Drug interactions
Isoniazid + Levodopa inhaled
Severity: Moderate
Isoniazid and Levodopa inhaled: moderate 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
Isoniazid may reduce the benefit of levodopa, and inhaled levodopa is expected to behave like oral levodopa in this respect. Loss of motor control or, in some reports, hypotension and flushing have occurred with the oral combination. Evidence is limited.
What this interaction means in plain words
Isoniazid and Levodopa inhaled can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Isoniazid may inhibit dopa-decarboxylase (it is a pyridoxal phosphate antagonist), which could impair conversion of levodopa to dopamine; the effect is not firmly established.
What to do
Monitor Parkinson's disease symptom control and blood pressure when starting or stopping isoniazid. Adjust the levodopa regimen if motor fluctuations worsen.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Levodopa inhaled?
MediHelp rates the interaction as moderate. Isoniazid and Levodopa inhaled can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Isoniazid may reduce the benefit of levodopa, and inhaled levodopa is expected to behave like oral levodopa in this respect. Loss of motor control or, in some reports, hypotension and flushing have occurred with the oral combination. Evidence is limited.
How serious is the interaction between Isoniazid and Levodopa inhaled?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor Parkinson's disease symptom control and blood pressure when starting or stopping isoniazid. Adjust the levodopa regimen if motor fluctuations worsen.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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