Genetically determined abnormal response to a drug is called -

Appeared in: UPPSC 2023

Explanation

Idiosyncrasy is defined as a genetically determined abnormal or peculiar reactivity to a drug.
This type of reaction is not part of the drug's usual pharmacological effects and is uncharacteristic.
It occurs because the individual has a unique genetic feature, often related to drug-metabolizing enzymes, that is not present in the majority of the population.
A classic example is drug-induced hemolytic anemia in patients with a Glucose-6-Phosphate Dehydrogenase (G6PD) enzyme deficiency when they are given drugs like primaquine.

Option A: Teratogenicity refers to the capacity of a drug to cause harm to a developing fetus, resulting in birth defects. It is not a genetically determined reaction of the person taking the drug.
Option B: Carcinogenicity is the ability of a substance to cause or promote the development of cancer. This is a long-term toxic effect, not an immediate, genetically-based abnormal response.
Option C: Poisoning, or toxicity, is a dose-dependent adverse effect. It occurs when the dose of a drug is too high, leading to exaggerated pharmacological actions or tissue damage. It is not specific to a person's genetic makeup.

Clinical Relevance

Nursing practice connection: Knowing Adverse Drug Reactions: Idiosyncrasy helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses should be aware of potential idiosyncratic reactions and should inquire about family history of drug reactions, which can be a clue to genetic predisposition.
The field of pharmacogenomics aims to identify these genetic variations before drug administration to prevent idiosyncratic reactions and allow for personalized drug therapy.
What if the patient developed a rash, hives, and difficulty breathing shortly after taking a new antibiotic? This would suggest an anaphylactic allergic reaction (Type I hypersensitivity), which is an immune-mediated response, not a genetically determined idiosyncratic reaction.

How to Approach the Question

First, identify the key phrase in the question stem: "genetically determined abnormal response."
Next, systematically evaluate each option based on its definition.
Eliminate 'Teratogenicity' as it relates to fetal harm, not the individual's genetic response.
Eliminate 'Carcinogenicity' as it relates to causing cancer, a long-term effect.
Eliminate 'Poisoning' as it is a dose-dependent toxic effect, not a genetic predisposition.
Conclude that 'Idiosyncrasy' is the only term that specifically describes a drug reaction based on an individual's genetic makeup.

Concept Tested & Keywords

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E6 Pharmacology Nurses Shanbhag 3e p. 34-36

E6 Pharmacology KD Tripathi Essentials 9e Part 1 pp. 125-127, 124-126

Practise the full UPPSC 2023

Attempt every question from this paper in a timed mock, then review the full solution for each one.