Question

A 25 year old man with a psychotic illness was treated with haloperidol 30 mg/day. On the third day he developed pacing and an inability to sit still at one place. Which medication is likely to help?

• A. Phenytoin
• B. Propranolol
• C. Methylphenidate
• D. Trihexyphenidyl

Hint:

Pacing and restlessness on haloperidol is akathisia, not dystonia or parkinsonism, and beta blockers work best for it.

Answer 1

The Correct Option is B

The question describes a man started on a high dose of haloperidol who, within three days, starts pacing and cannot sit still. This is a well-known adverse effect pattern, and the job here is to name it correctly before picking a drug to treat it.

1. Phenytoin: This is used for seizures. It has no place in treating a movement side effect from an antipsychotic, so it does not fit.
2. Propranolol: A beta blocker. It is the treatment most consistently shown to relieve the inner restlessness of akathisia, so this is the right choice.
3. Methylphenidate: A stimulant drug. Since the patient is already agitated and unable to keep still, adding a stimulant would only add fuel to the fire.
4. Trihexyphenidyl: An anticholinergic. It is very useful for acute dystonia and for drug-induced parkinsonism, but it does not treat akathisia reliably, since akathisia is not primarily a cholinergic problem.

The picture of pacing and restlessness starting soon after a high dose of a potent antipsychotic like haloperidol is classic akathisia. Among the four choices, propranolol is the one with proven benefit for this specific side effect.

Let's summarize:

• Akathisia is an extrapyramidal side effect distinct from dystonia and parkinsonism.
• Beta blockers such as propranolol are the preferred treatment for akathisia.
• Anticholinergics like trihexyphenidyl are better suited to dystonia and parkinsonism, not akathisia.

So the correct answer is propranolol.