**Question:** Drug of choice in drug induced parkinsonism is

A. Levodopa
B. Amantadine
C. Benztropine
D. Haloperidol

**Correct Answer:** D. Haloperidol

**Core Concept:**
Drug-induced parkinsonism is a set of symptoms that resemble Parkinson's disease, appearing as bradykinesia (slowness of movement), rigidity (stiffness of muscle), tremors, and postural instability, following the use of certain medications. These medications are called neuroleptic drugs, which primarily block dopamine receptors in the brain.

**Why the Correct Answer is Right:**
Haloperidol is a potent antagonist of dopamine D2 receptors, which are primarily involved in the pathogenesis of drug-induced parkinsonism. By blocking these receptors, Haloperidol helps alleviate the symptoms of parkinsonism.

**Why Each Wrong Option is Incorrect:**
A. Levodopa is a precursor to dopamine and is primarily used in the treatment of Parkinson's disease. However, it may worsen parkinsonism symptoms if given to a patient with drug-induced parkinsonism.

B. Amantadine is primarily used in the treatment of Parkinson's disease by enhancing dopamine release, not specifically targeting the dopamine D2 receptors involved in drug-induced parkinsonism.

C. Benztropine is a dopamine D2 antagonist, but it is not specifically targeted to drug-induced parkinsonism. It has broader anticholinergic activity and may not be as effective as Haloperidol in treating this condition.

**Clinical Pearl:**
Haloperidol is the drug of choice in treating drug-induced parkinsonism as it specifically targets the dopamine D2 receptors involved in this condition. In contrast, Levodopa may worsen the symptoms, Amantadine is less specific to the condition, and Benztropine lacks the specificity for drug-induced parkinsonism due to its broader anticholinergic activity.