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			{{For|the use of this chemical as a drug|Nitroglycerin (medication)}}
	{{About|the chemical properties of nitroglycerin and its use as an explosive|medical and pharmacological applications|glyceryl trinitrate (pharmacology)}}
			{{short description|Chemical compound}}
	{{Chembox		{{Chembox
	| Verifiedfields = changed		| Watchedfields = changed
			| verifiedrevid = 408765228
	| Watchedfields = changed
			| Name = Nitroglycerin
	| verifiedrevid = 394801541
	| ImageFile = Nitroglycerin-2D-skeletal.png		| ImageFile =
			| ImageFile1 = Nitroglycerin.svg
	| ImageFile_Ref = {{Chemboximage|correct|??}}
			| ImageFile1_Ref = {{Chemboximage|correct|??}}
	| ImageSize = 121
	| ImageName = Structural formula of zwitterionic nitroglycerin		| ImageName1 = Skeletal formula of zwitterionic nitroglycerin
	| ImageFile1 = Nirtoglycerin_3D_BallStick.png		| ImageFile2 = Nirtoglycerin_3D_BallStick.png
	| ImageFile1_Ref = {{Chemboximage|correct|??}}		| ImageFile2_Ref = {{Chemboximage|correct|??}}
			| ImageName2 = Ball and stick model of nitroglycerin
	| ImageSize1 = 121
			| ImageFile3 = Nitroglycerin-3D-vdW.png
	| ImageName1 = Ball and stick model of zwitterionic nitroglycerin
			| ImageFile3_Ref = {{Chemboximage|correct|??}}
	| IUPACName = 1,2,3-Trinitroxypropane
			| ImageName3 = Spacefill model of nitroglycerin
	| SystematicName = 2,3-Bis(nitrooxy)propyl nitrate
			| PIN = Propane-1,2,3-triyl trinitrate
	| OtherNames = 1,3-Dinitrooxypropan-2-yl nitrate<br />
			| SystematicName =
	Propane-1,2,3-triyl trinitrate
			| OtherNames = {{ubl|1,2,3-Tris(nitrooxy)propane|1,2,3-Trinitroxypropane|Glyceryl trinitrate|GTN|Nitro|TNG|Trinitroglycerin|''alpha'',''alpha'',''alpha''-Trinitroglycerin}}
	| Section1 = {{Chembox Identifiers
			| IUPACName =
	| CASNo = 55-63-0
			| Section1 = {{Chembox Identifiers
	| CASNo_Ref = {{cascite|correct|CAS}}
	| PubChem = 4510		| IUPHAR_ligand = 7053
			| CASNo = 55-63-0
	| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
			| CASNo_Ref = {{cascite|correct|CAS}}
	| ChemSpiderID = 4354
			| PubChem = 4510
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			| ChemSpiderID = 4354
	| UNII = G59M7S0WS3
	| UNII_Ref = {{fdacite|correct|FDA}}		| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| EINECS = 200-240-8		| UNII = G59M7S0WS3
			| UNII_Ref = {{fdacite|correct|FDA}}
	| UNNumber = 0143, 0144, 1204, 3064, 3319
	| DrugBank = DB00727		| EINECS = 200-240-8
			| UNNumber = 0143, 0144, 1204, 3064, 3319
	| KEGG = D00515
	| KEGG_Ref = {{keggcite|changed|kegg}}		| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
			| DrugBank = DB00727
	| MeSHName = Nitroglycerin
	| ChEBI = 28787		| KEGG = D00515
			| KEGG_Ref = {{keggcite|correct|kegg}}
	| ChEMBL = 730
			| MeSHName = Nitroglycerin
	| ChEMBL_Ref = {{ebicite|changed|EBI}}
			| ChEBI_Ref = {{ebicite|correct|EBI}}
	| ATCCode_prefix = C01
			| ChEBI = 28787
	| ATCCode_suffix = DA02
			| ChEMBL = 730
	| ATC_Supplemental = {{ATC|C05|AE01}}
			| ChEMBL_Ref = {{ebicite|correct|EBI}}
	| Beilstein = 1802063
	| Gmelin = 165859		| Beilstein = 1802063
			| Gmelin = 165859
	| SMILES = O=N(=O)OCC(CON(=O)=O)ON(=O)=O
	| SMILES1 = C(C(CO(=O))O(=O))O(=O)		| SMILES = C(C(CO(=O))O(=O))O(=O)
	| StdInChI = 1S/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2		| StdInChI = 1S/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2
	| StdInChI_Ref = {{stdinchicite|changed|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| InChI = 1/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2		| InChI = 1/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2
	| StdInChIKey = SNIOPGDIGTZGOP-UHFFFAOYSA-N		| StdInChIKey = SNIOPGDIGTZGOP-UHFFFAOYSA-N
	| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| InChIKey = SNIOPGDIGTZGOP-UHFFFAOYAR		| InChIKey = SNIOPGDIGTZGOP-UHFFFAOYAR
			}}
			| Section2 = {{Chembox Properties
			| C=3 | H=5 | N=3 | O=9
			| Appearance = Colorless or pale yellow, oily liquid or tetraclinic/orthorhombic crystal
			| Density = 1.5931 g/cm<sup>−3</sup>
			| MeltingPtC = 12.8
			| BoilingPtC = 218
			| BoilingPt_notes = Explodes
			| LogP = 2.154
			| Solubility = Slightly<ref name="osha.gov">{{Cite web |url=https://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |title=Occupational Safety and Health Guideline for Nitroglycerin |access-date=19 October 2016 |archive-url=https://web.archive.org/web/20130516192244/http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |archive-date=16 May 2013 |url-status=dead |df=dmy-all }}</ref>
			| Solvent =
			| SolubleOther = ], ], ], ], ]<ref name="osha.gov"/>
			}}
			| Section3 = {{Chembox Structure
			| Coordination = {{ubl
			| Tetragonal at C1, C2, and C3
			| Trigonal planar at N7, N8, and N9
			}}
			| MolShape = {{ubl
			| Tetrahedral at C1, C2, and C3
			| Dihedral at N7, N8, and N9
			}}
			}}
			| Section4 = {{Chembox Explosive
			| ShockSens = High
			| FrictionSens = High
			| DetonationV = 7,820{{nbsp}}m/s
			| REFactor = 1.50
			}}
			| Section5 = {{Chembox Thermochemistry
			| DeltaHf = −370{{nbsp}}kJ⋅mol<sup>−1</sup>
			| DeltaHc = −1.529{{nbsp}}MJ⋅mol<sup>−1</sup>
			}}
			| Section6 = {{Chembox Pharmacology
			| ATCCode_prefix = C01
			| ATCCode_suffix = DA02
			| ATC_Supplemental = {{ATC|C05|AE01}}
			| Bioavail = <1%
			| AdminRoutes = Intravenous, by mouth, under the tongue, topical
			| Metabolism = Liver
			| HalfLife = 3{{nbsp}}min
			| Legal_AU = S3
			| Legal_AU_comment =
			}}
			| Section7 = {{Chembox Hazards
			| GHSPictograms = {{GHS02}} {{GHS06}} {{GHS08}} {{GHS01}}
			| GHSSignalWord = '''Danger'''
			| HPhrases = {{H-phrases|202|205|241|301|311|331|370}}
			| PPhrases = {{P-phrases|210|243|250|260|264|270|271|280|302+352|410}}
			| NFPA-H = 3
			| NFPA-F = 2
			| NFPA-R = 4
			| PEL = C 0.2{{nbsp}}ppm (2{{nbsp}}mg/m<sup>3</sup>) <ref>{{PGCH|0456}}</ref>
			| MainHazards = Explosive, toxic
