Adverse Drug Reactions

Question 1

Which of the following characteristics is TRUE about Type A (Augmented) adverse drug reactions?

A. Unpredictable and unrelated to pharmacological action
B. Often immune-mediated and delayed
C. Typically dose-dependent and predictable
D. Commonly linked to genetic abnormalities such as G6PD deficiency

Answer 1

C
Explanation: Type A reactions are predictable, related to pharmacological action, and often dose-dependent.

Question 2

Which of the following is an example of a Type B (Bizarre) adverse drug reaction?

A. Sedation from diazepam
B. Hypoglycemia from insulin
C. Respiratory depression from morphine
D. Hemolysis in a G6PD-deficient patient after taking antimalarials

Answer 2

D
Explanation: Type B reactions are unpredictable, and G6PD-related hemolysis is a classic example.

Question 3

What is the most appropriate management for a Type B adverse drug reaction?

A. Increase the dose gradually
B. Titrate to lowest effective dose
C. Monitor closely and reduce dose if needed
D. Discontinue the drug immediately

Answer 3

D
Explanation: Type B reactions are unpredictable and potentially life-threatening—discontinuation is key.

Question 4

Which of the following statements best differentiates Type A and Type B adverse reactions?

A. Type A reactions are immune-mediated; Type B are not
B. Type B reactions are more common but less severe than Type A
C. Type A reactions can be detected post-marketing, while Type B are found early
D. Type A reactions are usually dose-related, whereas Type B are not clearly dose-related

Answer 4

D
Explanation: Type A = dose-dependent; Type B = often not dose-related and unpredictable.

Question 5

Which of the following adverse effects is MOST LIKELY a Type A reaction?

A. Stevens-Johnson Syndrome with allopurinol
B. Tremor with salbutamol
C. Anaphylaxis from penicillin
D. Hemolysis with sulfa drugs in G6PD-deficient patients

Answer 5

B
Explanation: Tremor is a known, pharmacologically predictable effect of β2-agonists.

Question 6

Different types of Type B Hypersensitivity Reactions’ Immune Reactant and antigen form

Answer 6

Type I - IgE (Soluble Antigen)
Type II - IgG or IgM (Cell-bound Antigen)
Type III - Ig G and IgM (Souble Antigen)
Type IV - T cells (Soluble or Cell-bound antigen)

Question 7

Type B Hypersensitivity Type I - MOA
- Examples

Answer 7

MOA
- Antibody-mediated hypersensitivity
- Allergen Exposure, IgE production and binding to mast cells, degranulation and release of histamine

Eg Local and Systemic Anaphylaxis, seasonal hay fever, food/drug allergies

Question 8

Type B Hypersensitivity Type II
- MOA
- Examples

Answer 8

MOA
- Drug binds to cell surface proteins (on platelets or neutrophils)
- Complex = Recognized as foreign, IgG/IgM antibodies form
- Leads to cell destruction

Eg RBC destruction after mismatched transfusion or during hemolytic disease of newborn

Question 9

Type B Hypersensitivity Type III
- MOA
- Examples

Answer 9

MOA
- Antigen-antibody complexes (IgG/IgM form in circulation
- Deposit in tissues, Activate Complement, Inflammation and tissue damage

eg Rheumatoid arthritis, SLE

Question 10

Type B Hypersensitivity Type IV
- MOA
- Examples

Answer 10

MOA
- T-cell mediated (No antibodies)
- T cells recognize and react to antigen > release cytokines > recruit macrophages > delayed inflammation (48-72hrs)

Eg Contact Dermatitis, T1 DM, Multiple Sclerosis

Question 11

Severity of ADR

Answer 11

Mild
- No antidote or treatment is required
- Hospitalization is not prolonged

Eg ACE inhibitor: Cough
Antidepressants: Dry Mouth
Antihistamine: Drowsiness
_____
Moderate
- Change in treatment (Modified dosage, addition of a drug) but not necessarily discontinuation of drug
- Hospitalization may be prolonged
- Specific treatment may be required

eg Hormonal contraceptives: Venous thrombosis
NSAIDs: Hypertension and Oedema
Opioids: Constipation
____

Severe
- Potentially life-threatening and requires discontinuation of the drug and specific treatment

Eg ACE inhibitor: Angioedema
Macrolide antibiotics: Abnormal heart rhythm
_____
Lethal
- Directly or indirectly contributes to a patient’s death

Eg Acetaminophen overdose: Liver Failure
Anticoagulants: Haemorrhage

Question 12

Drug-induced Dermatologic Disease

True Drug Allergy VS Drug Hypersensitivity

Answer 12

True Drug Allergy
- Involves immune system and body needs to have seen the drug before to react, Antibodies or T-cells involved

Drug Hypersensitivity
- No immune system involved. Reaction due to direct effect of drug on mast cells, complement etc. Happens on first-dose

Question 13

When is Type A (Augmented) VS Type B (Bizarre) - Detection

Answer 13

A - Early in clinical development
B - Post-licensing (Uncommon and unpredictable)

Question 14

Differentiate between Type A and Type B adverse drug reactions. Provide one clinical example for each.
(5 marks)

Answer 14

Type A (Augmented): Predictable, dose-related reactions due to known pharmacological effects.

Example: Hypoglycemia from insulin.

Type B (Bizarre): Unpredictable, not dose-dependent, often immune-mediated (Type I–IV hypersensitivity) or idiosyncratic.

Example: Stevens-Johnson Syndrome from carbamazepine.

Type A is more common and typically managed by dose adjustment, whereas Type B often requires discontinuation of the drug.