Drug interactions
Pefloxacin + Tizanidine
Severity: Contraindicated
Pefloxacin and Tizanidine: contraindicated 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
Pefloxacin inhibits CYP1A2, the main enzyme clearing tizanidine, so tizanidine levels can rise markedly. This can cause severe hypotension, bradycardia and profound sedation, as seen with the related drug ciprofloxacin.
What this interaction means in plain words
Pefloxacin and Tizanidine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Pefloxacin belongs to Anti Bacterial; Tizanidine belongs to Musculoskeletal.
Why it happens
Inhibition of CYP1A2 by pefloxacin reduces tizanidine clearance.
What to do
Avoid the combination and use an antibiotic that does not inhibit CYP1A2. If it cannot be avoided, use a much lower tizanidine dose and monitor blood pressure and heart rate closely.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Tizanidine
- Ciprofloxacin + Tizanidine Contraindicated
- Fluvoxamine + Tizanidine Contraindicated
- Pipemidic acid + Tizanidine Contraindicated
- Benzhydrocodone / acetaminophen + Tizanidine Major
- Brexanolone + Tizanidine Major
- Buprenorphine long-acting + Tizanidine Major
Other interactions of Pefloxacin
- Clozapine + Pefloxacin Major
- Duloxetine + Pefloxacin Major
- Pefloxacin + Theophylline Major
- Asenapine + Pefloxacin Moderate
- Caffeine + Pefloxacin Moderate
- Cimetidine + Pefloxacin Moderate
Frequently asked questions
Can I take Pefloxacin with Tizanidine?
MediHelp rates the interaction as contraindicated. Pefloxacin and Tizanidine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Pefloxacin inhibits CYP1A2, the main enzyme clearing tizanidine, so tizanidine levels can rise markedly. This can cause severe hypotension, bradycardia and profound sedation, as seen with the related drug ciprofloxacin.
How serious is the interaction between Pefloxacin and Tizanidine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and use an antibiotic that does not inhibit CYP1A2. If it cannot be avoided, use a much lower tizanidine dose and monitor blood pressure and heart rate closely.
What other medicines interact with Tizanidine?
MediHelp also lists interactions of Tizanidine with, for example, Ciprofloxacin, Fluvoxamine, Pipemidic acid. The full list is on the Tizanidine page.
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