			}}<ref>{{cite web|url=http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingJR.htm|title=Hazard Rating Information for NFPA Fire Diamonds|url-status=dead|archive-url=https://web.archive.org/web/20150217114741/http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingJR.htm|archive-date=17 February 2015|df=dmy-all}}</ref>
	}}		}}
	| Section2 = {{Chembox Properties
	| C = 3
	| H = 5
	| N = 3
	| O = 9
	| ExactMass = 227.002578773 g mol<sup>-1</sup>
	| Appearance = Colorless liquid
	| Density = 1.6 g cm<sup>-3</sup> (at 15 °C)
	| MeltingPtC = 14
	| BoilingPtCL = 50
	| BoilingPtCH = 60
	| Boiling_notes = decomposes
	| pKa = 2.154
	}}
	| Section3 = {{Chembox Pharmacology
	| AdminRoutes = Intravenous, Oral, Sublingual, Topical, Transdermal
	| HalfLife = 3 min
	}}
	| Section6 = {{Chembox Explosive
	| ShockSens = high
	| FrictionSens = high
	| ExplosiveV = 7700 m s<sup>-1</sup>
	| REFactor = 1.50
	}}
	| Section7 = {{Chembox Hazards
	| EUIndex = 603-034-00-X
	| EUClass = E (Explosive) {{Hazchem T+}} {{Hazchem N}}
	| RPhrases = {{R3}}, {{R26/27/28}}, {{R33}}, {{R51/53}}
	| SPhrases = {{S1/2}}, {{S33}}, {{S35}}, {{S36/37}}, {{S45}}, {{S61}}
	| NFPA-H = 3
	| NFPA-F = 3
	| NFPA-R = 4
	}}
	}}
	'''Nitroglycerin''' ('''NG'''), (] spelling) also known as '''nitroglycerine''' (] spelling), '''trinitroglycerin''', '''trinitroglycerine''', '''1,2,3-trinitroxypropane''' and '''glyceryl trinitrate''', is a heavy, colorless, oily, explosive liquid obtained by ] ]. Since the 1860s, it has been used as an active ingredient in the manufacture of ]s, specifically ], and as such is employed in the ] and ] industries. Similarly, since the 1880s, it has been used by the military as an active ingredient, and a gelatinizer for ], in some solid ]s, such as ] and ].
			'''Nitroglycerin''' ('''NG''') (alternative spelling of nitroglycerine), also known as '''trinitroglycerol''' ('''TNG'''), '''nitro''', '''glyceryl trinitrate''' ('''GTN'''), or '''1,2,3-trinitroxypropane''', is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by ] ] with ] under conditions appropriate to the formation of the nitric acid ]. Chemically, the substance is a ] rather than a ], but the traditional name is retained. Discovered in 1846 by ],<ref>{{Cite web |title=Ascanio Sobrero |url=https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100514852 |access-date=2024-07-16 |website=Oxford Reference |language=en }}</ref> nitroglycerin has been used as an active ingredient in the manufacture of explosives, namely ], and as such it is employed in the ], ], and ] industries. It is combined with ] to form double-based ], used as a ] in artillery and firearms since the 1880s.
	Nitroglycerin is also used ] as a ] to treat ] conditions, such as ] and ]. It is one of the oldest and most useful drugs for treating heart disease by shortening or even preventing attacks of ]. Nitroglycerin comes in forms of tablets, sprays or patches.<ref></ref> Nitroglycerin can be used to help destroy ]<ref> "How dynamite could help destroy ]" Retrieved 2010-02-23</ref> as well as being used as a heart medication.
			As is the case for many other explosives, nitroglycerin becomes more and more prone to exploding (i.e. ]) as the temperature is increased. Upon exposure to heat above 218 °C at sea-level ], nitroglycerin becomes extremely unstable and tends to explode. When placed in vacuum, it has an ] temperature of 270 °C instead.<ref name=":0">{{Cite web |date=2013-05-16 |title=Occupational Safety and Health Guideline for Nitroglycerin |url=http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |access-date=2024-07-09 |archive-url=https://web.archive.org/web/20130516192244/http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |archive-date=16 May 2013 }}</ref> With a melting point of 12.8 °C, the chemical is almost always encountered as a thick and viscous fluid, changing to a crystalline solid when frozen.<ref name=":0" /><ref>{{Cite book |last=Haynes |first=W. M. |title=CRC Handbook of Chemistry and Physics |publisher=CRC Press |edition=97th |pages=3–540}}</ref> Although the pure compound itself is colorless, in practice the presence of ] impurities left over during production tends to give it a slight yellowish tint.
	== History ==
	Nitroglycerin was the first practical explosive stronger than ]. It was synthesized by chemist ] in 1847, working under ] at the ]. Sobrero initially called his discovery '''pyroglycerine''', and warned vigorously against its use as an explosive. It was later adopted as a commercially useful explosive by ]. He experimented with safer ways to handle the dangerous substance; his younger brother ] and several workers were killed in 1864 in a nitroglycerin explosion at the family's armaments factory in ], Sweden.<ref>.</ref>
			Due to its high boiling point and consequently low vapor pressure (0.00026 mmHg at 20 °C),<ref name=":0" /> pure nitroglycerin has practically no odor at room temperature, with a sweet and burning taste when ingested. Unintentional detonation may ensue when dropped, shaken, lit on fire, rapidly heated, exposed to sunlight and ozone, subjected to sparks and electrical discharges, or roughly handled.<ref>{{Cite web |title=Nitroglycerin, desensitized, liquid |url=https://cameochemicals.noaa.gov/chemical/12100 |url-status=live |archive-url=https://web.archive.org/web/20230826040417/https://cameochemicals.noaa.gov/chemical/12100 |archive-date=August 26, 2023 |access-date=July 9, 2024 |website=CAMEO Chemicals {{!}} NOAA}}</ref> Its ] to exploding is responsible for numerous devastating industrial accidents throughout its history. The chemical's characteristic reactivity may be reduced through the addition of desensitizing agents, which makes it less likely to explode. Clay (]) is an example of such an agent, forming dynamite, a much more easily handled composition. Addition of other desensitizing agents give birth to the various formulations of dynamite.
