication class is most associated with angioedema as an adverse reaction?

    ACE inhibitors. ACE inhibitors increase bradykinin levels by inhibiting its degradation, triggering vascular permeability and angioedema.

19. What is the term for a reaction that occurs after stopping a drug due to physiologic adaptation?

    Withdrawal reaction. Withdrawal occurs when the body adapts to chronic drug presence, leading to symptoms upon cessation due to disrupted homeostasis.

20. Which adverse reaction is characteristic of succinylcholine in susceptible patients during anesthesia?

    Malignant hyperthermia. Succinylcholine triggers uncontrolled calcium release in genetically susceptible muscle cells, leading to hypermetabolism and hyperthermia.

21. What is the term for worsening symptoms after abrupt discontinuation of a drug (return beyond baseline)?

    Rebound phenomenon. Rebound involves hyperactivation of suppressed pathways after drug removal, causing symptoms to exceed pre-treatment levels.

22. What is the definition of an allergic drug reaction?

    Immune-mediated reaction requiring prior sensitization. Allergic reactions involve immune system activation after initial exposure, leading to hypersensitivity upon re-exposure.

23. Which reaction type is more likely to be serious and require drug avoidance: Type A or Type B?

    Type B. Type B reactions, being idiosyncratic or allergic, often lead to severe outcomes necessitating complete drug avoidance in affected individuals.

24. Which drug adverse reaction is suggested by cough developing after starting lisinopril?

    ACE inhibitor–associated cough. Lisinopril inhibits ACE, elevating bradykinin which irritates airways and induces non-productive cough in susceptible patients.

25. What defines a Type B (bizarre) adverse drug reaction?

    Not dose-related, unpredictable, often immune-mediated. Type B reactions arise from individual hypersensitivity or immunological responses, rendering them hard to predict and unrelated to dose.

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