Which medication is an anticholinergic commonly used to treat an acute dystonic reaction?

• A. Levodopa
• B. Haloperidol
• C. Benztropine
• D. Diazepam

Answer: (C)

Acute dystonic reactions occur when dopamine blockade in the basal ganglia shifts the balance toward acetylcholine activity, producing sudden muscle contractions and abnormal postures. The most effective way to rapidly correct this is with an anticholinergic drug that blocks muscarinic receptors in the brain, restoring the dopamine–acetylcholine balance.

Benztropine is a muscarinic antagonist used specifically for this purpose. By blocking acetylcholine in the CNS, it quickly relieves the painful, involuntary muscle contractions seen in acute dystonia, often within minutes to hours when given by injection, and more gradually when given orally. This makes it the preferred treatment in acute settings.

Levodopa would increase dopaminergic activity, which doesn't address the underlying imbalance and can worsen dystonia. Haloperidol is the offending agent that can cause dystonia. Diazepam can provide comfort through sedation and muscle relaxation but is not the targeted anticholinergic remedy for acute dystonia.