Hexamethonium

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ImageFile=Hexamethonium.pngImageSize=200px
IUPACName=trimethyl-(6-trimethylammoniohexyl)ammonium
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PubChem=3604
SMILES=C [N+] (C)(C)CCCCCC [N+] (C)(C)C
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Formula=C₁₂H₃₀N₂²⁺
MolarMass=202.38
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Hexamethonium is a ganglionic blocker,cite journal |author=Sonoyama K, Tajima K, Fujiwara R, Kasai T |title=Intravenous infusion of hexamethonium and atropine but not propranolol diminishes apolipoprotein A-IV gene expression in rat ileum |journal=The Journal of nutrition |volume=130 |issue=3 |pages=637–41 |year=2000 |month=March |pmid=10702597 |doi= |url=http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=10702597] a neuronal nAch (N_N) receptor antagonist which acts in autonomic ganglia by binding mostly in or on the N_N receptor, and not the acetylcholine binding site itself. It has no effect on the muscarinic acetylcholine receptors (mAChR) located on target organs of the parasympathetic nervous system, nor the nicotinic acetylcholine receptors at the neuromuscular junction (N_M) that are responsible for skeletal muscle motor response.

Pharmacology

It can act on receptors at pre-ganglionic sites in both the sympathetic and parasympathetic nervous system, which are both regulated (again, only pre-ganglionically) by nicotinic acetylcholine receptors. Postganglionic sympathetic systems are usually regulated by norepinephrine or adrenaline (adrenergic receptors), while parasympathetic systems are still acetylcholine based, but instead rely on muscarinic receptors (some post-ganglionic sympathetic neurons, such as those stimulating sweating, release acetylcholine).

The organ system and adverse effects of ganglion blockers are because both the parasympathetic and sympathetic stimuli are blocked at the preganglionic sites. Side effects include combined sympatholytic (e.g. orthostatic hypotension and sexual dysfunction) and parasympatholytic effects (e.g. constipation, urinary retention, glaucoma, blurry vision, decreased lacrymal secretion, dry mouth (xerostomia) effects.

Uses

It was formerly used to treat disorders of the peripheral nervous system, such as chronic hypertension, which is innervated only by the sympathetic nervous system. The non-specificity of this treatment led to discontinuing its use. [Hardman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 10th edition, 2001, pp 210-211.]

The use of hexamethonium, an unapproved drug, in a normal volunteer during a medical study is believed to have caused her death.cite web |url=http://newsbreaks.infotoday.com/nbreader.asp?ArticleID=17534 |title=Johns Hopkins’ Tragedy: Could Librarians Have Prevented a Death? |format= |work= |accessdate=2008-10-06] cite journal |author=Savulescu J, Spriggs M |title=The hexamethonium asthma study and the death of a normal volunteer in research |journal=Journal of medical ethics |volume=28 |issue=1 |pages=3–4 |year=2002 |month=February |pmid=11834748 |pmc=1733509 |doi= |url=http://jme.bmj.com/cgi/pmidlookup?view=long&pmid=11834748]

References

ee also

* Decamethonium