**Question:** Drug of choice for anti-psychotic induced Parkinsonism

**Core Concept:** Anti-psychotic medications are a class of drugs used to treat mental illnesses, including schizophrenia and bipolar disorder. However, they can cause a side effect known as Parkinsonism, which shares symptoms with Parkinson's disease.

**Why the Correct Answer is Right:** The correct answer, Dantrolene, is a calcium channel blocker that works by preventing calcium release from the sarcoplasmic reticulum in muscle cells. This action helps in managing the extrapyramidal side effects, including Parkinsonism, caused by antipsychotic drugs.

**Why Each Wrong Option is Incorrect:**

A. Haloperidol (Option A): This is a typical antipsychotic drug that can cause Parkinsonism as a side effect. It is not the correct choice for treating Parkinsonism due to its own side effect.

B. Levodopa (Option B): Levodopa is primarily used in the treatment of Parkinson's disease itself, not the side effects caused by antipsychotics. It is ineffective in managing Parkinsonism induced by antipsychotics.

C. Risperidone (Option C): Risperidone is a typical antipsychotic drug that can cause Parkinsonism side effects. Similar to Haloperidol, it is not the correct choice for treating Parkinsonism caused by antipsychotics.

D. Dantrolene (Correct Option): As mentioned before, Dantrolene is a calcium channel blocker that prevents calcium release from the sarcoplasmic reticulum in muscle cells, making it effective in managing extrapyramidal side effects, including Parkinsonism, caused by antipsychotic drugs.

**Clinical Pearl:** When treating patients on antipsychotics and experiencing Parkinsonism side effects, consider prescribing Dantrolene to alleviate the symptoms. However, it is essential to weigh the risks and benefits with the underlying mental health condition, as Dantrolene is not a first-line treatment for Parkinson's disease.

**Correct Answer:** Dantrolene