Antipsychotic drug with least extra pyramidal symptoms?
**Core Concept**
The question is testing the student's knowledge of antipsychotic medications and their side effect profiles, specifically their propensity to cause extrapyramidal symptoms (EPS). EPS are movement disorders caused by blockade of dopamine D2 receptors in the striatum, a region of the basal ganglia.
**Why the Correct Answer is Right**
The correct answer is Quetiapine, a second-generation (atypical) antipsychotic. Quetiapine has a lower affinity for dopamine D2 receptors compared to other antipsychotics, which reduces its likelihood of causing EPS. Additionally, Quetiapine has a higher affinity for serotonin 5-HT2A receptors, which may contribute to its lower EPS risk.
**Why Each Wrong Option is Incorrect**
**Option A:** Haloperidol is a first-generation (typical) antipsychotic with high affinity for dopamine D2 receptors, making it more likely to cause EPS.
**Option B:** Risperidone is another second-generation antipsychotic, but it has a higher affinity for dopamine D2 receptors than Quetiapine, increasing its risk of EPS.
**Option C:** Olanzapine is a second-generation antipsychotic with a moderate affinity for dopamine D2 receptors, but it is not as low as Quetiapine's, making it a less ideal choice for minimizing EPS.
**Clinical Pearl / High-Yield Fact**
When choosing an antipsychotic for a patient, consider their risk factors for EPS, such as age, comorbid Parkinson's disease, or history of substance abuse. Quetiapine may be a good option for patients with a high risk of EPS, but always weigh the benefits and risks of each medication.
**Correct Answer:** C. Olanzapine