Drug interactions
Fosphenytoin + Tinidazole
Severity: Moderate
Fosphenytoin and Tinidazole: 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 can lower tinidazole concentrations. Nitroimidazoles such as metronidazole have been reported to raise phenytoin levels, so toxicity of phenytoin is also possible.
What this interaction means in plain words
Fosphenytoin and Tinidazole 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.
Fosphenytoin belongs to Central Nervous System; Tinidazole belongs to Anti Parasitic.
Why it happens
Phenytoin induces CYP3A4 and increases tinidazole clearance, while nitroimidazoles may inhibit phenytoin metabolism.
What to do
Monitor phenytoin levels and for signs of toxicity such as nystagmus and ataxia, and assess clinical response to tinidazole.
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 Tinidazole
- Disulfiram + Tinidazole Contraindicated
- Ethanol + Tinidazole Major
- Fexinidazole + Tinidazole Major
- Lopinavir + Tinidazole Major
- Nilotinib + Tinidazole Major
- Ritonavir + Tinidazole Major
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 Fosphenytoin with Tinidazole?
MediHelp rates the interaction as moderate. Fosphenytoin and Tinidazole 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 can lower tinidazole concentrations. Nitroimidazoles such as metronidazole have been reported to raise phenytoin levels, so toxicity of phenytoin is also possible.
How serious is the interaction between Fosphenytoin and Tinidazole?
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 phenytoin levels and for signs of toxicity such as nystagmus and ataxia, and assess clinical response to tinidazole.
What other medicines interact with Tinidazole?
MediHelp also lists interactions of Tinidazole with, for example, Disulfiram, Ethanol, Fexinidazole. The full list is on the Tinidazole page.
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