	A year later, Nobel founded ] in Germany, building an isolated factory in the Krümmel hills of ] near Hamburg. This business exported a liquid combination of nitroglycerin and ] known as "Blasting Oil", but it was extremely unstable and difficult to transport, as shown in numerous catastrophes. The buildings of the Krümmel factory were destroyed twice.<ref>.</ref>
			Nitroglycerin has been used for over 130 years ] as a potent ] (causing dilation of the vascular system) to treat ] conditions, such as ] and ]. Though it was previously known that these beneficial effects are due to nitroglycerin being converted to ], a potent venodilator, the enzyme for this conversion was only discovered to be mitochondrial ] (]) in 2002.<ref name="Chen et al. 2005 12159–12164">{{cite journal | journal = Proceedings of the National Academy of Sciences | year = 2005 | volume = 102 | pages = 12159–12164 | doi = 10.1073/pnas.0503723102 | pmid = 16103363 | last2 = Foster | first2 = M. W. | last3 = Zhang | first3 = J. | last4 = Mao | first4 = L. | last5 = Rockman | first5 = H. A. | last6 = Kawamoto | first6 = T. | last7 = Kitagawa | first7 = K. | last8 = Nakayama | first8 = K. I. | last9 = Hess | first9 = D. T. | last10 = Stamler | first10 = J. S. | title = An essential role for mitochondrial aldehyde dehydrogenase in nitroglycerin bioactivation | issue = 34 | pmc = 1189320 | last1 = Chen |first1=Z.| bibcode = 2005PNAS..10212159C | doi-access = free }}</ref> Nitroglycerin is available in ]s, sprays, ointments, and patches.<ref>{{Cite web |url=http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502@sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU= |title=Unknown, behind paywall, archived |access-date=14 April 2018 |archive-url=https://web.archive.org/web/20170510141029/http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502%40sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU%3d#db=hxh&AN=9703191987 |archive-date=10 May 2017 |url-status=dead |df=dmy-all }}</ref>
	In April 1866, three crates of nitroglycerin were shipped to ] for the ], who wished to experiment with its blasting capability to speed the construction of the {{convert|1659|ft|m|adj=on}} ] through the ]. One of the crates exploded, destroying a ] office in ] and killing 15 people, leading to a complete ban on the transport of liquid nitroglycerin in California. The on-site manufacture of nitroglycerin was thus required for the remaining hard-rock ] required for the completion of America's ].<ref>"", '']'', ].</ref>
			== History ==
	Liquid nitroglycerin was widely banned elsewhere as well and this finally led to Alfred Nobel & Company developing ] in 1867, made by mixing nitroglycerin with the ] (''kieselguhr'') found in the Krümmel hills. Similar mixtures, such as ] (1867), ] (1869), and ] (1875), mixed nitroglycerin with other inert absorbents — many combinations were tried to get around Nobel's tightly controlled patents. Dynamites containing ], which increases the viscosity of the mix, are commonly known as "gelatins".
			Nitroglycerin was the first practical explosive produced that was stronger than ]. It was synthesized by the Italian ] ] in 1846, working under ] at the ].<ref>{{cite journal|last=Sobrero |first=Ascagne |date=1847 |url=http://gallica.bnf.fr/ark:/12148/bpt6k29812/f247.item.zoom |title=Sur plusieur composés détonants produits avec l'acide nitrique et le sucre, la dextrine, la lactine, la mannite et la glycérine |trans-title=On several detonating compounds produced with nitric acid and sugar, dextrin, lactose, mannitol, and glycerin |journal=Comptes Rendus |volume=24 |pages=247–248}}</ref> Sobrero initially called his discovery ''pyroglycerine'' and warned vigorously against its use as an explosive.<ref>{{cite journal|last=Sobrero |first=Ascanio |date=1849 |url=https://babel.hathitrust.org/cgi/pt?id=iau.31858045931643;view=1up;seq=283 |title=Sopra alcuni nuovi composti fulminanti ottenuti col mezzo dell'azione dell'acido nitrico sulle sostante organiche vegetali |trans-title=On some new explosive products obtained by the action of nitric acid on some vegetable organic substances |journal=Memorie della Reale Accademia delle Scienze di Torino |series=2nd Series |volume=10 |pages=195–201}} On p. 197, Sobrero names nitroglycerin "pyroglycerine":
			:"Quelle gocciole costituiscono il corpo nuovo di cui descriverò ora le proprietà, e che chiamerò ''Piroglicerina''." (Those drops constitute the new substance whose properties I will now describe, and which I will call "pyroglycerine".)</ref>
			Nitroglycerin was adopted as a commercially useful explosive by ], who experimented with safer ways to handle the dangerous compound after his younger brother, ], and several factory workers were killed in an explosion at the Nobels' armaments factory in 1864 in ], Sweden.<ref>{{cite web |url=http://nobelprize.org/alfred_nobel/industrial/articles/vinterviken/emil.html |website=NobelPrize.org |title=Emil Nobel |access-date=6 October 2008 |archive-url=https://web.archive.org/web/20090115085417/http://nobelprize.org/alfred_nobel/industrial/articles/vinterviken/emil.html |archive-date=15 January 2009 |url-status=dead |df=dmy-all }}</ref>
	Following discoveries that ] helped to alleviate chest pain, Doctor William Murrell experimented with the use of nitroglycerin to alleviate ] and reduce ]. He began treating patients with small doses in 1878, and it was soon adopted into widespread use after he published his results in '']'' in 1879. The medical establishment used the name "glyceryl trinitrate" or "trinitrin" to avoid alarming patients who associated nitroglycerin with explosions.<ref>Sneader, Walter. ''Drug Discovery: A History''. John Wiley and Sons, 2005 ISBN 0471899801.</ref>
			{{stack|]'s ] from 1864]]}}
	=== Wartime production rates ===
	Large quantities of nitroglycerin were manufactured in both World Wars for use in military propellants. In ] ], the largest propellant factory in the United Kingdom, was producing 800 ]s (812 ]s) of Cordite RDB per week. This needed 336 tons of nitroglycerin per week (assuming no losses in production). The ] had its own factory at ] in Dorset, England. A large cordite factory was built in ] in World War I. The ] Cordite factory at ] was designed to produce {{convert|1500000|lb|t|abbr=on}} of Cordite per month. It required 286 tonnes of nitroglycerin per month.
			One year later, Nobel founded ] in Germany and built an isolated factory in the Krümmel hills of ] near ]. This business exported a liquid combination of nitroglycerin and ] called "Blasting Oil", but this was extremely unstable and difficult to handle, as evidenced in numerous catastrophes.<ref name="The Manufacture of High Explosives">{{cite web |last1=Ramsay |first1=Sir William |title=The Manufacture of High Explosives |url=https://www.scientificamerican.com/article/the-manufacture-of-high-explosives/ |website=Scientific American |date=28 December 1907 |publisher=Springer Nature |access-date=4 March 2024 |ref=Explains the context and process of the manufacturing of NG at Nobel's factories}}</ref> The buildings of the Krümmel factory were destroyed twice.<ref>{{cite web|url=http://nobelprize.org/alfred_nobel/industrial/articles/krummel/index.html |website=NobelPrize.org |title=Krümmel |url-status=dead |archive-url=https://web.archive.org/web/20060710005656/http://nobelprize.org/alfred_nobel/industrial/articles/krummel/index.html |archive-date=10 July 2006 }}.</ref>
	== Instability and desensitization ==
	In its pure form, it is a primary ] (physical shock can cause it to explode) and degrades over time to even more unstable forms. This makes it highly dangerous to transport or use. In this undiluted form, it is one of the more powerful explosives, comparable to the more recent ] and ], as well as the ] ]—which contains 90-92% ] as its active ingredient.
