Drug interactions
Carbidopa-levodopa + Metyrosine
Severity: Major
Carbidopa-levodopa and Metyrosine: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Metyrosine inhibits tyrosine hydroxylase and depletes catecholamines, while levodopa supplies dopamine by bypassing that step. The two have opposing actions: metyrosine may blunt the effect of levodopa and can cause parkinsonism-like extrapyramidal effects. Hypotension is also possible.
What this interaction means in plain words
Carbidopa-levodopa and Metyrosine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Carbidopa-levodopa belongs to Central Nervous System; Metyrosine belongs to Miscellaneous.
Why it happens
Metyrosine blocks tyrosine hydroxylase, reducing catecholamine synthesis, which opposes the dopaminergic effect of levodopa.
What to do
Avoid the combination where possible. If both are needed, monitor motor symptoms and blood pressure closely and adjust doses.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Carbidopa-levodopa
- Carbidopa-levodopa + Isocarboxazid Contraindicated
- Carbidopa-levodopa + Phenelzine Contraindicated
- Carbidopa-levodopa + Selegiline transdermal Contraindicated
- Carbidopa-levodopa + Tranylcypromine Contraindicated
- Amisulpride + Carbidopa-levodopa Major
- Asenapine + Carbidopa-levodopa Major
Other interactions of Metyrosine
- Fluphenazine + Metyrosine Major
- Metoclopramide + Metyrosine Major
- Carbidopa-entacapone-levodopa + Metyrosine Moderate
- Chlorpromazine + Metyrosine Moderate
- Clonidine + Metyrosine Moderate
- Haloperidol + Metyrosine Moderate
Frequently asked questions
Can I take Carbidopa-levodopa with Metyrosine?
MediHelp rates the interaction as major. Carbidopa-levodopa and Metyrosine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Metyrosine inhibits tyrosine hydroxylase and depletes catecholamines, while levodopa supplies dopamine by bypassing that step. The two have opposing actions: metyrosine may blunt the effect of levodopa and can cause parkinsonism-like extrapyramidal effects. Hypotension is also possible.
How serious is the interaction between Carbidopa-levodopa and Metyrosine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible. If both are needed, monitor motor symptoms and blood pressure closely and adjust doses.
What other medicines interact with Carbidopa-levodopa?
MediHelp also lists interactions of Carbidopa-levodopa with, for example, Isocarboxazid, Phenelzine, Selegiline transdermal. The full list is on the Carbidopa-levodopa page.
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