Potassium bromide: Difference between revisions

{{Short description|Ionic compound (KBr)}}

{{Use dmy dates|date=September 2021}}

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 413798711

| Name = Potassium bromide

| ImageFile = Potassium bromide.jpg

| ImageName = Potassium bromide

| ImageFile1 = Potassium-bromide-3D-ionic.png

| ImageSize1 =

| ImageName1 = Potassium bromide

|Section1={{Chembox Identifiers

| CASNo = 7758-02-3

| CASNo_Ref = {{cascite|correct|CAS}}

| UNII_Ref = {{fdacite|changed|FDA}}

| UNII = OSD78555ZM

| PubChem = 253877

| ChEBI = 32030

| ChEBI_Ref = {{ebicite|changed|EBI}}

| ChEMBL_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 1644030

| RTECS = TS7650000

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 22854

| SMILES = [K+].[Br-]

| InChI = 1/BrH.K/h1H;/q;+1/p-1

| InChIKey = IOLCXVTUBQKXJR-REWHXWOFAT

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/BrH.K/h1H;/q;+1/p-1

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = IOLCXVTUBQKXJR-UHFFFAOYSA-M

|Section2={{Chembox Properties

| Formula = KBr

| MolarMass = 119.002 g/mol

| Appearance = white solid

| Odor = odorless

| Density = 2.74 g/cm³

| Solubility = 535 g/L (0&nbsp;°C) <br> 678 g/L (25&nbsp;°C) <br> 1020 g/L (100&nbsp;°C)

| Solvent1 = glycerol

| Solubility1 = 217 g/L

| Solvent2 = ethanol

| Solubility2 = 47.6 g/L (80&nbsp;°C)

| SolubleOther = very slightly soluble in [[diethyl ether]]

| MeltingPtC = 734

| BoilingPtC = 1435

| RefractIndex = 1.559

| MagSus = &minus;49.1·10⁻⁶ cm³/mol

|Section3={{Chembox Structure

| Coordination = [[octahedral]]

| CrystalStruct = [[Sodium chloride]](Face-centered cubic)

| Dipole = 10.41 [[Debye|D]] (''gas'')

| Section6 = {{Chembox Pharmacology

| ATCvet = yes

| ATCCode_prefix = N03

| ATCCode_suffix = AX91

}}

|Section7={{Chembox Hazards

| NFPA-H = 1

| NFPA-F = 0

| NFPA-R = 0

| NFPA_ref = <ref>{{cite web|url=http://labchem.com/tools/msds/msds/LC18781.pdf|title=Labchem MSDS, sec. 16, p. 6|access-date=27 November 2018|archive-date=18 December 2021|archive-url=https://web.archive.org/web/20211218020141/http://labchem.com/tools/msds/msds/LC18781.pdf|url-status=live}}</ref>

| ExternalSDS =

| GHSPictograms = {{GHS07}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|319}}

| PPhrases = {{P-phrases|280|305+351+338|337+313}}<ref>{{cite web | url=https://www.sigmaaldrich.com/catalog/product/sigald/221864?lang=en&region=US | title=Potassium bromide 221864 | access-date=1 October 2018 | archive-date=3 June 2021 | archive-url=https://web.archive.org/web/20210603013427/https://www.sigmaaldrich.com/catalog/product/sigald/221864?lang=en&region=US | url-status=live }}</ref>

| LD50 = 3070 mg/kg (oral, rat)<ref>{{cite web|url=https://chem.nlm.nih.gov/chemidplus/rn/7758-02-3|title=ChemIDplus&nbsp;— Potassium bromide|work=chem.sis.nlm.nih.gov|access-date=11 August 2014|archive-date=12 August 2014|archive-url=https://web.archive.org/web/20140812202300/https://chem.nlm.nih.gov/chemidplus/rn/7758-02-3|url-status=live}}</ref>

|Section8={{Chembox Related

| OtherAnions = [[Potassium fluoride]]<br />[[Potassium chloride]]<br />[[Potassium iodide]]

| OtherCations = [[Lithium bromide]]<br />[[Sodium bromide]]<br />[[Rubidium bromide]]<br />[[Caesium bromide]]<br/>[[Francium bromide]]

'''Potassium bromide''' ([[Potassium|K]][[Bromine|Br]]) is a [[salt (chemistry)|salt]], widely used as an [[anticonvulsant]] and a [[sedative]] in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to the [[bromide]] ion ([[sodium bromide]] is equally effective). Potassium bromide is used as a veterinary drug, in antiepileptic medication for dogs.