			In April 1866, several crates of nitroglycerin were shipped to ], three of which were destined for the ], which planned to experiment with it as a blasting explosive to expedite the construction of the {{convert|1659|ft|m|adj=mid|-long}} ] through the ]. One of the remaining crates exploded, destroying a ] company office in ] and killing 15 people. This led to a complete ban on the transportation of liquid nitroglycerin in California. The on-site manufacture of nitroglycerin was thus required for the remaining hard-rock ] required for the completion of the ] in North America.<ref>{{cite web|url=https://www.pbs.org/wgbh/amex/tcrr/peopleevents/e_nitro.html |title=Transcontinental Railroad – People & Events: Nitroglycerin |website=] |publisher=]}}</ref>
	Early in the history of this explosive it was discovered that liquid nitroglycerin can be "desensitized" by cooling to 5 to 10&nbsp;]&nbsp;(40 to 50&nbsp;]), at which temperature it freezes, contracting upon solidification. However, later thawing can be extremely sensitizing, especially if impurities are present or if warming is too rapid.<ref>{{cite web|url=http://www.logwell.com/tales/second_nitro_death.html | title=Tales of Destruction-Thawing can be Hell}}</ref> It is possible to chemically "desensitize" nitroglycerin to a point where it can be considered approximately as "safe" as modern ] formulations, by the addition of approximately 10-30% ], ],<ref>{{cite web|url=http://www.logwell.com/tales/red_glycerin.html | title=Tales of Destruction-Is Nitroglicerine in This?}}</ref> or ] (percentage varies with the desensitizing agent used). Desensitization requires extra effort to reconstitute the "pure" product. Failing this, it must be assumed that desensitized nitroglycerin is substantially more difficult to detonate, possibly rendering it useless as an explosive for practical application.
			On Christmas Day 1867, an attempt to dispose of nine canisters of Blasting Oil that had been illegally stored at the White Swan Inn in the centre of ] resulted in an explosion on the Town Moor that killed eight people. In June 1869, two one-ton wagons loaded with nitroglycerin, then known locally as Powder-Oil, exploded in the road at the North Wales village of ]. The explosion led to the loss of six lives, many injuries and much damage to the village. Little trace was found of the two horses. The UK Government was so alarmed at the damage caused and what could have happened in a city location (these two tons were part of a larger load coming from Germany via Liverpool) that they soon passed the Nitro-Glycerine Act of 1869.<ref>North Wales Daily Post newspaper of October 14th 2018.</ref> Liquid nitroglycerin was widely banned elsewhere, as well, and these legal restrictions led to Alfred Nobel and his company's developing dynamite in 1867. This was made by mixing nitroglycerin with ] ("''Kieselguhr''{{-"}} in German) found in the Krümmel hills. Similar mixtures, such as "dualine" (1867), "lithofracteur" (1869), and "]" (1875), were formed by mixing nitroglycerin with other inert absorbents, and many combinations were tried by other companies in attempts to get around Nobel's tightly held patents for dynamite.
	A serious problem in the use of nitroglycerin results from its high freezing point 13&nbsp;]&nbsp;(55&nbsp;]). Solid nitroglycerin is much less sensitive to shock than the liquid, a feature common in explosives; in the past it was often shipped in the frozen state, but this resulted in a high number of accidents during the thawing process by the end user just prior to use. This disadvantage is overcome by using mixtures of nitroglycerin with other polynitrates; for example, a mixture of nitroglycerin and ] freezes at -29&nbsp;]&nbsp;(-20&nbsp;]).<ref name="fn_1">{{cite web|url=http://www.britannica.com/nobel/micro/426_77.html | work=Britannica | title=nitroglycerin | accessdate=2005-03-23 }}</ref>
			Dynamite mixtures containing ], which increases the viscosity of the mix, are commonly known as "gelatins".
	== Detonation ==
	Nitroglycerin and any dilutents can certainly ], i.e. burn. However, the explosive power of nitroglycerin is derived from ]: energy from the initial decomposition causes a pressure wave or gradient that detonates the surrounding fuel. This is a self-sustained ] that propagates through the explosive medium at some 30 times the speed of sound as a near-instantaneous pressure-induced decomposition of the fuel into a white hot gas. Detonation of nitroglycerin generates gases that would occupy more than 1,200 times the original volume at ordinary room temperature and pressure. Moreover, the heat liberated raises the temperature to about {{convert|5000|C}}.<ref>Encyclopaedia Britannica.</ref> This is totally different from ], which depends solely upon available fuel regardless of pressure or shock.
			Following the discovery that ] helped alleviate chest pain, the physician ] experimented with the use of nitroglycerin to alleviate angina pectoris and to reduce the ]. He began treating his patients with small diluted doses of nitroglycerin in 1878, and this treatment was soon adopted into widespread use after Murrell published his results in the journal '']'' in 1879.<ref>{{cite journal|last=Murrell |first=William |date=1879 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.d0000772988;view=1up;seq=78 |title=Nitroglycerin as a remedy for angina pectoris |journal=The Lancet |volume=1 |issue=2890 |pages=80–81, 113–115, 151–152, 225–227|doi=10.1016/s0140-6736(02)46032-1 |pmc=5901592 }}</ref><ref name="ReferenceA">{{cite book|last=Sneader |first=Walter |title=Drug Discovery: A History |publisher=John Wiley and Sons |date=2005 |isbn=978-0-471-89980-8}}</ref> A few months before his death in 1896, Alfred Nobel was prescribed nitroglycerin for this heart condition, writing to a friend: "Isn't it the irony of fate that I have been prescribed nitro-glycerin, to be taken internally! They call it Trinitrin, so as not to scare the chemist and the public."<ref>{{cite web|url=http://www.beyonddiscovery.org/content/view.txt.asp?a=318|title=History of TNG|website=beyonddiscovery.org|access-date=14 April 2018|archive-url=https://web.archive.org/web/20101101191907/http://www.beyonddiscovery.org/content/view.txt.asp?a=318|archive-date=1 November 2010|url-status=dead}}</ref> The medical establishment also used the name "glyceryl trinitrate" for the same reason.
	== Manufacturing ==
	The industrial manufacturing process often uses a nearly 50:50 mixture of concentrated ] and concentrated ]. This can be produced by mixing ] (quite costly pure nitric acid in which oxides of nitrogen have been removed, as opposed to red fuming nitric acid) and concentrated sulfuric acid. More often, this mixture is attained by the cheaper method of mixing fuming sulfuric acid, also known as ], (sulfuric acid containing excess ]) and ] nitric acid (consisting of around 70% nitric acid, the rest being water).
			=== Wartime production rates ===
	The sulfuric acid produces protonated nitric acid species, which are attacked by glycerin's ] ] atoms. The ] ] is thus added as an ester C-O-NO<sub>2</sub> and water is produced. This is different from an aromatic nitration reaction in which ]s are the active species in an electrophilic attack of the molecules' ring system.
			Large quantities of nitroglycerin were manufactured during ] and ] for use as military propellants and in ] work. During World War I, ], the largest propellant factory in the ], produced about 800 ]s of ] per week. This amount required at least 336 tonnes of nitroglycerin per week (assuming no losses in production). The ] had its own factory at the ], in ], England. A large cordite factory was also built in Canada during World War I. The ] cordite factory at ], was designed to produce {{convert|1500000|lb|t|abbr=on}} of cordite per month, requiring about 286 tonnes of nitroglycerin per month.
