Editing Quaternary ammonium cation (section)

===Medicines===

[[file:Butylscopolamine skeletal.svg|right|thumb|220px|[[Buscopan]] is one of many [[Antispasmodic|spasmo&shy;lytics]] (anti-spasm drugs) that feature the quaternary ammonium [[functional group]].<ref>{{Ullmann |doi=10.1002/14356007.a24_515| title=Spasmolytics | year=2000 | vauthors = Bungardt E, Mutschler E | isbn=3527306730}}</ref>]]

Quaternary ammonium compounds have antimicrobial activity.<ref>{{cite journal | vauthors = Jia Z, shen D, Xu W | title = Synthesis and antibacterial activities of quaternary ammonium salt of chitosan | journal = Carbohydrate Research | volume = 333 | issue = 1 | pages = 1–6 | date = June 2001 | pmid = 11423105 | doi = 10.1016/S0008-6215(01)00112-4 }}</ref> Quaternary ammonium compounds, especially those containing long alkyl chains, are used as [[antimicrobial]]s and [[disinfectant]]s. Examples are [[benzalkonium chloride]], [[benzethonium chloride]], methylbenzethonium chloride, [[cetalkonium chloride]], [[cetylpyridinium chloride]], [[cetrimonium]], [[cetrimide]], dofanium chloride, [[tetraethylammonium bromide]], [[didecyldimethylammonium chloride]] and [[domiphen bromide]]. Also good against [[fungi]], [[amoebas]], and [[viral envelope|enveloped]] [[viruses]] (such as [[COVID-19|SARS-CoV-2]]),<ref name=questionable>{{cite web |url=http://www.mansfield.ohio-state.edu/~sabedon/biol2032.htm |title=Specific Antimicrobials | vauthors = Abedon ST |publisher=Ohio State University |access-date=2020-02-14|url-status=dead |archive-url=https://web.archive.org/web/20081015002934/http://www.mansfield.ohio-state.edu/~sabedon/biol2032.htm |archive-date=2008-10-15 }}</ref><ref>{{cite journal | vauthors = Schrank CL, Minbiole KP, Wuest WM | title = Are Quaternary Ammonium Compounds, the Workhorse Disinfectants, Effective against Severe Acute Respiratory Syndrome-Coronavirus-2? | journal = ACS Infectious Diseases | volume = 6 | issue = 7 | pages = 1553–1557 | date = July 2020 | pmc = 7341688 | doi = 10.1021/acs.estlett.0c00437 | pmid = 32412231 }}</ref> most quaternary ammonium compounds are believed to act by disrupting the [[cell membrane]] or [[viral envelope]].<ref>{{cite journal | vauthors = Cocco AR, Rosa WL, Silva AF, Lund RG, Piva E | title = A systematic review about antibacterial monomers used in dental adhesive systems: Current status and further prospects | journal = Dental Materials | volume = 31 | issue = 11 | pages = 1345–1362 | date = November 2015 | pmid = 26345999 | doi = 10.1016/j.dental.2015.08.155 }}</ref> (Some QACs, such as [[dequalinium]] and similar bis-QACs, show evidence of a different mode of action.)<ref name=Tischer>{{cite journal |last1=Tischer |first1=Maximilian |last2=Pradel |first2=Gabriele |last3=Ohlsen |first3=Knut |last4=Holzgrabe |first4=Ulrike |title=Quaternary Ammonium Salts and Their Antimicrobial Potential: Targets or Nonspecific Interactions? |journal=ChemMedChem |date=2 January 2012 |volume=7 |issue=1 |pages=22–31 |doi=10.1002/cmdc.201100404|pmid=22113995 |s2cid=26326417 }}</ref>

Quaternary ammonium compounds are lethal to a wide variety of organisms except [[endospores]] and [[non-enveloped virus]]es, both having no accessible membrane coat to attack. It is possible to solve the endospore problem by adding chemicals which force them to germinate.<ref>{{cite journal |last1=Nerandzic |first1=MM |last2=Donskey |first2=CJ |title=A Quaternary Ammonium Disinfectant Containing Germinants Reduces Clostridium difficile Spores on Surfaces by Inducing Susceptibility to Environmental Stressors. |journal=Open Forum Infectious Diseases |date=October 2016 |volume=3 |issue=4 |pages=ofw196 |doi=10.1093/ofid/ofw196 |pmid=28066792|pmc=5198585 }}</ref><ref>{{cite journal |last1=Tuladhar |first1=E |last2=de Koning |first2=MC |last3=Fundeanu |first3=I |last4=Beumer |first4=R |last5=Duizer |first5=E |title=Different virucidal activities of hyperbranched quaternary ammonium coatings on poliovirus and influenza virus. |journal=Applied and Environmental Microbiology |date=April 2012 |volume=78 |issue=7 |pages=2456–8 |doi=10.1128/AEM.07738-11 |pmid=22287007|pmc=3302582 |bibcode=2012ApEnM..78.2456T }}</ref> They have reduced efficacy against [[gram-negative bacteria]], [[mycobacteria]], and bacteria in [[biofilm]]s due to them having additional layers that need to be penetrated or disrupted. Some bacteria such as MRSA have acquired resistance genes, ''qacA/B'' and ''qacC/D'', that pump the cation out of the cell.<ref name=Tischer/>