Drug interactions
Cyclobenzaprine + Physostigmine
Severity: Major
Cyclobenzaprine and Physostigmine: major 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
Physostigmine inhibits acetylcholinesterase and can reverse central and peripheral anticholinergic toxicity, which is why it is used in anticholinergic overdose. Cyclobenzaprine's antimuscarinic effects therefore oppose physostigmine, and in tricyclic-type overdose physostigmine can provoke seizures and arrhythmias.
What this interaction means in plain words
Cyclobenzaprine and Physostigmine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Pharmacodynamic antagonism between a cholinesterase inhibitor and an antimuscarinic agent, with added proconvulsant and cardiac risk in overdose.
What to do
Avoid physostigmine in cyclobenzaprine overdose with QRS widening or seizure risk; if used, give slowly with continuous ECG monitoring and resuscitation equipment available.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Cyclobenzaprine
- Cyclobenzaprine + Isocarboxazid Contraindicated
- Cyclobenzaprine + Linezolid Contraindicated
- Cyclobenzaprine + Phenelzine Contraindicated
- Cyclobenzaprine + Safinamide Contraindicated
- Cyclobenzaprine + Selegiline Contraindicated
- Cyclobenzaprine + Selegiline transdermal Contraindicated
Frequently asked questions
Can I take Cyclobenzaprine with Physostigmine?
MediHelp rates the interaction as major. Cyclobenzaprine and Physostigmine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Physostigmine inhibits acetylcholinesterase and can reverse central and peripheral anticholinergic toxicity, which is why it is used in anticholinergic overdose. Cyclobenzaprine's antimuscarinic effects therefore oppose physostigmine, and in tricyclic-type overdose physostigmine can provoke seizures and arrhythmias.
How serious is the interaction between Cyclobenzaprine and Physostigmine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid physostigmine in cyclobenzaprine overdose with QRS widening or seizure risk; if used, give slowly with continuous ECG monitoring and resuscitation equipment available.
What other medicines interact with Cyclobenzaprine?
MediHelp also lists interactions of Cyclobenzaprine with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Cyclobenzaprine page.
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