			== Instability and desensitization ==
	The addition of glycerin results in an ] (i.e., heat is produced), as usual for mixed acid nitrations. However, if the mixture becomes too hot, it results in runaway, a state of accelerated nitration accompanied by the destructive oxidizing of organic materials of nitric acid and the release of very poisonous brown ] gas at high risk of an explosion. Thus, the glycerin mixture is added slowly to the reaction vessel containing the mixed acid (not acid to glycerin). The nitrator is cooled with cold water or some other coolant mixture and maintained throughout the glycerin addition at about {{convert|22|C}}, much below which the esterification occurs too slowly to be useful. The nitrator vessel, often constructed of iron or lead and generally stirred with compressed air, has an emergency trap door at its base, which hangs over a large pool of very cold water and into which the whole reaction mixture (called the charge) can be dumped to prevent an explosion, a process referred to as drowning. If the temperature of the charge exceeds about {{convert|30|C}} (actual value varying by country) or brown fumes are seen in the nitrator's vent, then it is immediately drowned.
			In its undiluted form, nitroglycerin is a ], with physical shock causing it to explode. If it has not been adequately purified during manufacture it can degrade over time to even more unstable forms. This makes nitroglycerin highly dangerous to transport or use. In its undiluted form, it is one of the world's most powerful explosives, comparable to the more recently developed ] and ].
			Early in its history, liquid nitroglycerin was found to be "]" by freezing it at a temperature below {{Convert|45|to|55|F|C}} depending on its purity.<ref name="Tallini5">{{Cite web |title=Is Nitroglycerine In This? Page 5 |url=https://www.logwell.com/tales/frozen_nitroglycerin.html |access-date=2024-02-20 |website=www.logwell.com}}</ref> Its sensitivity to shock while frozen is somewhat unpredictable: "It is more insensitive to the shock from a ] or a rifle ball when in that condition but on the other hand it appears to be more liable to explode on breaking, crushing, tamping, etc."<ref name="LSMI1">{{cite journal |url=https://www.michigan.gov/documents/deq/GIMDL-LSMI1911B_301826_7.pdf |title=Accidents in the Transportation, Storage, and Use of Explosives |first=Charles S. |last=Hurter |date=August 22, 1911 |volume=16 |journal=Proceedings of the Lake Superior Mining Institute |page=70}}</ref> Frozen nitroglycerin is much less energetic than liquid, and so must be thawed before use.<ref name="LSMI2">{{cite journal |url=https://www.michigan.gov/documents/deq/GIMDL-LSMI1911C_301829_7.pdf |title=Accidents in the Transportation, Storage, and Use of Explosives |first=Charles S. |last=Hurter |date=August 22, 1911 |volume=16 |journal=Proceedings of the Lake Superior Mining Institute |page=71}}</ref> Thawing it out can be extremely sensitizing, especially if impurities are present or the warming is too rapid.<ref name="Tallini4">{{cite web |last=Tallini |first=Rick F. |title=Tales of Destruction...Thawing Can Be Hell |url=http://www.logwell.com/tales/second_nitro_death.html |website=Analog |series= |publisher=Analog Services, Inc.}}</ref> ] or another polynitrate may be added to lower the melting point and thereby avoid the necessity of thawing frozen explosive.<ref name="fn_1">{{cite encyclopedia|url=https://www.britannica.com/nobel/micro/426_77.html | encyclopedia=Encyclopaedia Britannica | title=Nitroglycerin | access-date=2005-03-23 |archive-url=https://web.archive.org/web/20020912025024/https://www.britannica.com/nobel/micro/426_77.html |archive-date=2002-09-12 }}</ref>
	== Use as an explosive and a propellant ==
	{{Main|Dynamite|Ballistite|Cordite|smokeless powder|Gelignite}}
	]'s ] from ].]]
	The main use of nitroglycerin, by tonnage, is in explosives such as dynamite and in propellants.
			Chemically "desensitizing" nitroglycerin is possible to a point where it can be considered about as "safe" as modern ]s, such as by the addition of ], ], or ].<ref name="Tallini12">{{cite web |last=Tallini |first=Rick F. |title=Tales of Destruction...Is Nitroglycerin In This? |url=http://www.logwell.com/tales/red_glycerin.html |series= |publisher=Analog Services, Inc.}}</ref> The nitroglycerin may have to be extracted from the desensitizer chemical to restore its effectiveness before use, for example by adding water to draw off ethanol used as a desensitizer.<ref name="Tallini12"/>
	Nitroglycerin is an oil that may explode with heat, pressure or when it burns. It is extremely unstable, therefore dropping or bumping a container can also make it explode.<ref></ref>
			== Detonation ==
	] developed the use of nitroglycerin as a blasting explosive by mixing the nitroglycerine with inert ] particularly ]. He named this explosive ] and ] it in 1867. It was supplied ready for use in the form of ''sticks'', individually wrapped in greased water-proof paper. Dynamite and similar explosives were widely adopted for civil engineering tasks, such as building railway tunnels and cuttings; and for quarrying.
			When nitroglycerin explodes, the products after cooling are given by:
			:2{{chem2|C3H5N3O9}} → 6{{CHEM2|CO2}} + 5{{CHEM2|H2O}} + 3{{CHEM2|N2}} + {{CHEM2|O}}
			The heat released can be calculated from the heats of formation. Using &minus;371&nbsp;kJ/] for the heat of formation of condensed phase nitroglycerin<ref>{{Cite web |last=Informatics |first=NIST Office of Data and |title=Nitroglycerin |url=https://webbook.nist.gov/cgi/cbook.cgi?ID=C55630&Units=SI&Mask=FFF |access-date=2024-02-20 |website=webbook.nist.gov |language=en}}</ref> gives 1414&nbsp;kJ/mol released if forming water vapor, and 1524 if forming liquid water.
	Nitroglycerin was also adapted as a military propellant, for use in guns and rifles. ], invented in ] in 1886, was one of the first military propellants to replace ]; but it was based on nitrocellulose, not nitroglycerin. It was later found to be unstable.
			The detonation velocity of nitroglycerin is 7820 meters per second, which is about 113% the speed of ]. Accordingly, nitroglycerin is considered to be a high-] explosive, which is to say, it has excellent shattering ability. The heat liberated during detonation raises the temperature of the gaseous byproducts to about {{convert|5000|C|F|-3}}.<ref name="fn_1"/> With a standard enthalpy of explosive decomposition of &minus;1414&nbsp;kJ/] and a molecular weight of 227.0865&nbsp;g/mol, nitroglycerin has a specific explosive energy density of 1.488&nbsp;] per gram, or 6.23&nbsp;kJ/g, making nitroglycerin 49% more energetic on a mass basis than the standard definitional value assigned to TNT (precisely 1&nbsp;kcal/g).