Under standard conditions, potassium bromide is a white crystalline powder. It is freely soluble in water; it is not soluble in [[acetonitrile]]. In a dilute aqueous solution, potassium bromide tastes sweet, at higher concentrations it tastes bitter, and tastes salty when the concentration is even higher. These effects are mainly due to the properties of the potassium ion—sodium bromide tastes salty at any concentration. In high concentration, potassium bromide strongly irritates the gastric mucous membrane, causing nausea and sometimes vomiting (a typical effect of all soluble potassium salts).{{Citation needed|date=October 2020}}

Potassium bromide, a typical [[ionic salt]], is fully dissociated and near [[pH]] 7 in [[aqueous]] solution. It serves as a source of bromide ions. This reaction is important for the manufacture of [[silver bromide]] for [[photographic film]]:

:<chem>KBr_{(aq)}{} + AgNO3_{(aq)} -> AgBr_{(s)}{} + KNO3_{(aq)}</chem>

Aqueous bromide {{chem2|Br-}} also forms [[complex (chemistry)|complexes]] when reacted with some metal halides such as [[copper(II) bromide]]:

:<chem>2 KBr_{(aq)}{} + CuBr2_{(aq)} -> K2[CuBr4]_{(aq)}</chem>

A traditional method for the manufacture of KBr is the reaction of [[potassium carbonate]] with an iron([[Iron(III) bromide|III]], [[Iron(II) bromide|II]]) bromide, {{chem2|Fe3Br8}}, made by treating scrap iron under water with excess [[bromine]]:<ref>{{cite web|url=http://www.tititudorancea.com/z/potassium_bromide.htm|title=Potassium bromide|work=The Titi Tudorancea Bulletin|access-date=9 December 2014|archive-date=10 December 2015|archive-url=https://web.archive.org/web/20151210202142/https://www.tititudorancea.com/z/potassium_bromide.htm|url-status=live}}</ref>

:<chem>4 K2CO3 + Fe3Br8 -> 8 KBr + Fe3O4 + 4 CO2</chem>

===Medical and veterinary===

[[File:Potassium bromide veterinary.JPG|thumb|left|200 px|A bottle of PRN Pharmaceutical Company (Pensacola, FL) '''K•BroVet''' veterinary pharmaceutical potassium bromide oral solution (250 mg/mL). The product is intended to be used in dogs, primarily as an [[antiepileptic]] (to stop seizures).<ref name="dailymed"/> The pink color of the solution is artificial; pure potassium bromide solutions are colorless]]

The anticonvulsant properties of potassium bromide were first noted by Sir Charles Locock at a meeting of the [[Medical and Chirurgical Society of London|Royal Medical and Chirurgical Society]] in 1857. Bromide can be regarded as the first effective medication for [[epilepsy]]. At the time, it was commonly thought that epilepsy was caused by masturbation.<ref name="Goodman1970">{{cite book | last1 =Goodman | last2 =Gilman | edition =4th | chapter =Chapter 10: Hypnotics and Sedatives | pages =121–2 | title = The Pharmacological Basis of Therapeutics | publisher = MacMillan | year =1970 | location = London}}</ref> Locock noted that bromide calmed sexual excitement and thought this was responsible for his success in treating seizures. In the latter half of the 19th century, potassium bromide was used for the calming of seizure and nervous disorders on an enormous scale, with the use by single hospitals being as much as several tons a year (the dose for a given person being a few grams per day).<ref name="Goodman1970"/> By the beginning of the 20th century the generic word had become so widely associated with being sedate that [[Bromide (language)|bromide]] came to mean a dull, sedate person or a boring [[platitude]] uttered by such a person.<ref>{{cite book |last=Metcalf |first=Alan A.|title=Predicting New Words – The Secrets of Their Success |url=https://archive.org/details/predictingnewwor00alla |url-access=registration |access-date=27 August 2017 |year=2004 |publisher=Houghton Mifflin Harcourt |location=Boston |isbn=978-0-618-13006-1 |pages=[https://archive.org/details/predictingnewwor00alla/page/36 36]–42}}</ref>

