Mivacurium and Neostigmine Methylsulfate: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Neostigmine Methylsulfate
Mivacurium
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Delayed recovery from neuromuscular blockade associated with anesthesia
Interaction Deep Dive
In a study of patients undergoing elective surgery, it was found that neostigmine was less effective in antagonizing neuromuscular blockade induced by mivacurium compared with its effectiveness in antagonizing vecuronium-induced blockade1. After neostigmine administration, mivacurium serum concentrations increased due to what was believed to be neostigmine interference with mivacurium metabolism by plasma cholinesterase.
Why it happens (mechanism)
Possible inhibition by neostigmine of mivacurium metabolism
Literature reports
1 report — tap to read
a) Five patients were infused with mivacurium to maintain 90% depression of twitch tension, after which IV neostigmine 50 mcg/kg was given. Infusion of mivacurium was continued unchanged during neostigmine administration. In a similar manner, 5 patients received vecuronium and neostigmine. Antagonism of mivacurium by neostigmine was 39% +/- 11% compared with 54% +/- 9% for vecuronium. Concentrations of mivacurium stereoisomers increased after neostigmine administration. At 2 minutes after the neostigmine infusion began, concentrations of trans-trans and cis-trans isomers of mivacurium increased by 20% and 35%, respectively. Pre-neostigmine and post-neostigmine concentrations of vecuronium did not vary. Neostigmine given with mivacurium apparently decreased the activity of plasma cholinesterase and thereby increased mivacurium serum concentrations 1.
Common questions
Can I take Mivacurium and Neostigmine Methylsulfate together?
Delayed recovery from neuromuscular blockade associated with anesthesia Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mivacurium and Neostigmine Methylsulfate interaction?
It is rated minor. Usually limited clinical impact.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Mivacurium or Neostigmine Methylsulfate need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Szenohradszky J, Lau M, Brown R, et al: The effect of neostigmine on twitch tension and muscle relaxant concentration during infusion of mivacurium or vecuronium. Anesthesiology 1995; 83:83-87. PubMed
Keep reading about Neostigmine Methylsulfate
Keep reading about Mivacurium
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