	Nitroglycerin is a high explosive which is so unstable that the slightest jolt, friction, or impact can cause it to detonate. The molecule contains oxygen, nitrogen, and carbon in weak bonds; when it explodes great energy is released as the atoms rearrange to form new molecules with strong, stable bonds like N<sub>2</sub> and CO. It is the speed of the decomposition reaction which makes it such a violent explosive. A supersonic wave passing through the material causes it to decompose almost instantly. This instantaneous destruction of all molecules is called a detonation, and the destructive blast results from the rapid expansion of hot gases. Nitroglycerin has an advantage over some other high explosives, that no visible smoke is produced, therefore acting as a "smokeless powder".<ref></ref>
			== Manufacturing ==
	Alfred Nobel then developed ], by combining nitroglycerin and ]. He patented it in 1887. Ballistite was adopted by a number of European governments, as a military propellant. ] was the first to adopt it. However, it was not adopted by the British Government. They, together with the British Commonwealth countries, adopted ], which had been developed by Sir ] and ], in 1889. The original Cordite Mk I consisted of 58% nitroglycerine, 37% guncotton and 5% ]. Ballistite and cordite were both manufactured in the forms of ''cords''.
			{{More citations needed|date=August 2024}}
			]
			Nitroglycerin can be produced by acid-catalyzed nitration of ] (glycerin).<ref>{{cite book |last1=Lewis |first1=Richard J., Sr |title=Hawley's Condensed Chemical Dictionary |date=15 March 2007 |publisher=John Wiley & Sons, Inc |location=United States |isbn=978-0-471-76865-4 |page=897 |edition=15th}}</ref>
	]s were originally developed using nitrocellulose as the sole explosive ingredient; and were therefore known as ''single base'' propellants. A range of smokeless powders that contain both nitrocellulose and nitroglycerin, known as ''double base'' propellants, were also developed. Smokeless powders were originally supplied only for military use; however they were also soon developed for civilian use and were quickly adopted for sport. Some are known as sporting powders. ''Triple base'' propellants contain nitrocellulose, nitroglycerin and nitroguanidine, but are reserved mainly for extremely high calibre ammunition rounds such as those used in tank cannons and naval guns.
			The industrial manufacturing process often reacts ] with a nearly 1:1 mixture of concentrated ] and concentrated ]. This can be produced by mixing ]—a quite expensive pure nitric acid in which the oxides of nitrogen have been removed, as opposed to ], which contains ]—and concentrated ]. More often, this mixture is attained by the cheaper method of mixing fuming ], also known as ]—] containing excess ]—and ] nitric acid (consisting of about 70% ], with the rest being water).<ref>{{Cite book |last=Wexler |first=Philip |title=Encyclopedia of Toxicology |date=April 7, 2014 |publisher=Academic Press |isbn=978-0123864543 |edition=3rd |location=USA |pages=569 |language=en |trans-title=}}</ref>
	'''Blasting gelatin''', also known as ], was invented by Nobel in 1875, using nitroglycerine, wood pulp, and sodium or potassium nitrates. This was an early low-cost, flexible explosive.
			The ] produces ] ] species, which are attacked by ]'s ] ] atoms. The ] ] is thus added as an ester C−O−NO<sub>2</sub> and water is produced. This is different from an electrophilic aromatic substitution reaction in which ]s are the ].
	=== Nitroglycerin and dynamite ===
	Alfred Nobel discovered that mixing nitroglycerin with diatomaceous earth would turn the liquid into a paste, called dynamite. An advantage of dynamite was that it could be cylinder-shaped for insertion into the drilling holes used for mining. Nobel received U.S. patent number 78,317 for his dynamite in 1867.<ref></ref>
			The addition of ] results in an ] (i.e., heat is produced), as usual for mixed-acid nitrations. If the mixture becomes too hot, it results in a runaway reaction, a state of accelerated nitration accompanied by the destructive ] of organic materials by the hot ] and the release of poisonous ] gas at high risk of an explosion. Thus, the ] mixture is added slowly to the reaction vessel containing the mixed acid (not acid to glycerin). The nitrator is cooled with cold water or some other coolant mixture and maintained throughout the ] addition at about {{convert|22|C|F}}, hot enough for esterification to occur at a fast rate but cold enough to avoid runaway reaction. The nitrator vessel, often constructed of ] or ] and generally stirred with ], has an emergency trap door at its base, which hangs over a large pool of very cold water and into which the whole reaction mixture (called the charge) can be dumped to prevent an explosion, a process referred to as drowning. If the temperature of the charge exceeds about {{convert|30|C|F}} (actual value varying by country) or brown fumes are seen in the nitrator's vent, then it is immediately drowned.
	== Medical applications ==
	=== Medical use ===<!-- This section is linked from ] -->
	{{Main|Glyceryl trinitrate (pharmacology)}}
			== Use as an explosive and a propellant ==
	Nitroglycerin belongs to a group of drugs called nitrates, which includes many other nitrates like ] (Isordil) and ] (Imdur, Ismo, Monoket).<ref name="Nitroglycerin Article"></ref> In ], where it is generally called glyceryl trinitrate, nitroglycerin is used as a ] medication (under the trade names '''Nitrospan''', '''Nitrostat''', '''Nitrol''', and '''Tridil''', amongst others). It is used as a medicine for ] (]) in tablets, ointment, solution for intravenous use, transdermal patches ('''Trinipatch''', '''Transderm Nitro''', '''Nitro-Dur'''), or sprays administered ]ly ('''Nitrolingual Pump Spray''', '''Natispray'''). Patients who experience angina when doing certain physical activities can often prevent symptoms by taking nitroglycerin 5 to 10 minutes before the activity. Some forms of nitroglycerin last much longer in the body than others. These may come in the form of a pill taken one, two, or three times per day, or even as a patch. It has been shown that round-the-clock exposure to nitrates can cause the body to stop responding normally to this medicine. Experts recommend that the patches be removed at night, allowing the body a few hours to restore its responsiveness to nitrates. Shorter-acting preparations can be used several times a day with less risk of the body getting used to this drug.<ref>.</ref>
			{{Main|Dynamite|Ballistite|Cordite|smokeless powder|Gelignite}}
	Nitroglycerin was synthesized in 1846, and was first used to treat anginal attacks in 1879.
			Nitroglycerin is an oily liquid that explodes when subjected to heat, shock, or flame. The main use of nitroglycerin, by ], is in explosives such as dynamite and in propellants as an ingredient. However, its sensitivity has limited the usefulness of nitroglycerin as a military explosive; less sensitive explosives such as ], ], and ] have largely replaced it in munitions.
			] developed the use of nitroglycerin as a blasting explosive by mixing nitroglycerin with inert ]s, particularly "''Kieselgur''", or ]. He named this explosive dynamite and ] it in 1867.<ref>{{cite news|url=http://inventors.about.com/od/dstartinventions/a/Alfred_Nobel.htm|title=Alfred Nobel and the History of Dynamite|first=Mary|last=Bellis|work=About.com Money|access-date=10 November 2009|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828185843/https://www.thoughtco.com/history-of-dynamite-1991564|url-status=dead}}</ref> It was supplied ready for use in the form of sticks, individually wrapped in greased waterproof paper. Dynamite and similar explosives were widely adopted for ] tasks, such as in drilling ] and ] ]s, for ], for clearing farmland of stumps, in ], and in ]. Likewise, ]s have used dynamite for construction and demolition work.
