The most important drugs producing extrapyramidal and motor side effects

1. Big picture

Extrapyramidal and motor side effects are abnormal movements or abnormal muscle tone caused by drugs that disturb basal ganglia, dopamine, serotonin, cerebellar, or neuromuscular function.

The most important drug group is:

Dopamine receptor blockers, especially neuroleptics and antiemetics.

The key exam sentence:

The most important drugs producing extrapyramidal side effects are neuroleptics such as haloperidol, chlorpromazine and levomepromazine, and dopamine-blocking antiemetics such as metoclopramide, thiethylperazine, sulpiride and domperidone.

The most important exam trap:

A patient with new dystonia, parkinsonism, akathisia or tardive dyskinesia may not have a primary neurological disease — it may be a drug side effect.

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2. What are extrapyramidal side effects?

Extrapyramidal side effects are drug-induced movement disorders caused mainly by disturbance of the basal ganglia motor circuits.

Main forms:

• acute dystonia;
• drug-induced parkinsonism;
• akathisia;
• tardive dyskinesia;
• tardive dystonia;
• tardive akathisia;
• tremor;
• chorea-like movements;
• restless legs syndrome;
• myoclonus;
• neuroleptic malignant syndrome.

The mechanism is often:

dopamine blockade or dopamine depletion in the nigrostriatal pathway.

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3. Main drug groups causing extrapyramidal and motor side effects

NMS = neuroleptic malignant syndrome. SSRI = selective serotonin reuptake inhibitor. RLS = restless legs syndrome.

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4. Dopamine-blocking drugs: the most important cause