Definition, Classification, and Management of Adverse Drug Reactions (ADR)

Definition of Adverse Drug Reactions

An adverse drug reaction (ADR) is an unintended, harmful reaction to a medication administered at normal doses. ADRs can range from mild to severe and can occur due to various physiological, genetic, and drug-related factors.

Classification of ADRs

Type A (Augmented)

Predictable reactions related to the drug’s pharmacological effects. Examples include hypotension from antihypertensives and hypoglycemia from insulin.

Type B (Bizarre)

Unpredictable reactions not related to the drug’s known mechanism, such as allergic responses and anaphylaxis.

Type C (Chronic)

Reactions associated with prolonged drug use, such as nephrotoxicity from analgesics.

Type D (Delayed)

Reactions occurring long after drug exposure, such as teratogenic or carcinogenic effects.

Type E (End-of-use)

Reactions occurring upon discontinuation of the drug, such as withdrawal symptoms.

Management of ADRs

• Recognition: Identifying symptoms related to drug reactions.
• Evaluation: Assessing causality and severity.
• Discontinuation: Stopping or adjusting medication dosage.
• Reporting: Documenting ADRs for pharmacovigilance.
• Alternative Therapy: Finding safer substitutes.
• Patient Education: Informing patients about possible reactions.