Pyridostigmine

Overview

Pyridostigmine is a medication used to treat myasthenia gravis and underactive bladder. It is also used together with atropine to end the effects of neuromuscular blocking medication of the non-depolarizing type. It is also used off-label to treat some forms of Postural orthostatic tachycardia syndrome.[1–4] WP

It is typically given by mouth but can also be used by injection. When administered orally the effects generally begin within 15–30 minutes and last up to 4 hours.[3] WP

Common side effects include nausea, diarrhea, frequent urination, sweating, and abdominal pain. More severe side effects include low blood pressure, weakness, and allergic reactions. It is unclear if use in pregnancy is safe for the fetus. Pyridostigmine is an acetylcholinesterase inhibitor in the cholinergic family of medications. It works by blocking the action of acetylcholinesterase and therefore increases the levels of acetylcholine.[3] WP

Pyridostigmine was patented in 1945 and came into medical use in 1955. It is on the World Health Organization's List of Essential Medicines. Pyridostigmine is available as a generic medication.[3][5][6][7] WP

Drug class

Acetylcholinesterase inhibitor Parasympathomimetic WP

From the Wikipedia article's infobox.

Uses, dosage and effects

Medical uses

Pyridostigmine is used to treat muscle weakness in people with myasthenia gravis or forms of congenital myasthenic syndrome and to combat the effects of curariform 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 agent Soman in order to increase survival. Used in particular during the first Gulf War, pyridostigmine bromide has been implicated as a causal factor in Gulf War syndrome.[8][9] WP

With pyridostigmine classified as a type of parasympathomimetic, it can be used to treat underactive bladder.[2] WP

Pyridostigmine sometimes is used to treat orthostatic hypotension. It may also be of benefit in chronic axonal polyneuropathy.[10][11] WP

It is also being prescribed off-label for postural orthostatic tachycardia syndrome (POTS) as well as complications resulting from Ehlers–Danlos syndrome.[11][12] WP

Risks and side effects

Contraindications

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] WP

Side effects

Common side effects include:[13] WP

• Sweating[13] WP
• Diarrhea[13] WP
• Nausea[13] WP
• Vomiting[13] WP
• Abdominal cramps[13] WP
• Increased salivation[13] WP
• Tearing[13] WP
• Increased bronchial secretions[13] WP
• Constricted pupils[13] WP
• Facial flushing due to vasodilation[13] WP
• Erectile dysfunction[13] WP

Additional side effects include:[13] WP

• Muscle twitching[13] WP
• Muscle cramps and weakness[13] WP

Pharmacology

Mechanism of action

Pyridostigmine is an acetylcholinesterase inhibitor. It inhibits acetylcholinesterase in the synaptic cleft, thus slowing down the hydrolysis of acetylcholine. Like its predecessor neostigmine, it is a quaternary carbamate inhibitor of cholinesterase that does not cross the blood–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. WP

The ACh diffuses across the synaptic cleft and binds to receptors on the post synaptic membrane, causing an influx of sodium (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 called acetylcholinesterase is present in the endplate membrane close to the receptors on the post synaptic membrane, and quickly hydrolyses ACh. WP

Chemistry

Formula

C9H13N2O2+ PC

Formula (Wikipedia infobox)

C9H13N2O2 WP⚠ Wikipedia and PubChem give different formulas. Both are shown as each source has it.

Note

⚠ The PubChem record carries a charge, so it may describe an ion or salt of this substance rather than the substance itself.

CAS number

155-97-5 PC

Molar mass (g/mol)

181.21 PC

IUPAC name (computed by PubChem)

(1-methylpyridin-1-ium-3-yl) N,N-dimethylcarbamate PC

SMILES

C[N+]1=CC=CC(=C1)OC(=O)N(C)C PC

InChIKey

RVOLLAQWKVFTGE-UHFFFAOYSA-N PC

PubChem CID

4991

Harm reduction information

No harm reduction data is on file for this compound yet. That means no dose, timing or combination data from PsychonautWiki or TripSit. Please don't guess a dose from similar compounds. If you have taken it and feel unwell, contact emergency services or a poison control center.

User reports

Pop culture

No references added yet.

Sources

1. Other WHO Model Formulary 2008. 2009
2. Journal / agency Moro C, Phelps C, Veer V, Clark J, Glasziou P, Tikkinen KA, Scott AM. The effectiveness of parasympathomimetics for treating underactive bladder: A systematic review and meta-analysis. Neurourology and Urodynamics. November 2021. doi:10.1002/nau.24839 · PMID 34816481
3. Other Pyridostigmine Monograph for Professionals
4. Journal / agency Schlömer E, Stein E, Kedor C, Rust R, Brock A, Wittke K, Scheibenbogen C, Kim L. Pyridostigmine improves hand grip strength in patients with myalgic encephalomyelitis/chronic fatigue syndrome. Frontiers in Neuroscience. September 2, 2025. doi:10.3389/fnins.2025.1637838 · PMID 40970182 · PMC12441162
5. Other Fischer J, Ganellin CR. Analogue-based Drug Discovery. 2006
6. Other World Health Organization. World Health Organization model list of essential medicines: 21st list 2019. 2019
7. Journal / agency Competitive Generic Therapy Approvals. 3 March 2023
8. Journal / agency Golomb BA. Acetylcholinesterase inhibitors and Gulf War illnesses. Proceedings of the National Academy of Sciences of the United States of America. March 2008. doi:10.1073/pnas.0711986105 · PMID 18332428 · PMC2393741
9. Other Steenhuysen J. Gulf War illness linked to chemical exposure-study. March 10, 2008
10. Journal / agency Gales BJ, Gales MA. Pyridostigmine in the treatment of orthostatic intolerance. The Annals of Pharmacotherapy. February 2007. doi:10.1345/aph.1H458 · PMID 17284509
11. Journal / agency Galassi G, Canali E, Ariatti A, Valzania F. Concurrent chronic motor axonal polyneuropathy and synaptic impairment of neuromuscular junction. Clinical Neuropharmacology. 2011. doi:10.1097/CND.0b013e3181df2b18 · PMID 22361520
12. Journal / agency Kanjwal K, Karabin B, Sheikh M, Elmer L, Kanjwal Y, Saeed B, Grubb BP. Pyridostigmine in the treatment of postural orthostatic tachycardia: a single-center experience. Pacing and Clinical Electrophysiology. June 2011. doi:10.1111/j.1540-8159.2011.03047.x · PMID 21410722
13. Other Mestinon | Home. link 2
14. Other Mestinon Official FDA information, side effects and uses. link 2

Text and values on this page are quoted from Wikipedia (CC BY-SA 4.0), PubChem (public domain). Each value links to the exact revision it came from.