Drug of the week series 14 - 3

Scenario:
A 72-year-old man with Parkinson’s disease develops nausea after surgery. The resident suggests prescribing metoclopramide, but the senior physician advises against it.

Why is metoclopramide generally avoided in patients with Parkinson’s disease?
  • It increases blood glucose levels.
  • It worsens Parkinsonian symptoms by blocking dopamine receptors.
  • It causes severe hypertension.
  • It reduces the effectiveness of antibiotics.
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Question

Can you explain the pharmacological reason why metoclopramide is contraindicated in Parkinson’s disease?

MBH/PS

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In Parkinson’s there is deficiency of dopamine

Metoclopramide is dopamine receptor antagonist so using this in Parkinson’s causes worsening of symptoms so we should avoid it

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As Parkinson patients have depleted dopamine level and metoclopramide works as a dopamine receptor antagonist, so administering the medicine would worsen symptoms.

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It is avoided because it blocks D2 receptor. And in Parkinson disease already deficiency of dopamine is there… metoclopramide is blocking that receptor only that’s why it is contraindicated.

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Metoclopramide is contraindicated in Parkinson’s disease because it is a central D₂ receptor antagonist that further reduces dopaminergic activity in the nigrostriatal pathway, worsening Parkinsonian symptoms and increasing the risk of extrapyramidal adverse effects.

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Metoclopramide works by blocking dopamine and serotonin receptors in the brain and by increasing muscle contractions in the upper digestive tract to increase the rate of stomach emptying. It causes uncontrolled movement of muscles, which can worsen the symptoms of Parkinsons. So it is better to avoid and go for a safe non-dopaminergic alternative like ondansetron.

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Metoclopramide is contradicted in parkinson because it blocks the centralized D2 Dopamine receptors, since it worsens the condition that is why it is contradicted

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Metoclopramide is a D2 receptor antagonist, when given in patients with Parkinson’s disease it even worsens the case, as in patients with Parkinsonism already low dopamine activity.

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Parkinson’s disease, there is already a deficiency of dopamine in the brain. Metoclopramide crosses the blood-brain barrier and further blocks dopamine receptors, which can:
Worsen Parkinson’s symptoms such as tremor, rigidity, and slowness of movement (bradykinesia

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Metoclopramide is contraindicated in Parkinson’s disease because it blocks dopamine receptors and in Parkinson’s, dopamine levels are already low, so it can worsen the condition.

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In Parkinson’s disease already dopamine levels is depleted and metoclopramide acts as an dopamine D2 receptor antagonist which worsen the symptoms.

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Parkinson disease occur due to deficiency of dopamine, Metoclopramide is Dopamine receptor antagonist, it would exaggerate Parkinson so we should avoid it

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Metoclopramide is a dopamine antagonist,so it works by blocking dopamine receptors. In Parkinson’s Disease, There’s already a shortage of dopamine, so blocking those receptors should make the symptoms much worse.

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