22 Questions
What percentage of all ADRs are on-target (predictable) reactions?
80%
Which of the following is an example of an off-target (unpredictable) reaction?
Urticaria due to penicillin
What is the characteristic of on-target (predictable) reactions in terms of dose?
Dose-dependent
What is the term for ADRs that occur on reexposure to a drug or during the second week of a course of treatment?
Antibody-mediated reactions
What is the characteristic of antibody-mediated (immunologic) reactions in terms of dose?
Occur at lower doses than required for pharmacologic effect
What is the term for ADRs that can be explained by the known pharmacology of the drug?
On-target reactions
According to Health Canada, what is an adverse reaction to?
Health products including drugs, medical devices, and natural health products
What is an example of a secondary effect of a drug?
Development of diarrhea with antibiotic treatment
What percentage of hospitalized patients will experience an adverse drug reaction?
30% to 40%
What is the term for ADRs that do not exhibit a simple relationship between dose and occurrence of toxicity?
Off-target reactions
What is the estimated annual cost of adverse drug reactions on healthcare?
$136 billion
What is the ranking of adverse drug reactions as a cause of death?
Fifth leading cause
What is the primary challenge in determining whether a reaction is an adverse drug reaction?
All of the above
What is the goal of causality assessment in adverse drug reactions?
To determine the probability of association between the drug and the reaction
When did the reaction occur in relation to the drug is an important question in causality assessment because it helps to
Establish a temporal relationship between the drug and the reaction
What is the purpose of stopping the suspected drug or providing specific treatment in causality assessment?
To determine the probability of association
What percentage of ADRs leading to outpatient visits are caused by antibiotics?
16.1%
Which of the following is NOT a common cause of ADRs leading to hospital admission?
Antineoplastics
What is the percentage of ADRs leading to ED visits caused by opioids?
6.8%
Which of the following excipients may cause ADRs in patients with hypersensitivity?
Carboxymethylcellulose
What is the percentage of ADRs leading to hospital admission caused by warfarin?
11%
According to Pirmohamed et al., what percentage of ADRs are caused by diuretics?
27%
Study Notes
Adverse Drug Reactions (ADRs)
- ADRs are undesirable effects to health products, including drugs, medical devices, and natural health products.
- According to Health Canada, ADRs include both prescription and non-prescription pharmaceuticals.
- WHO defines ADRs as any noxious and unintended response to a medicinal product.
Importance of ADRs
- ADRs are common, affecting 30% of hospitalized patients.
- ADRs are expensive, with an estimated annual healthcare cost of $136 billion.
- ADRs can be serious, with serious/fatal reactions being the fifth leading cause of death.
- ADRs are often preventable.
Recognizing ADRs
- ADR detection can be easy or challenging, depending on the patient's medication history and other complicating factors.
- Causality assessment is necessary to determine the probability of association between the drug and the reaction.
Causality Assessment
- Determine the probability of association by considering:
- When did the reaction occur in relation to the drug?
- Did the reaction occur only after the drug was started?
- Did anything else change around the time of the ADR?
- Did the reaction improve when the drug was stopped or specific treatment given?
- Was there ever intentional or accidental use of the drug following the ADR?
Drugs Causing ADRs
- Outpatient leading to admission to hospital:
- NSAIDs (30%)
- Diuretics (27%)
- Warfarin (11%)
- ACEI/ARBs (8%)
- Antidepressants (7%)
- Beta-blockers (7%)
- Opioids (6%)
- Outpatient leading to ED visits:
- Anticoagulants (17.6%)
- Antibiotics (16.1%)
- Diabetes agents (13.3%)
- Opioids (6.8%)
- Antiplatelets (6.6%)
- Consider excipients, especially in patients with hypersensitivity to systemic corticosteroids, vaccines, and biologics.
Classification of ADRs
- Predictable Reactions ("on-target" ADRs):
- Augmentation of the pharmacology of the drug
- Dose-dependent
- 80% of all ADRs
- Unpredictable Reactions ("off-target" ADRs):
- Cannot be explained by the known pharmacology of the drug
- Do not exhibit a simple relationship between dose and occurrence of toxicity
Predictable Reactions
- Examples:
- Toxicity: hepatic failure with high-dose acetaminophen
- Side effect: sedation with antihistamines
- Secondary effect: development of diarrhea with antibiotic treatment
- Drug interaction: theophylline toxicity with concomitant erythromycin
Unpredictable Reactions
- Antibody-mediated (immunologic) reactions:
- Occur on reexposure to a drug or during the second week of a course of treatment
- Occur at lower doses than required for pharmacologic effect
- Produce reactions that are characteristic of known allergic drug reactions (e.g., urticaria, angioedema)
- Symptoms usually subside within 3 to 5 days after drug discontinuation
Learn about adverse drug reactions, their classification, and approach to patients experiencing ADRs, including causality assessment and Health Canada's definition.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
