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| Trade names | Mestinon, others |
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a682229 |
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| Routes of administration | By mouth,intravenous |
| Drug class | Acetylcholinesterase inhibitor;Parasympathomimetic |
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| Pharmacokinetic data | |
| Bioavailability | 7.6 ± 2.4% |
| Eliminationhalf-life | 1.78 ± 0.24 hours |
| Excretion | kidney |
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| Chemical and physical data | |
| Formula | C9H13N2O2 |
| Molar mass | 181.215 g·mol−1 |
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Pyridostigmine is a medication used to treatmyasthenia gravis[1] and underactive bladder.[2] It is also used together withatropine to end the effects ofneuromuscular blocking medication of thenon-depolarizing type.[3] It is also used off-label to treat some forms ofPostural orthostatic tachycardia syndrome. It is typically givenby mouth but can also be used by injection.[3] The effects generally begin within 45 minutes and last up to 4 hours.[3]
Common side effects include nausea, diarrhea, frequent urination, sweating, and abdominal pain.[3] More severe side effects includelow blood pressure, weakness, andallergic reactions.[3] It is unclear if use inpregnancy is safe for the fetus.[3] Pyridostigmine is anacetylcholinesterase inhibitor in thecholinergic family of medications.[3] It works by blocking the action ofacetylcholinesterase and therefore increases the levels ofacetylcholine.[3]
Pyridostigmine was patented in 1945 and came into medical use in 1955.[4] It is on theWorld Health Organization's List of Essential Medicines.[5] Pyridostigmine is available as ageneric medication.[3][6]
Pyridostigmine is used to treat muscle weakness in people withmyasthenia gravis or forms ofcongenital myasthenic syndrome and to combat the effects ofcurariform drug toxicity. Pyridostigmine bromide has been FDA approved for military use during combat situations as an agent to be given prior to exposure to the nerve agentSoman in order to increase survival. Used in particular during the firstGulf War, pyridostigmine bromide has been implicated as a causal factor inGulf War syndrome.[7][8]
With pyridostigmine classified as a type ofparasympathomimetic, it can be used to treat underactive bladder.[9]
Pyridostigmine sometimes is used to treatorthostatic hypotension.[10] It may also be of benefit in chronic axonalpolyneuropathy.[11]
It is also being prescribedoff-label forpostural orthostatic tachycardia syndrome (POTS) as well as complications resulting fromEhlers–Danlos syndrome.[11][12]
Pyridostigmine bromide is contraindicated in cases of mechanical intestinal or urinary obstruction and should be used with caution in patients with bronchial asthma.[13][14]
Common side effects include:[13]
Additional side effects include:[13]
Pyridostigmine is anacetylcholinesterase inhibitor. Itinhibitsacetylcholinesterase in thesynaptic cleft, thus slowing down thehydrolysis ofacetylcholine. Like its predecessorneostigmine, it is a quaternarycarbamate inhibitor of cholinesterase that does not cross theblood–brain barrier. It carbamylates about 30% of peripheral cholinesterase enzyme, and the carbamylated enzyme eventually regenerates by natural hydrolysis and excess acetylcholine (ACh) levels revert to normal.
The ACh diffuses across the synaptic cleft and binds to receptors on the post synaptic membrane, causing an influx ofsodium (Na+,) resulting in depolarization. If large enough, this depolarization results in an action potential. To prevent constant stimulation once the ACh is released, an enzyme calledacetylcholinesterase is present in the endplate membrane close to the receptors on the post synaptic membrane, and quickly hydrolyses ACh.
Pyridostigmine bromide is available under the trade name Mestinon (Valeant Pharmaceuticals), Regonol and Gravitor (SUN Pharma).