There was not a better epilepsy drug until [[phenobarbital]] in 1912. The [[British Army]] has historically been claimed to lace soldiers' [[tea]] with bromide to quell sexual arousal and in the Victorian era prisoners in England were compulsorily dosed with the chemical.<ref>{{Cite web|url=https://www.jonkers.co.uk/rare-book/9472/de-profundis/oscar-wilde|archiveurl=https://web.archive.org/web/20230619195646/https://www.jonkers.co.uk/rare-book/9472/de-profundis/oscar-wilde|url-status=dead|title=De Profundis by WILDE, Oscar - Jonkers Rare Books|archivedate=19 June 2023|website=www.jonkers.co.uk}}</ref><ref>{{Cite web|url=https://www.podchaser.com/podcasts/the-rest-is-history-1544851/episodes/342-the-trials-of-oscar-wilde-176357163|archiveurl=https://web.archive.org/web/20230619195645/https://www.podchaser.com/podcasts/the-rest-is-history-1544851/episodes/342-the-trials-of-oscar-wilde-176357163|url-status=dead|title=The Trials of Oscar Wilde: Downfall and Prison by The Rest Is History &#124; Podchaser|archivedate=19 June 2023}}</ref>

Bromide compounds, especially [[sodium bromide]], remained in over-the-counter sedatives and headache remedies (such as the original formulation of [[Bromo-Seltzer]]) in the US until 1975, when bromides were outlawed in all over-the-counter medicines, due to chronic toxicity.<ref>{{Cite book | url =https://archive.org/details/greatamericanfr03adamgoog | quote =The Great American Fraud. | title = The Great American Fraud | publisher =Press of the American Medical Association | last1 =Adams | first1 =Samuel Hopkins | year =1905 }}</ref> Bromide's exceedingly long half life in the body made it difficult to dose without side effects. Medical use of bromides in the US was discontinued at this time, as many better and shorter-acting sedatives were known by then.

Potassium bromide is used in veterinary medicine to treat [[epilepsy in dogs]], either as first-line treatment or in addition to phenobarbital, when seizures are not adequately controlled with phenobarbital alone.<ref name="dailymed">{{DailyMed|a2462704-1d66-4d53-8ecd-22f72439cdb6|K-BROVET 250- potassium bromide tablet, chewable}}</ref> Use of bromide in cats is limited because it carries a substantial risk of causing lung inflammation (pneumonitis) in them. Why bromides should cause such inflammation in cats, but not in dogs is not clear.<ref name=”Bertolani_2012”>{{cite journal | vauthors = Bertolani C, Hernandez J, Gomes E, Cauzinille L, Poujade A, Gabriel A| title = Bromide-associated lower airway disease: a retrospective study of seven cats| journal = J Feline Med Surg| volume = 14 | issue = 8 | pages = 591-597| date = 2012 | doi = 10.1177/1098612X12445069|url= https://journals.sagepub.com/doi/10.1177/1098612X12445069?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed |archive-url= |archive-date=|PMID = 22496147 | PMC= 11104190}}</ref>

The use of bromide as a treatment drug for animals means that veterinary medical diagnostic laboratories are able as a matter of routine to measure serum levels of bromide on order of a veterinarian, whereas human medical diagnostic labs in the US do not measure bromide as a routine test.

