Drug interactions
Amantadine + Sulfamethoxazole
Severity: Moderate
Amantadine and Sulfamethoxazole: 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
The interaction is attributed mainly to the trimethoprim component, which can reduce renal tubular secretion of amantadine. Higher amantadine concentrations may cause confusion, hallucinations, myoclonus or seizures, particularly in older patients or those with renal impairment.
What this interaction means in plain words
Amantadine and Sulfamethoxazole 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
Competition for renal tubular cation secretion, reducing amantadine clearance.
What to do
Monitor for amantadine toxicity such as confusion, myoclonus and hallucinations; reduce the amantadine dose in renal impairment or choose an alternative antibiotic.
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 Amantadine
- Amantadine + Ethanol Major
- Amantadine + Memantine-donepezil Major
- Amantadine + Metoclopramide Major
- Amantadine + Metoclopramide intranasal Major
- Amantadine + Amifampridine Moderate
- Amantadine + Amisulpride Moderate
Frequently asked questions
Can I take Amantadine with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Amantadine and Sulfamethoxazole 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. The interaction is attributed mainly to the trimethoprim component, which can reduce renal tubular secretion of amantadine. Higher amantadine concentrations may cause confusion, hallucinations, myoclonus or seizures, particularly in older patients or those with renal impairment.
How serious is the interaction between Amantadine and Sulfamethoxazole?
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 for amantadine toxicity such as confusion, myoclonus and hallucinations; reduce the amantadine dose in renal impairment or choose an alternative antibiotic.
What other medicines interact with Amantadine?
MediHelp also lists interactions of Amantadine with, for example, Ethanol, Memantine-donepezil, Metoclopramide. The full list is on the Amantadine page.
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