Drug interactions
Dexamethasone-neomycin-polymyxin + Fosphenytoin
Severity: Moderate
Dexamethasone-neomycin-polymyxin and Fosphenytoin: 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
Phenytoin, the active form of fosphenytoin, induces CYP3A4 and may lower dexamethasone exposure, reducing its effect. Dexamethasone can also alter phenytoin concentrations unpredictably.
What this interaction means in plain words
Dexamethasone-neomycin-polymyxin and Fosphenytoin 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.
Dexamethasone-neomycin-polymyxin belongs to Anti Bacterial; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing dexamethasone clearance.
What to do
Monitor clinical response to dexamethasone and increase the dose if needed. Monitor phenytoin levels when starting or stopping dexamethasone.
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 Dexamethasone-neomycin-polymyxin
- Dexamethasone-neomycin-polymyxin + Ketorolac Major
- Dexamethasone-neomycin-polymyxin + Lapatinib Major
- Dexamethasone-neomycin-polymyxin + Levofloxacin Major
- Dexamethasone-neomycin-polymyxin + Mifepristone Major
- Dexamethasone-neomycin-polymyxin + Moxifloxacin Major
- Aldesleukin + Dexamethasone-neomycin-polymyxin Moderate
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Dexamethasone-neomycin-polymyxin with Fosphenytoin?
MediHelp rates the interaction as moderate. Dexamethasone-neomycin-polymyxin and Fosphenytoin 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. Phenytoin, the active form of fosphenytoin, induces CYP3A4 and may lower dexamethasone exposure, reducing its effect. Dexamethasone can also alter phenytoin concentrations unpredictably.
How serious is the interaction between Dexamethasone-neomycin-polymyxin and Fosphenytoin?
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 clinical response to dexamethasone and increase the dose if needed. Monitor phenytoin levels when starting or stopping dexamethasone.
What other medicines interact with Dexamethasone-neomycin-polymyxin?
MediHelp also lists interactions of Dexamethasone-neomycin-polymyxin with, for example, Ketorolac, Lapatinib, Levofloxacin. The full list is on the Dexamethasone-neomycin-polymyxin page.
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