	] is due to an inadequate flow of blood and oxygen to the heart, which is essential for the production of energy. The heart muscle must produce and use the energy in order to be able to pump blood through the lungs and into the arteries. It is believed that nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart.<ref>http://www.medicinenet.com/nitroglycerin/article.htm</ref> The principal action of nitroglycerin is ]&mdash;widening of the ]s. Nitroglycerin will dilate veins more than arteries. It also lowers the pressure in the arteries against which the heart must pump.<ref name="Nitroglycerin Article"/> Dilating the veins decreases cardiac preload and leads to the following therapeutic effects during episodes of ]:
	* subsiding of chest pain
	* decrease of ]
	* increase of heart rate.
	* ]
			Nitroglycerin has been used in conjunction with ], a process used to recover ] and ] from ] formations. The technique involves displacing and detonating nitroglycerin in natural or hydraulically induced fracture systems, or displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized ].<ref name="recovery">{{cite journal|last1=Miller|first1=J. S.|last2=Johansen|first2=R. T.|date=1976|title=Fracturing Oil Shale with Explosives for In Situ Recovery.|journal=Shale Oil, Tar Sand and Related Fuel Sources|pages=151|bibcode=1976sots.rept...98M|url=https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/19_2_LOS%20ANGELES_04-74__0060.pdf|access-date=27 March 2015|archive-date=2 October 2018|archive-url=https://web.archive.org/web/20181002204137/https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/19_2_LOS%20ANGELES_04-74__0060.pdf|url-status=dead}}</ref>
	These effects arise because nitroglycerin is converted to ] in the body by mitochondrial ],<ref>Chen et al., Proc. Natl. Acad. Sci. USA (2005) 102:12159-64.</ref> and nitric oxide is a natural vasodilator. Recently, it has also become popular in an ] use at reduced (0.2%) concentration in ointment form as an effective treatment for ].
			Nitroglycerin has an advantage over some other high explosives that on detonation it produces practically no visible smoke. Therefore, it is useful as an ingredient in the formulation of various kinds of ].<ref>{{cite web|url=http://www.ch.ic.ac.uk/rzepa/mim/environmental/html/nitroglyc_text.htm|title=Nitroglycerin}}</ref>
	=== Side effects ===
			Alfred Nobel then developed ], by combining nitroglycerin and ]. He patented it in 1887. Ballistite was adopted by a number of European governments, as a military propellant. Italy was the first to adopt it. The British government and the Commonwealth governments adopted ] instead, which had been developed by Sir ] and Sir ] of the United Kingdom in 1889. The original Cordite Mk&nbsp;I consisted of 58% nitroglycerin, 37% guncotton, and 5.0% ]. Ballistite and cordite were both manufactured in the form of "cords".
	The side effects of nitroglycerin include lack of sexual desire, headache, painful urination and increased ] movements.{{Citation needed|date=November 2008}} Patients are often told to sit or lie down during and immediately after taking nitroglycerin to reduce the risk of low blood pressure. A drop in blood pressure can be accompanied by weakness or dizziness.<ref></ref>
			Smokeless powders were originally developed using nitrocellulose as the sole explosive ingredient. Therefore, they were known as single-base propellants. A range of smokeless powders that contains both nitrocellulose and nitroglycerin, known as double-base propellants, were also developed. Smokeless powders were originally supplied only for military use, but they were also soon developed for civilian use and were quickly adopted for sports. Some are known as sporting powders. Triple-base propellants contain nitrocellulose, nitroglycerin, and ], but are reserved mainly for extremely high-caliber ammunition rounds such as those used in tank cannons and ]. Blasting gelatin, also known as ], was invented by Nobel in 1875, using nitroglycerin, ], and ] or ]. This was an early, low-cost, flexible explosive.
	Shortly after the invention of nitroglycerin, this substance was noticed to be capable of inducing a violent headache. Headaches are the most prominent side effect of nitrate therapy. This was due to the release of nitric oxide (NO) by nitroglycerin. Such studies have led to propose that NO may be the causative molecule in migraine pain. The importance of NO as a potential initiator of the migraine attack opens new directions for other vascular headaches and pharmacological treatment of migraines.<ref></ref>
	=== Forms ===		== Medical use ==
			{{Main|Medical use of nitroglycerin}}
	]
			Nitroglycerin belongs to a group of drugs called nitrates, which includes many other nitrates like ] (Isordil) and ] (Imdur, Ismo, Monoket).<ref name="Nitroglycerin Article">{{cite web|url=http://www.medicinenet.com/nitroglycerin/article.htm|title=nitroglycerin, Nitro-Bid: Drug Facts, Side Effects and Dosing|first=Omudhome|last=Ogbru|work=MedicineNet}}</ref> These agents all exert their effect by being converted to ] in the body by mitochondrial ] (]),<ref name="Chen et al. 2005 12159–12164"/> and nitric oxide is a potent natural vasodilator.
			]
	A common form of medical nitroglycerin is a small white tablet that patients slip under the tongue. Another form is nitroglycerin sprays that are a convenient alternative for someone awakened by angina attacks at night. These two forms are not for routine use, only to be used at the onset of chest pain. A patch is another form of nitroglycerin. The medication contained in the patch is slowly released and absorbed through the skin and into the bloodstream, however it will not relieve an attack that has already started.<ref></ref>
			In ], nitroglycerin is probably most commonly prescribed for ], a painful symptom of ] caused by inadequate flow of blood and oxygen to the heart and as a potent antihypertensive agent. Nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart and the heart's energy demand.<ref name="Nitroglycerin Article"/> There are many formulations on the market at different doses. At low doses, nitroglycerin dilates veins more than arteries, thereby reducing ] (volume of blood in the heart after filling); this is thought to be its primary mechanism of action. By decreasing preload, the heart has less blood to pump, which decreases oxygen requirement since the heart does not have to work as hard. Additionally, having a smaller preload reduces the ventricular transmural pressure (pressure exerted on the walls of the heart), which decreases the compression of heart arteries to allow more blood to flow through the heart. At higher doses, it also dilates arteries, thereby reducing ] (decreasing the pressure against which the heart must pump).<ref name="Nitroglycerin Article"/> An improved ratio of myocardial oxygen demand to supply leads to the following therapeutic effects during episodes of angina pectoris: subsiding of chest pain, decrease of ], increase of heart rate, and ]. Patients experiencing angina when doing certain physical activities can often prevent symptoms by taking nitroglycerin 5 to 10 minutes before the activity. Overdoses may generate ].<ref>{{cite journal| pmid=3917597 | volume=55 | issue=1 | title=Association of methemoglobinemia and intravenous nitroglycerin administration | year=1985 | journal=] | pages=181–183 | last1=Kaplan | first1=K. J. | last2=Taber | first2=M. | last3=Teagarden | first3=J. R. | last4=Parker | first4=M. | last5=Davison | first5=R. | doi=10.1016/0002-9149(85)90324-8}}</ref><ref>{{cite web|url=http://www.intramed.net/contenidover.asp?contenidoID=86507|title=IntraMed – Bienvenido|website=www.intramed.net|access-date=14 April 2018}}</ref>
