Most common side effect of haloperidol ?
**Core Concept**
Haloperidol is a first-generation antipsychotic medication that belongs to the butyrophenone class. Its primary mechanism of action involves blocking dopamine D2 receptors in the brain, which helps to alleviate symptoms of psychosis. However, this blockade can also lead to various side effects due to the complex interplay between dopamine and other neurotransmitter systems.
**Why the Correct Answer is Right**
The most common side effect of haloperidol is **extrapyramidal symptoms (EPS)**, including dystonia, akathisia, and parkinsonism. This is due to the blockade of dopamine D2 receptors in the nigrostriatal pathway, which is responsible for motor control. The reduction in dopamine activity disrupts the balance between dopamine and acetylcholine, leading to excessive cholinergic activity and the manifestation of EPS. EPS can be managed with anticholinergic medications or dose reduction.
**Why Each Wrong Option is Incorrect**
* **Option A:** Sedation - While sedation is a common side effect of many antipsychotics, it is not the most common side effect of haloperidol. Other first-generation antipsychotics like chlorpromazine are more likely to cause sedation.
* **Option B:** Weight gain - Weight gain is more commonly associated with second-generation antipsychotics like olanzapine and quetiapine. Haloperidol is less likely to cause significant weight gain.
* **Option C:** QT interval prolongation - QT interval prolongation is a risk associated with some antipsychotics, particularly those with QT-prolonging properties like ziprasidone and quetiapine. Haloperidol is not known to significantly prolong the QT interval.
**Clinical Pearl / High-Yield Fact**
EPS are a critical consideration when initiating haloperidol therapy, as they can significantly impact patient quality of life. Early recognition and management of EPS can prevent long-term complications and improve patient outcomes.
**Correct Answer: D. Extrapyramidal symptoms (EPS)**