Neostigmine
An injected anticholinesterase used to reverse non-depolarizing muscle relaxants after surgery and to treat myasthenia gravis.
Drug card
- Class
- Anticholinesterase
- How it works
- Blocking acetylcholinesterase, so acetylcholine builds up at synapses
- Used for
- Reversing non-depolarizing muscle relaxants after surgery
- Myasthenia gravis
- Urinary retention after surgery
- Known for
- Slow heart rate
- Its name
- -stigmine means a cholinesterase inhibitor
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does neostigmine work?
A reversible, competitive inhibitor of acetylcholinesterase. The acetylcholine that builds up at the neuromuscular junction outcompetes non-depolarizing blockers such as rocuronium and restores muscle power, while its muscarinic effects, bradycardia above all, call for an antimuscarinic alongside. As a quaternary compound it is poorly absorbed by mouth and short acting.
Like other anticholinesterases: They bind reversibly to acetylcholinesterase and block it, so acetylcholine is broken down more slowly and builds up at synapses. At the neuromuscular junction the extra acetylcholine strengthens weak muscles in myasthenia gravis and outcompetes non-depolarizing blockers. It also boosts muscarinic effects on the gut, glands, airways and heart, which cause most side effects.
Uses
What is neostigmine used for?
- Reversing non-depolarizing muscle relaxants after surgery
- Myasthenia gravis
- Urinary retention after surgery
Side effects
Side effects of neostigmine
- Slow heart rateKnown forSerious
- Heart blockSerious
- Arrhythmias and, rarely, cardiac arrestSerious
- Low blood pressure
- Nausea and vomiting
- Excess saliva and bronchial secretions
- BronchospasmSerious
- Abdominal cramps
- Sweating
- Muscle twitching and cramps
- Cholinergic crisis in overdoseSerious
- Allergic reactions, including anaphylaxisSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- An antimuscarinic such as glycopyrrolate or atropine is given before or with it to prevent bradycardia.
- Contraindicated with peritonitis or mechanical obstruction of the gut or urinary tract.
- Heart disease, arrhythmias or recent coronary occlusion: ECG and blood pressure are watched closely.
- It prolongs the block from suxamethonium instead of reversing it.
Good to know: Shorter acting than pyridostigmine and given by injection, mainly to reverse non-depolarizing blockade at the end of surgery.
Remember it
A way to remember it
DUMBBELSS
- D
- Diarrhea
- U
- Urination
- M
- Miosis
- B
- Bradycardia
- B
- Bronchospasm and bronchial secretions
- E
- Emesis (vomiting)
- L
- Lacrimation (watery eyes)
- S
- Salivation
- S
- Sweating
A mnemonic widely used in teaching
Its name
-stigmine means cholinesterase inhibitor
Neostigmine reverses non-depolarizing muscle relaxants and rivastigmine treats dementia. Donepezil, a cholinesterase inhibitor used for dementia, doesn't carry the stem.
- Every drug name stem
Its class
Anticholinesterases
Other anticholinesterases with a card:
Easily mixed up with direct-acting muscarinic agonists and cholinesterase inhibitors for dementia.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Neostigmine methylsulfate injection: label (DailyMed)
- Neostigmine methylsulfate injection: SmPC (emc)
- Neostigmine (NCI Thesaurus)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Autonomic nervous system
Neostigmine is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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