	Since 1879, nitroglycerin pills have been a standard treatment for angina and heart attacks, but it wasn't until the 1970s that researchers understood that the body converts nitroglycerin into nitric oxide, a messenger molecule that tells the smooth muscles surrounding blood vessels to relax.<ref></ref>
			Nitroglycerin is available in tablets, ointment, solution for ] use, ]es, or sprays administered ]ly. Some forms of nitroglycerin last much longer in the body than others. Nitroglycerin as well as the onset and duration of action of each form is different. The sublingual or tablet spray of nitroglycerin has a two minute onset and twenty five minute duration of action. The oral formulation of nitroglycerin has a thirty five minute onset and a duration of action of 4–8 hours. The transdermal patch has an onset of thirty minutes and a duration of action of ten to twelve hours. Continuous exposure to nitrates has been shown to cause the body to stop responding normally to this medicine. Experts recommend that the patches be removed at night, allowing the body a few hours to restore its responsiveness to nitrates. Shorter-acting preparations of nitroglycerin can be used several times a day with less risk of developing tolerance.<ref>{{cite web|url=http://connection.ebscohost.com/c/articles/9703191987|title=Nitroglycerin for angina, February 1997, Vol. 7|access-date=9 November 2009|archive-url=https://web.archive.org/web/20170510141029/http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502%40sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU%3d#db=hxh&AN=9703191987|archive-date=10 May 2017|url-status=dead}}</ref> Nitroglycerin was first used by ] to treat angina attacks in 1878, with the discovery published that same year.<ref name="ReferenceA"/><ref>{{cite journal | pmc = 1798737| year = 1971| last1 = Smith| first1 = E.| title = William Murrell, physician and practical therapist| journal = British Medical Journal| volume = 3| issue = 5775| pages = 632–633| last2 = Hart| first2 = F. D.| pmid = 4998847| doi=10.1136/bmj.3.5775.632}}</ref>
	When a pill is needed the person places it under the tongue and allows it to dissolve, which usually takes about 20–30 seconds. Nitroglycerin can also be chewed, but is less effective when it is swallowed without being dissolved. Its actions make a gentle tingling sensation under the tongue. Nitroglycerin is more effective when taken at the very inception of chest discomfort. After taking the nitroglycerin pill, relief often follows within one to two minutes, but not all types of chest pain respond to nitroglycerin.<ref></ref>
			{{clear left}}
	== Industrial exposure ==		== Industrial exposure ==
	Infrequent exposure to high doses of nitroglycerin can cause severe headaches known as "NG head". These headaches can be severe enough to incapacitate some people; however, humans develop a tolerance to and dependence on nitroglycerin after long-term exposure. Withdrawal can (rarely) be fatal; withdrawal symptoms include headaches and heart problems; with re-exposure to nitroglycerin, these symptoms may disappear.		Infrequent exposure to high doses of nitroglycerin can cause severe ]s known as "NG head" or "bang head". These headaches can be severe enough to incapacitate some people; however, humans develop a ] to and dependence on nitroglycerin after long-term exposure. Although rare, withdrawal can be fatal;<ref name="CDT">{{cite book|last1=Amdur |first1=Mary O. |last2=Doull |first2=John |title=Casarett and Doull's Toxicology |edition=4th |publisher=Elsevier |date=1991 |isbn=978-0071052399}}</ref>symptoms include chest pain and other heart problems. These symptoms may be relieved with re-exposure to nitroglycerin or other suitable organic nitrates.<ref name="Jr.Krieger2001">{{cite book| first1=John B. Jr. |last1=Sullivan |first2=Gary R. |last2=Krieger|title=Clinical Environmental Health and Toxic Exposures: Latex|url=https://books.google.com/books?id=PyUSgdZUGr4C&pg=PA264|access-date=23 April 2013|year=2001|publisher=Lippincott Williams & Wilkins|isbn=978-0-683-08027-8|pages=264}}</ref>
			For workers in nitroglycerin (NTG) manufacturing facilities, the effects of withdrawal sometimes include "Sunday heart attacks" in those experiencing regular nitroglycerin exposure in the workplace, leading to the development of tolerance for the venodilating effects. Over the weekend, the workers lose the tolerance, and when they are re-exposed on Monday, the drastic ] produces a ], dizziness, and a headache. This is referred to as "Monday disease."<ref name="Short history">{{cite journal |last1=Marsh |first1=N. |last2=Marsh |first2=A. |title=A short history of nitroglycerine and nitric oxide in pharmacology and physiology |journal=Clinical and Experimental Pharmacology and Physiology |volume=27 |issue=4 |pages=313–319 |year=2000 |pmid=10779131 |doi= 10.1046/j.1440-1681.2000.03240.x|s2cid=12897126 }}</ref><ref name="Toxicology">{{cite book|author=Assembly of Life Sciences (U.S.) Advisory Center on Toxicology|title=Toxicological Reports|url=https://books.google.com/books?id=fEQrAAAAYAAJ&pg=PA115|access-date=23 April 2013|publisher=National Academies|pages=115|id=NAP:11288}}</ref>
			People can be exposed to nitroglycerin in the workplace by breathing it in, skin absorption, swallowing it, or eye contact. The ] has set the legal limit (]) for nitroglycerin exposure in the workplace as 0.2&nbsp;ppm (2&nbsp;mg/m<sup>3</sup>) skin exposure over an 8-hour workday. The ] has set a ] of 0.1&nbsp;mg/m<sup>3</sup> skin exposure over an 8-hour workday. At levels of 75&nbsp;mg/m<sup>3</sup>, nitroglycerin is ].<ref>{{Cite web|publisher= CDC |work=NIOSH Pocket Guide to Chemical Hazards |title=Nitroglycerine|url = https://www.cdc.gov/niosh/npg/npgd0456.html|access-date = 2015-11-21}}</ref>
	For workers in nitroglycerin (NTG) manufacturing facilities, this can result in a "Monday morning headache" phenomenon for those who experience regular nitroglycerin exposure in the workplace leading to the development of NTG tolerance for the vasodilating effects. Over the weekend the workers lose the tolerance to NTG and when they are reexposed on Monday the prominent ] produces ], dizziness, and a headache.
	== See also ==		== See also ==
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	== References ==		== References ==
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	==External links==		==External links==
			{{Commonscat|Nitroglycerin}}
	* {{cite web|url=http://CPRR.org/Museum/Newspapers/Nitroglycerine.html | work=Central Pacific Railroad Photographic History Museum | title=Nitroglycerine! Terrible Explosion and Loss of Lives in San Francisco | accessdate=2005-03-23 }} - 1866 Newspaper article
			*{{cite web|url=http://CPRR.org/Museum/Newspapers/Nitroglycerine.html | work=Central Pacific Railroad Photographic History Museum | title=Nitroglycerine! Terrible Explosion and Loss of Lives in San Francisco | access-date=2005-03-23 }} – 1866 Newspaper article
	*
			*
	* Detailed and horrific stories of the historical use of nitroglycerin-filled ] to restart petroleum wells.
			*
			* Detailed and horrific stories of the historical use of nitroglycerin-filled ] to restart petroleum wells.
			* at '']'' (University of Nottingham)
			{{Nitric oxide signaling}}
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