Potassium bromide is not approved by the US [[Food and Drug Administration]] (FDA) for use in humans to control seizures. In Germany, it is still approved as an antiepileptic drug for humans, particularly children and adolescents.<ref>{{Cite web |url=http://www.apotheken-umschau.de/Medikamente/Beipackzettel/DIBRO-BE-MONO-850mg-4648235.html |title=German leaflet |access-date=13 November 2016 |archive-date=26 March 2017 |archive-url=https://web.archive.org/web/20170326050329/http://www.apotheken-umschau.de/Medikamente/Beipackzettel/DIBRO-BE-MONO-850mg-4648235.html |url-status=dead }}</ref> These indications include severe forms of generalized tonic-clonic seizures, early-childhood-related tonic–clonic seizures, and also severe myoclonic seizures during childhood. Adults who have reacted positively to the drug during childhood/adolescence may continue treatment. Potassium bromide tablets are sold under the brand name ''Dibro-Be mono'' (Rx-only). The drug has almost complete bioavailability, but the bromide ion has a relatively long half life of 12 days in the blood,<ref name="Goodman1970"/> making bromide salts difficult to adjust and dose. Bromide is not known to interfere with the absorption or excretion of any other anticonvulsant, though it does have strong interactions with chloride in the body, the normal body uptake and excretion of which strongly influences bromide's excretion.<ref name="Goodman1970"/>

The therapeutic index (ratio of effectiveness to toxicity) for bromide is small. As with other antiepileptics, sometimes even therapeutic doses (3 to 5&nbsp;grams per day, taking 6 to 8 weeks to reach stable levels) may give rise to intoxication. Often indistinguishable from 'expected' side-effects, these include:

**depression,

**[[lethargy]], [[somnolence]] (from daytime sleepiness to [[coma]])

**loss of appetite and [[cachexia]], nausea/emesis with [[exicosis]] (loss of body fluid)

**loss of [[reflexes]] or pathologic reflexes

**[[clonic seizures]]

**[[tremor]]

**[[ataxia]]

**loss of neural sensitivity

**[[paresis]]

**[[cerebral edema]] with associated headache and [[papilledema]] of the eyes

**[[delirium]]: confusion, abnormal speech, loss of concentration and memory, aggressiveness

**[[psychosis]]

*Acne-form dermatitis and other forms of skin disease may also be seen, as well as mucous hypersecretion in the lungs. Asthma and rhinitis may worsen. Rarely, tongue disorder, [[aphthous stomatitis]], [[halitosis|bad breath]], and [[constipation]] occur.

Potassium bromide is transparent from the near [[ultraviolet]] to long-wave [[infrared]] [[wavelength]]s (0.25-25&nbsp;μm) and has no significant [[optical absorption]] lines in its high transmission region.

It is used widely as infrared optical windows and components for general spectroscopy because of its wide spectral range. In [[infrared spectroscopy]], samples are analyzed by grinding with powdered potassium bromide and pressing into a disc. Alternatively, samples may be analyzed as a liquid film (neat, as a solution, or in a mull with [[Nujol]]) between two polished potassium bromide discs.<ref>{{cite web | url = http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/InfraRed/infrared.htm | archive-url = https://web.archive.org/web/20071027110406/http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/InfraRed/infrared.htm | archive-date = 2007-10-27 | work = VirtualText of Organic Chemistry | title = Infrared Spectroscopy | author = Reusch, W. | access-date = 18 December 2007}}</ref>

Due to its high solubility and [[hygroscopic]] nature it must be kept in a dry environment. The [[refractive index]] is about 1.55 at 1.0&nbsp;μm.

In addition to manufacture of silver bromide, potassium bromide is used as a restrainer in [[black and white]] [[Photographic developer|developer]] formulas. It improves differentiation between exposed and unexposed crystals of silver halide, and thus reduces fog.<ref>{{cite book

| last1 = Anchell | first1 = Stephen

| last2 = Troop | first2 = Bill

| title = The Film Developing Cookbook

| publisher = Focal Press

| location = Boston

| year = 1998

| page = 28}}</ref>

{{reflist}}

{{Commons category|Potassium bromide}}

* [https://web.archive.org/web/20080415185010/http://www.vetmed.auburn.edu/index.pl/potassium_bromide Veterinary use note at Auburn University]

{{Sedatives}}

{{GABAAR PAMs}}

{{bromides}}

{{Authority control}}

[[Category:GABAA receptor positive allosteric modulators]]

[[Category:Alkali metal bromides]]

[[Category:Rock salt crystal structure]]