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Neostigmine

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Neostigmine
File:Neostigmine Ion V.1.svg
File:Neostigmine ball-and-stick.png
Systematic (IUPAC) name
3-{[(dimethylamino)carbonyl]oxy}-N,N,N-trimethylbenzenaminium
Clinical data
Trade names Prostigmin
AHFS/Drugs.com monograph
Pharmacokinetic data
Bioavailability Unclear, probably less than 5%
Metabolism Slow hydrolysis by acetylcholinesterase and also by plasma esterases
Half-life 50–90 minutes
Excretion Unchanged drug (up to 70%) and alcoholic metabolite (30%) are excreted in the urine
Identifiers
59-99-4 7pxY
N07AA01 S01EB06 QA03AB93
PubChem CID 4456
DrugBank DB01400 7pxY
ChemSpider 4301 7pxY
UNII 3982TWQ96G 7pxY
KEGG D08261 7pxY
ChEBI CHEBI:7514 7pxY
ChEMBL CHEMBL54126 7pxN
Chemical data
Formula C12H19N2O2
223.294 g/mol
 14pxN (what is this?)  (verify)

Neostigmine (Prostigmin, Vagostigmin) is a parasympathomimetic that acts as a reversible acetylcholinesterase inhibitor.

Synthesis

Neostigmine was first synthesized by Aeschlimann and Reinert in 1931.[1]

Neostigmine is made by first reacting 3-dimethylaminophenol with N-dimethylcarbamoyl chloride, which forms a dimethylcarbamate. Next, that product is alkylated using dimethylsulfate, which forms neostigmine.[2]

Pharmacology

By interfering with the breakdown of acetylcholine, neostigmine indirectly stimulates both nicotinic and muscarinic receptors. Unlike physostigmine, neostigmine has a quaternary nitrogen; hence, it is more polar and does not enter the CNS, but it does cross the placenta. Its effect on skeletal muscle is greater than that of physostigmine. Neostigmine has moderate duration of action, usually two to four hours.[3] Neostigmine binds to the anionic and esteric site of cholinesterase. The drug blocks the active site of acetylcholinesterase so the enzyme can no longer break down the acetylcholine molecules before they reach the postsynaptic membrane receptors. This allows for the threshold to be reached so a new impulse can be triggered in the next neuron. In myasthenia gravis there are too few acetylcholine receptors so with the acetylcholinesterase blocked, acetylcholine can bind to the few receptors and trigger a muscular contraction.

Clinical uses

It is used to improve muscle tone in people with myasthenia gravis and routinely in anesthesia to reverse the effects of non-depolarizing muscle relaxants such as rocuronium and vecuronium at the end of an operation, usually in a dose of 25 to 50 μg per kilogram.

It can also be used for urinary retention resulting from general anesthesia and to treat curariform drug toxicity.

Another indication for use is the Ogilvie syndrome which is a pseudoobstruction of the colon in critically ill patients.

Historically, it has been used as a test for early pregnancy. In a non-pregnant female whose menstrual period is delayed, administration of neostigmine can provoke menstrual bleeding. Modern tests which rely on detecting hCG in urine have rendered this application obsolete.

Sometimes, hospitals use an intravenous version of neostigmine to delay the effects of envenomation through snakebite.[4]

Though it is one of only two treatments available for myasthenia gravis, this drug is no longer available in the United States to anyone using the Medicare Part D program.

Side effects

Neostigmine can induce generic ocular side effects including: headache, brow pain, blurred vision, phacodonesis, pericorneal injection, congestive iritis, various allergic reactions, and rarely, retinal detachment.[5]

Neostigmine will cause slowing of the heart rate (bradycardia); for this reason it is usually given along with a parasympatholytic drug such as atropine or glycopyrrolate.

Gastrointestial symptoms occur earliest after ingestion and include anorexia, nausea, vomiting, abdominal cramps, and diarrhea.[6]

Spectral data

Neostigmine shows notable UV/VIS absorption at 261 nm, 267 nm, and 225 nm.[7]

Neostigmine's 1H NMR Spectroscopy reveals shifts at: 7.8, 7.7, 7.4, 7.4, 3.8, and 3.1 parts per million. The higher shifts are due to the aromatic hydrogens. The lower shifts at 3.8ppm and 3.1ppm are due to the electronic withdrawing nature of the tertiary and quarterary nitrogen, respectively.[8]

Chemistry

Neostigmine, N,N,N-trimethyl-meta-(dimethylcarbomoyloxy)-phenylammonium methylsulfonate, which can be viewed as a simplified analog of physostigmine, is made by reacting 3-dimethylaminophenol with N-dimethylcarbamoyl chloride, which forms the dimethylcarbamate, and its subsequent alkylation using dimethylsulfate forming the desired compound. 800px

See also

References

  1. ^ Whitacre 2007, pp. 57.
  2. ^ Gilman, Goodman & Gilman 1980, pp. 103.
  3. ^ Howland, R. D., Mycek, M. J., Harvey, R. A., Champe, P. C., & Mycek, M. J. Pharmacology 3rd edition, Lippincott's Illustrated Reviews, 2008, pg. 51.
  4. ^ Potential Treatment For Snakebites Leads To A Paralyzing Test : Shots - Health News : NPR
  5. ^ Gilman, Goodman & Gilman 1980, pp. 114.
  6. ^ Gilman, Goodman & Gilman 1980, pp. 109.
  7. ^ Porst H; Kny L (May 1985). "[The structure of degradation products of neostigmine bromide]". Pharmazie. (in German) 40 (5): 325–8. PMID 4034636. 
  8. ^ Ferdous, Abu J; Waigh, Roger D (1993). "Application of the WATR technique for water suppression in 1H NMR spectroscopy in determination of the kinetics of hydrolysis of neostigmine bromide in aqueous solution". Journal of Pharmacy and Pharmacology 45 (6): 559–562. PMID 8103105. doi:10.1111/j.2042-7158.1993.tb05598.x. 

Bibliography

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