Nicotinic antagonist

{{short description|Drug that inhibits the action of acetylcholine at nicotinic acetylcholine receptors}} A '''nicotinic antagonist''' is a type of anticholinergic drug that inhibits the action of acetylcholine (ACh) at nicotinic acetylcholine receptors. These compounds are mainly used for peripheral muscle paralysis in surgery, the classical agent of this type being tubocurarine,<ref>P. Taylor (1990). In ''Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th Ed.'', (A. G. Gilman et al., Eds.), pp. 166-186, New York: Pergamon Press.</ref> but some centrally acting compounds such as bupropion, mecamylamine, and 18-methoxycoronaridine block nicotinic acetylcholine receptors in the brain and have been proposed for treating nicotine addiction.{{medical citation needed|date=May 2012}}

{|class="wikitable" |+Comparison |- !Mechanism !Antagonist !Preferred receptor !Clinical use |- !rowspan=3|Ganglionic blocking agents |Hexamethonium | Ganglion type | None<ref name=Rang149>{{cite book |author=Rang, H. P. |title=Pharmacology |publisher=Churchill Livingstone |location=Edinburgh |year=2003 |isbn=0-443-07145-4 }} Page 149</ref> |- |Mecamylamine | Ganglion type | |- |Trimethaphan | Ganglion type | Rarely used for blood pressure decrease during surgery<ref name=Rang149/> |- !rowspan=6| Nondepolarizing neuromuscular blocking agents |Atracurium | Muscle type | Muscle relaxant in anaesthesia<ref name=Rang149/> |- |Doxacurium | Muscle type | |- |Mivacurium | Muscle type | |- |Pancuronium | Muscle type | Muscle relaxant in anaesthesia<ref name=Rang149/> |- |Tubocurarine | Muscle type | Discovered in arrow poison; it was the first peripheral muscle relaxant. Rarely used since the 1980s.<ref name=Rang149/> |- |Vecuronium | Muscle type | Muscle relaxant in anaesthesia<ref name=Rang149/> |- !rowspan=1| Depolarizing neuromuscular blocking agents |Succinylcholine* | Muscle type | |- !rowspan=7| Centrally acting nicotinic antagonists |18-Methoxycoronaridine | α3β4 | |- |Bupropion | α3β4. α4β2, α1β1γδ | Antidepressant (NDRI) | |- |Hydroxybupropion | α3β4. α4β2, α1β1γδ | Antidepressant (NDRI). Metabolite of bupropion. | |- |Threohydrobupropion | α3β4. | Antidepressant (NDRI). Metabolite of bupropion. | |- |Dextromethorphan | α3β4. α4β2, α7 | Common over the counter antitussive. |- |Dextrorphan | α3β4. α4β2, α7 | Metabolite of dextromethorphan; no accepted medical uses. |- |3-Methoxymorphinan | α3β4 | Secondary metabolite of dextromethorphan; not used in medical practice. Unknown medical efficacy. |- |}

*Note: Succinylcholine is a nicotinic agonist. See neuromuscular blocking agents page for details on the mechanism of action.

== References == {{Reflist|2}}

==External links== *{{Commonscatinline|Nicotinic antagonists}} *{{MeshName|Nicotinic+antagonists}}

{{Pharmacomodulation}} {{Navboxes | title = Medical uses | titlestyle = background:#ccccff | list1 = {{Dependence treatment}} {{Antihypertensives and diuretics}} {{Muscle relaxants}} }} {{Acetylcholine receptor modulators}}

Category:Nicotinic antagonists