A 19-year-old woman receives a single intravenous dose of metoclopramide before endoscopy. Two hours later she develops torticollis, trismus, and upward deviation of both eyes. Which drug should be administered immediately?

• A Propranolol
• B Promethazine
• C Haloperidol
• D Benztropine ✓

Explanation

Metoclopramide is a central dopamine C2 antagonist, and acute dystonic reactions such as oculogyric crisis and torticollis occur especially in young patients, females, and after high doses. Because the reaction reflects relative striatal cholinergic excess from dopaminergic blockade, it is reversed promptly by an anticholinergic such as benztropine or by promethazine, which itself carries anticholinergic properties. Giving haloperidol would worsen dystonia, and propranolol treats akathisia rather than dystonia.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th ed.

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Written and medically reviewed by the StethoPrep medical team.