Potassium bromide

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Potassium bromide
Potassium bromide.jpg
Potassium-bromide-3D-ionic.png
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.937 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • TS7650000
UNII
  • InChI=1S/BrH.K/h1H;/q;+1/p-1 X mark.svgN
    Key: IOLCXVTUBQKXJR-UHFFFAOYSA-M X mark.svgN
  • InChI=1/BrH.K/h1H;/q;+1/p-1
    Key: IOLCXVTUBQKXJR-REWHXWOFAT
  • [K+].[Br-]
Properties
KBr
Molar mass 119.002 g/mol
Appearancewhite solid
Odor odorless
Density 2.74 g/cm3
Melting point 734 °C (1,353 °F; 1,007 K)
Boiling point 1,435 °C (2,615 °F; 1,708 K)
535 g/L (0 °C)
678 g/L (25 °C)
1020 g/L (100 °C)
Solubility very slightly soluble in diethyl ether
Solubility in glycerol 217 g/L
Solubility in ethanol 47.6 g/L (80 °C)
49.1·10−6 cm3/mol
1.559
Structure
Sodium chloride(Face-centered cubic)
octahedral
10.41 D (gas)
Pharmacology
QN03AX91 ( WHO )
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H319
P280, P305+P351+P338, P337+P313 [1]
NFPA 704 (fire diamond)
[2]
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Lethal dose or concentration (LD, LC):
3070 mg/kg (oral, rat) [3]
Related compounds
Other anions
Potassium fluoride
Potassium chloride
Potassium iodide
Other cations
Lithium bromide
Sodium bromide
Rubidium bromide
Caesium bromide
Francium bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium bromide (K Br) is a 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 ]

Chemical properties

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:

Aqueous bromide Br also forms complexes when reacted with some metal halides such as copper(II) bromide:

Preparation

A traditional method for the manufacture of KBr is the reaction of potassium carbonate with an iron(III, II) bromide, Fe3Br8, made by treating scrap iron under water with excess bromine: [4]

Applications

Medical and veterinary

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). The pink color of the solution is artificial; pure potassium bromide solutions are colorless Potassium bromide veterinary.JPG
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). 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 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. [6] 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). [6] By the beginning of the 20th century the generic word had become so widely associated with being sedate that bromide came to mean a dull, sedate person or a boring platitude uttered by such a person. [7]

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. [8] [9]

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. [10] 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. [5] Use of bromide in cats is limited because it carries a substantial risk of causing lung inflammation (pneumonitis) in them. 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. [11] 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, [6] 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. [6]

The therapeutic index (ratio of effectiveness to toxicity) for bromide is small. As with other antiepileptics, sometimes even therapeutic doses (3 to 5 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:

Optics

Potassium bromide is transparent from the near ultraviolet to long-wave infrared wavelengths (0.25-25 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. [12]

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 µm.

Photography

In addition to manufacture of silver bromide, potassium bromide is used as a restrainer in black and white developer formulas. It improves differentiation between exposed and unexposed crystals of silver halide, and thus reduces fog. [13]

Related Research Articles

<span class="mw-page-title-main">Bromine</span> Chemical element, symbol Br and atomic number 35

Bromine is a chemical element; it has symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard, its name was derived from the Ancient Greek βρῶμος (bromos) meaning "stench", referring to its sharp and pungent smell.

<span class="mw-page-title-main">Phenytoin</span> Anti-seizure medication

Phenytoin (PHT), sold under the brand name Dilantin among others, is an anti-seizure medication. It is useful for the prevention of tonic-clonic seizures and focal seizures, but not absence seizures. The intravenous form, fosphenytoin, is used for status epilepticus that does not improve with benzodiazepines. It may also be used for certain heart arrhythmias or neuropathic pain. It can be taken intravenously or by mouth. The intravenous form generally begins working within 30 minutes and is effective for roughly 24 hours. Blood levels can be measured to determine the proper dose.

Anticonvulsants are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder and borderline personality disorder, since many seem to act as mood stabilizers, and for the treatment of neuropathic pain. Anticonvulsants suppress the excessive rapid firing of neurons during seizures. Anticonvulsants also prevent the spread of the seizure within the brain.

