## **Core Concept**
Extrapyramidal side effects (EPS) are a group of movement disorders caused by the blockade of dopamine receptors in the brain, particularly in the nigrostriatal pathway. These side effects are commonly associated with the use of antipsychotic medications, which act as dopamine receptor antagonists. The risk of EPS varies among different antipsychotic drugs, with typical antipsychotics having a higher propensity compared to atypical antipsychotics.

## **Why the Correct Answer is Right**
Haloperidol, a typical antipsychotic, is well-known for its high potency and strong dopamine D2 receptor antagonism. This potent blockade of dopamine receptors increases the risk of extrapyramidal side effects, such as dystonia, parkinsonism, akathisia, and tardive dyskinesia. Due to its high potency and affinity for D2 receptors, haloperidol is more likely to cause EPS compared to other antipsychotics listed.

## **Why Each Wrong Option is Incorrect**
* **Option A:** Although risperidone can cause EPS, it is an atypical antipsychotic with a lower risk of EPS compared to typical antipsychotics like haloperidol, especially at lower doses.
* **Option B:** Clozapine is an atypical antipsychotic known for having a very low risk of EPS due to its lower affinity for D2 receptors and higher affinity for other receptors like 5-HT2.
* **Option C:** Olanzapine is another atypical antipsychotic with a relatively low risk of EPS, similar to clozapine, due to its pharmacological profile.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that typical antipsychotics, such as haloperidol, have a higher risk of causing extrapyramidal side effects compared to atypical antipsychotics. This is crucial in clinical practice for selecting the appropriate antipsychotic medication and for monitoring and managing potential side effects.

## **Correct Answer:** D. Haloperidol