Which premedication is associated with extrapyramidal side effects?

Which premedication is associated with extrapyramidal side effects?

• A. Metoclopramide
• B. Cimetidine
• C. Scopolamine
• D. Glycopyrrolate

Answer: (A)

Extrapyramidal side effects come from blocking dopamine D2 receptors in the basal ganglia. Metoclopramide, while used as an antiemetic and prokinetic agent, blocks D2 receptors in the CNS, including the nigrostriatal pathway, which can produce acute dystonias, akathisia, parkinsonian symptoms, and even tardive dyskinesia with long-term use. The other drugs listed do not produce this Dopamine-receptor–mediated extrapyramidal risk: cimetidine is an H2 blocker with minimal EPS risk, and scopolamine and glycopyrrolate are antimuscarinics that affect acetylcholine rather than dopamine (and anticholinergics are sometimes used to treat EPS rather than cause it).

Extrapyramidal side effects come from blocking dopamine D2 receptors in the basal ganglia. Metoclopramide, while used as an antiemetic and prokinetic agent, blocks D2 receptors in the CNS, including the nigrostriatal pathway, which can produce acute dystonias, akathisia, parkinsonian symptoms, and even tardive dyskinesia with long-term use. The other drugs listed do not produce this Dopamine-receptor–mediated extrapyramidal risk: cimetidine is an H2 blocker with minimal EPS risk, and scopolamine and glycopyrrolate are antimuscarinics that affect acetylcholine rather than dopamine (and anticholinergics are sometimes used to treat EPS rather than cause it).