According to Rawlins and Thompson classification, which type of adverse drug reaction is dose-dependent and occurs in individuals with normal drug metabolism?

Question

Accepted Answer

D. Type A (Augmented) reaction. ## Rawlins and Thompson Classification of Adverse Drug Reactions

**Key Point:** Type A reactions are dose-dependent, predictable, and occur in individuals with normal drug metabolism and pharmacokinetics.

### Type A (Augmented) Reactions

- **Definition:** Exaggerated pharmacological response to the drug at normal or high doses
- **Dose-dependent:** Yes — increase in dose increases risk
- **Predictability:** Highly predictable; occur in normal population
- **Mechanism:** Excessive pharmacological effect due to:
  - High drug concentration
  - Individual sensitivity variation
  - Drug-drug interactions
  - Organ dysfunction (renal/hepatic impairment)
- **Examples:**
  - Hypoglycaemia from excessive insulin
  - Bleeding from warfarin overdose
  - Hypotension from antihypertensives
  - Dry mouth from anticholinergics
- **Incidence:** 80% of all ADRs
- **Management:** Dose reduction or drug withdrawal

### Comparison with Other Types

| Feature | Type A | Type B | Type C | Type D |
|---------|--------|--------|--------|--------|
| **Dose-dependent** | Yes | No | No | No |
| **Predictable** | Yes | No | Yes | Yes |
| **Incidence** | 80% | 15% | 3% | 2% |
| **Mechanism** | Pharmacological | Idiosyncratic | Cumulative | Genetic/Delayed |
| **Examples** | Bleeding (warfarin) | Aplastic anaemia (chloramphenicol) | Pulmonary fibrosis (bleomycin) | Phocomelia (thalidomide) |

**High-Yield:** Type A reactions are the most common (80%) and most predictable — they follow the dose-response relationship and can be prevented by dose adjustment or careful monitoring.

**Clinical Pearl:** Type A reactions are reversible upon dose reduction or drug withdrawal, making them less serious than Type B reactions despite being more common.

Answer

A. Type B (Bizarre) reaction

Answer

B. Type C (Chronic) reaction

Answer

C. Type D (Delayed) reaction

According to Rawlins and Thompson classification, which type of adverse drug reaction is dose-dependent and occurs in individuals with normal drug metabolism?

Explanation

Rawlins and Thompson Classification of Adverse Drug Reactions

Type A (Augmented) Reactions

Comparison with Other Types

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Feature	Type A	Type B	Type C	Type D
Dose-dependent	Yes	No	No	No
Predictable	Yes	No	Yes	Yes
Incidence	80%	15%	3%	2%
Mechanism	Pharmacological	Idiosyncratic	Cumulative	Genetic/Delayed
Examples	Bleeding (warfarin)	Aplastic anaemia (chloramphenicol)	Pulmonary fibrosis (bleomycin)	Phocomelia (thalidomide)