<span class="mw-page-title-main">Oxcarbazepine</span> Anticonvulsant medication

Oxcarbazepine, sold under the brand name Trileptal among others, is a medication used to treat epilepsy. For epilepsy it is used for both focal seizures and generalized seizures. It has been used both alone and as add-on therapy in people with bipolar disorder who have had no success with other treatments. It is taken by mouth.

<span class="mw-page-title-main">Clonazepam</span> Benzodiazepine medication

Clonazepam, sold under the brand names Klonopin and Rivotril, is a medication used to prevent and treat anxiety disorders, seizures, bipolar mania, agitation associated with psychosis, OCD and akathisia. It is a long-acting tranquilizer of the benzodiazepine class. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. It is typically taken by mouth but is also used intravenously. Effects begin within one hour and last between eight and twelve hours in adults.

<span class="mw-page-title-main">Tetraethylammonium</span> Polyatomic ion (N(C₂H₅)₄, charge +1)

Tetraethylammonium (TEA) is a quaternary ammonium cation with the chemical formula [Et4N]+, consisting of four ethyl groups attached to a central nitrogen atom. It is a counterion used in the research laboratory to prepare lipophilic salts of inorganic anions. It is used similarly to tetrabutylammonium, the difference being that its salts are less lipophilic, more easily crystallized and more toxic.

<span class="mw-page-title-main">Silver bromide</span> Chemical compound

Silver bromide (AgBr) is a soft, pale-yellow, water-insoluble salt well known for its unusual sensitivity to light. This property has allowed silver halides to become the basis of modern photographic materials. AgBr is widely used in photographic films and is believed by some to have been used for making the Shroud of Turin. The salt can be found naturally as the mineral bromargyrite.

<span class="mw-page-title-main">Silver chloride</span> Chemical compound with the formula AgCl

Silver chloride is an inorganic chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water and its sensitivity to light. Upon illumination or heating, silver chloride converts to silver, which is signaled by grey to black or purplish coloration in some samples. AgCl occurs naturally as the mineral chlorargyrite.

<span class="mw-page-title-main">Sodium bromide</span> Inorganic salt: NaBr

Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion and has many applications.

<span class="mw-page-title-main">Phenobarbital</span> Medication of the barbiturate type

Phenobarbital, also known as phenobarbitone or phenobarb, sold under the brand name Luminal among others, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of epilepsy in developing countries. In the developed world, it is commonly used to treat seizures in young children, while other medications are generally used in older children and adults. In developed countries it is used for veterinary purposes. It may be used intravenously, injected into a muscle, or taken by mouth. The injectable form may be used to treat status epilepticus. Phenobarbital is occasionally used to treat trouble sleeping, anxiety, and drug withdrawal and to help with surgery. It usually begins working within five minutes when used intravenously and half an hour when administered by mouth. Its effects last for between four hours and two days.

A silver chloride electrode is a type of reference electrode, commonly used in electrochemical measurements. For environmental reasons it has widely replaced the saturated calomel electrode. For example, it is usually the internal reference electrode in pH meters and it is often used as reference in reduction potential measurements. As an example of the latter, the silver chloride electrode is the most commonly used reference electrode for testing cathodic protection corrosion control systems in sea water environments.

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<span class="mw-page-title-main">Clorazepate</span> Benzodiazepine medication

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In electrochemistry, cell notation or cell representation is a shorthand method of expressing a reaction in an electrochemical cell.

<span class="mw-page-title-main">Seletracetam</span> Chemical compound

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<span class="mw-page-title-main">GABA receptor agonist</span> Category of drug

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<span class="mw-page-title-main">Lacosamide</span> Anticonvulsant and analgesic medication

Lacosamide, sold under the brand name Vimpat among others, is a medication used for the treatment of partial-onset seizures and primary generalized tonic-clonic seizures. It is used by mouth or intravenously.

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Retigabine (INN) or ezogabine (USAN) is an anticonvulsant used as an adjunctive treatment for partial epilepsies in treatment-experienced adult patients. The drug was developed by Valeant Pharmaceuticals and GlaxoSmithKline. It was approved by the European Medicines Agency under the trade name Trobalt on March 28, 2011, and by the United States Food and Drug Administration (FDA), under the trade name Potiga, on June 10, 2011. Production was discontinued in June 2017.

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References

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