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Questions and Answers
What defines an adverse drug reaction (ADR)?
What defines an adverse drug reaction (ADR)?
Which of the following is NOT a type of adverse drug reaction?
Which of the following is NOT a type of adverse drug reaction?
What onset time defines an acute adverse drug reaction?
What onset time defines an acute adverse drug reaction?
Which severity classification indicates a potentially life-threatening situation?
Which severity classification indicates a potentially life-threatening situation?
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Which type of adverse reaction is characterized as a nonpharmacological response?
Which type of adverse reaction is characterized as a nonpharmacological response?
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How are Type A adverse reactions primarily characterized?
How are Type A adverse reactions primarily characterized?
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Which of the following would be classified as a serious ADR by the FDA?
Which of the following would be classified as a serious ADR by the FDA?
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What is drug intoxication primarily due to?
What is drug intoxication primarily due to?
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What is a significant reason for the higher incidence of ADRs in the elderly?
What is a significant reason for the higher incidence of ADRs in the elderly?
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Which risk factor is particularly concerning during pregnancy with respect to drug use?
Which risk factor is particularly concerning during pregnancy with respect to drug use?
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What is the consequence of chloramphenicol use in newborns?
What is the consequence of chloramphenicol use in newborns?
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What is a common effect of using aspirin in children during a viral infection?
What is a common effect of using aspirin in children during a viral infection?
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In what way can renal insufficiency impact drug therapy?
In what way can renal insufficiency impact drug therapy?
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Which genetic condition increases susceptibility to hemolytic effects of certain drugs?
Which genetic condition increases susceptibility to hemolytic effects of certain drugs?
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What factors can exacerbate the risk of ADRs in elderly patients?
What factors can exacerbate the risk of ADRs in elderly patients?
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Why are breastfeeding infants at risk for ADRs?
Why are breastfeeding infants at risk for ADRs?
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Which type of drug reaction is characterized by low incidence and is often unpredictable?
Which type of drug reaction is characterized by low incidence and is often unpredictable?
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What type of reaction involves effects that are dependent on the duration of treatment?
What type of reaction involves effects that are dependent on the duration of treatment?
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Which type of drug reaction is described as taking time to develop and appearing after drug cessation?
Which type of drug reaction is described as taking time to develop and appearing after drug cessation?
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What describes pseudo-allergic reactions?
What describes pseudo-allergic reactions?
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Which type of reaction is a result of rebound phenomena due to sudden withdrawal?
Which type of reaction is a result of rebound phenomena due to sudden withdrawal?
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What is a common predisposing factor of adverse drug reactions that is intrinsic to the drug?
What is a common predisposing factor of adverse drug reactions that is intrinsic to the drug?
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Which example is correctly associated with Type D drug reactions?
Which example is correctly associated with Type D drug reactions?
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Which of the following factors is NOT linked to intrinsic factors predisposing to adverse drug reactions?
Which of the following factors is NOT linked to intrinsic factors predisposing to adverse drug reactions?
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Study Notes
Adverse Drug Reactions (ADRs)
- An ADR is a noxious and unintended response to a drug at normal doses used for prophylaxis, diagnosis, or treatment.
- ADRs exclude overdose, drug abuse, non-compliance, and medication errors.
- An ADR is harm directly caused by the drug at normal doses during normal use.
Classification of ADRs
-
Onset:
- Acute: Within 60 minutes.
- Sub-acute: 1 to 24 hours.
- Latent: Greater than 2 days.
-
Severity:
- Mild: Bothersome but requires no change in therapy.
- Moderate: Requires change in therapy, additional treatment, hospitalization.
- Severe: Disabling or life-threatening.
-
Type:
- Type A: Exaggerated pharmacological response.
- Type B: Non-pharmacological, often allergic response.
- Type C: Chronic effects, like osteoporosis with oral steroids.
- Type D: Delayed effects, like teratogenic effects.
- Type E: End-of-use effects, like withdrawal syndrome.
- Type F: Failure of efficacy (no response), like resistance to antimicrobials.
Type A (Augmented) Reactions
- Predictable reaction that is an exaggerated pharmacological response.
- Drug intoxication occurs due to an exaggerated drug effect.
- Drug toxicity can occur due to increased drug dose or decreased drug elimination leading to increased drug concentration in the blood.
- Can be predicted from the known pharmacology of the drug.
- Dose-dependent reactions.
