a male 35 yrs old who is known scizophrenic is on aripiprazole and metaclopramide since 3 months ,now patient was brought to the opd by the attenders complaining patient being static at places while walking and tremors on sitting . what is the drug of choice for the condition developed by the patient ?

**Core Concept**
Aripiprazole, an atypical antipsychotic, can cause extrapyramidal side effects (EPS) such as parkinsonism, akathisia, and dystonia, particularly when combined with metoclopramide, a dopamine antagonist. This combination increases the risk of developing EPS due to its combined effect on the dopaminergic system.

**Why the Correct Answer is Right**
The patient's symptoms of static walking and tremors on sitting suggest parkinsonism, a form of EPS. Metoclopramide's dopamine antagonism exacerbates aripiprazole's effect on the nigrostriatal pathway, leading to parkinsonian symptoms. The drug of choice for treating EPS is an anticholinergic agent, such as trihexyphenidyl, which acts by blocking acetylcholine at muscarinic receptors in the striatum, countering the dopaminergic blockade.

**Why Each Wrong Option is Incorrect**
**Option A:** Haloperidol is a typical antipsychotic that would further worsen EPS due to its strong dopamine blockade.
**Option B:** Benztropine is an anticholinergic but is typically used for treating EPS caused by antipsychotics other than aripiprazole.
**Option C:** Amantadine has some anticholinergic properties but is also a dopamine agonist, which may not be suitable for this patient.

**Clinical Pearl / High-Yield Fact**
When treating EPS, it's essential to consider the specific antipsychotic medication being used and choose an anticholinergic agent that balances efficacy with risk of side effects.

**Correct Answer:** D. Trihexyphenidyl

✓ Correct Answer: D. benzhexol