AIIMS Delhi NO - 2018
Pharmacology
Easy
Which antipsychotic drug causes minimum Extrapyramidal Symptoms (EPS)?
Appeared in: AIIMS Delhi NO - 2018
Explanation
- Clozapine is an atypical antipsychotic with a very low affinity for dopamine D2 receptors, the primary target associated with EPS.
- This unique receptor binding profile results in the lowest incidence of movement-related side effects (EPS) among all available antipsychotics.
- Unlike other antipsychotics where EPS risk can increase with the dose, Clozapine's risk remains minimal even at higher therapeutic doses.
- Due to its low EPS liability, it is a preferred option in patients who have experienced severe EPS with other agents, although its use is limited by other serious side effects.
Why Other Options Were Wrong
- Option B: Haloperidol is a typical (first-generation) antipsychotic that acts as a potent dopamine D2 receptor antagonist. This mechanism is highly effective for psychosis but also leads to a very high risk of causing Extrapyramidal Symptoms.
- Option C: Olanzapine is an atypical antipsychotic with a low risk of EPS, which is significantly lower than that of Haloperidol. However, its risk is still considered higher than that of Clozapine.
- Option D: Risperidone is an atypical antipsychotic that has a moderate, dose-dependent risk of EPS. At lower doses, the risk is low, but as the dose increases (typically above 6 mg/day), it begins to act more like a typical antipsychotic and the risk of EPS rises significantly.
Related Visual
Clinical Relevance
- Nursing practice connection: Use the key finding related to Side effect profiles of antipsychotic medications, specifically Extrapyramidal Symptoms (EPS) to guide bedside assessment, documentation, and the next nursing action.
- Nurses must meticulously monitor patients on any antipsychotic for early signs of EPS (e.g., stiffness, restlessness, tremors) to allow for timely intervention, such as dose adjustment or administration of anticholinergic medication.
- For patients on Clozapine, the primary nursing concern shifts from EPS to monitoring for life-threatening agranulocytosis through mandatory regular blood tests (WBC counts). This is a critical patient safety responsibility.
- What if a patient on Haloperidol develops acute dystonia (a severe, painful muscle spasm and a form of EPS)? The priority nursing action is to ensure patient safety (airway), administer an anticholinergic agent like benztropine or diphenhydramine as ordered, and notify the provider immediately.
How to Approach the Question
- First, identify the core of the question: it asks to find the antipsychotic with the least severe side effect, specifically Extrapyramidal Symptoms (EPS).
- Next, classify the drugs in your mind. Recognize Haloperidol as a typical (first-generation) antipsychotic, which are known for a high EPS risk. Clozapine, Olanzapine, and Risperidone are atypical (second-generation), generally having a lower risk.
- Within the atypical group, recall or deduce the hierarchy of EPS risk. Clozapine is famously known for having the lowest EPS risk but carries the significant risk of agranulocytosis, limiting its use.
- Compare this knowledge to the other atypicals: Risperidone has a notable dose-dependent EPS risk, and Olanzapine's risk is low but still considered higher than Clozapine's.
- Conclude that Clozapine has the minimum risk of EPS among the given options, making it the correct answer.
Concept Tested & Keywords
- Concept Tested: Side effect profiles of antipsychotic medications, specifically Extrapyramidal Symptoms (EPS).
- Stem keywords: antipsychotic drug, minimum, Extrapyramidal Symptoms, EPS
- Lead-in keywords: Which
Question ID
Q6UutBwbJrb3i7S2MzEwqk
Reference Book
E6 Medicine Harrison 22e Part 2 p. 1577-1579
E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 4992-4994
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