- Account for 75% or more of ADRs.
- High incidence.
- Dose-related reactions can be reproduced in animals.
- Can be managed and are largely avoidable with care.
Type B (Bizarre) Reactions
- Unpredictable and not part of the normal pharmacology of the drug.
- Rare and occurs only in some people (low incidence).
- Account for most drug fatalities.
- May not be discovered until the drug is used in many patients.
- Often allergic, but sometimes associated with congenital enzyme deficiencies.
- Examples: Chloramphenicol and bone marrow suppression leading to aplastic anemia (late onset: 3-6 weeks after use).
Immunological Reactions
- IgE-mediated allergic reaction in sensitized patients.
Pseudo-allergic Reactions
- Mimic allergic reactions but have no immunological basis.
- Not due to IgE release, but due to direct mast cell activation.
- Example: Asthma and skin rashes with aspirin.
Type C (Continuous or Chronic) Reactions
- Adverse effects related to the duration of treatment, involving dose accumulation.
- Example: Antimalarials and ocular toxicity.
Type D (Delayed) Reactions
- Dose-independent.
- Take time to develop and may appear after stopping the drug.
- Examples:
- Carcinogenicity (e.g., immunosuppressants).
- Teratogenicity (e.g., fetal hydantoin syndrome caused by phenytoin).
Type E (Ending of Use) Reactions
- Adaptive changes:
- Examples: Tolerance and physical dependence (narcotic analgesics).
- Rebound Phenomena:
- When adaptive changes occur during long-term therapy (Type C), sudden withdrawal of the drug may result in rebound reactions.
- Example: Corticosteroids causing acute adrenal insufficiency.
Predisposing Factors of ADRs
-
Non-drug factors:
- Intrinsic to the patient: Age, sex, genetics, tendency to allergy, disease, personality & habits.
- Extrinsic to the patient: The environment.
-
Drug factors:
- Intrinsic to the drug.
- Includes simultaneous use of several different drugs and Drug-drug interactions (multiple medications).
ADR Risk Factors
- Age (children and elderly).
- Pregnancy and breastfeeding.
- Genetic predisposition.
- Multiple medications.
- Concurrent diseases (renal, liver, cardiac).
- End-organ dysfunction.
- Inappropriate medication prescribing, use, or monitoring.
- Prior history of ADRs.
- Extent of exposure (dose and duration).
Risk Factors Examples: Age-Related Issues
- ADRs, including drug interactions, are a common cause of hospital admission in the elderly.
- Reasons for ADRs in the elderly:
- Concomitant use of several medications.
- Disease states leading to drug ADME changes.
- Decreased drug ADME activity due to age.
- These conditions are exacerbated by malnutrition and dehydration, which are common in the elderly.
ADR Frequency by Drug Use
- The more medications in a regimen, the greater the likelihood of an ADR.
Infants and Young Children
- Infants and young children are at high risk of ADRs because their ability to metabolize drugs is not fully developed.
- Example:
- Newborns cannot metabolize chloramphenicol, causing gray baby syndrome (hypotension and cyanosis) - a serious and fatal reaction.
- Children are at risk of developing Reye syndrome if given aspirin during a viral infection.
Risk Factors Examples: Pregnancy
- Use of sulfonamides (antibiotic) can lead to jaundice and brain damage in the fetus.
- Warfarin use for anticoagulation can lead to birth defects and an increased risk of bleeding problems in newborns and mothers.
- Lithium, for psychiatric disorders, can lead to defects of the heart, lethargy, reduced muscle tone, and underactivity of the thyroid gland.
Risk Factors Examples: Breastfeeding
- Similar concerns as for other children with underdeveloped capability to metabolize or excrete drugs.
- Many drugs can be passed from mother to infant via breast milk:
- Amantadine (antiviral)
- Cyclophosphamide (antineoplastic)
- Cocaine (Schedule 2 FDA drug)
Risk Factors Examples: Disease States
- Metabolism may be impaired with hepatic disease:
- Cirrhosis
- Hepatic Carcinoma
- Elimination may be impaired with renal insufficiency:
- Acute or chronic renal failure.
- Decreased glomerular filtration rate (GFR).
- Drug levels may become toxic if too high, so dosing modifications may be indicated.
Risk Factors Examples: Genetic Differences
- Glucose 6 phosphate dehydrogenase deficiency (G6PD) renders patients more susceptible to the hemolytic effect of drugs.
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