Bromide

ChlorideIodideA bromide is a chemical compound containing a bromide ion or ligand. This is a bromine atom with an ionic charge of −1 (Br−); for example, in caesium bromide, caesium cations (Cs+) are electrically attracted to bromide anions (Br−) to form the electrically neutral ionic compound CsBr. The term 'bromide' can also refer to a bromine atom with an oxidation number of −1 in covalent compounds such as sulfur dibromide (SBr2). A bromide is a chemical compound containing a bromide ion or ligand. This is a bromine atom with an ionic charge of −1 (Br−); for example, in caesium bromide, caesium cations (Cs+) are electrically attracted to bromide anions (Br−) to form the electrically neutral ionic compound CsBr. The term 'bromide' can also refer to a bromine atom with an oxidation number of −1 in covalent compounds such as sulfur dibromide (SBr2). Bromide is present in typical seawater (35 PSU) with a concentration of around 65 mg/L, which is around 0.2% of all dissolved salts. Seafoods and deep sea plants generally have high levels of bromide, while foods derived from land have variable amounts. Bromargyryte - natural, crystalline silver bromide - is the most common bromide mineral currently known. It is still very rare. Beside silver, bromine is sometimes found in minerals combined with mercury and copper. One can test for a bromide ion by adding excess dilute HNO3 followed by dilute aqueous AgNO3 solution. The formation of creamy silver bromide precipitate confirms the existence of bromides. Bromide compounds, especially potassium bromide, were frequently used as sedatives in the 19th and early 20th century. Their use in over-the-counter sedatives and headache remedies (such as Bromo-Seltzer) in the United States extended to 1975, when bromides were withdrawn as ingredients, due to chronic toxicity. This use gave the word 'bromide' its colloquial connotation of a boring cliché, a bit of conventional wisdom overused as a calming phrase, or verbal sedative. The bromide ion is antiepileptic, and bromide salts are still used as such, particularly in veterinary medicine. Bromide ion is excreted by the kidneys. The half-life of bromide in the human body (12 days) is long compared with many pharmaceuticals, making dosing difficult to adjust (a new dose may require several months to reach equilibrium). Bromide ion concentrations in the cerebrospinal fluid are about 30% of those in blood, and are strongly influenced by the body's chloride intake and metabolism. Since bromide is still used in veterinary medicine (particularly to treat seizures in dogs) in the United States, veterinary diagnostic labs can routinely measure blood bromide levels. However, this is not a conventional test in human medicine in the U.S., since there are no FDA-approved uses for bromide, and (as noted) it is no longer available in over-the-counter sedatives. Therapeutic bromide levels are measured in European countries like Germany, where bromide is still used therapeutically in human epilepsy. Chronic toxicity from bromide can result in bromism, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption. See potassium bromide. Lithium bromide was used as a sedative beginning in the early 1900s, but it fell into disfavor in the 1940s, possibly due to the rising popularity of safer and more efficient sedatives (specifically, barbiturates) and when some heart patients died after using a salt substitute (see lithium chloride). Like lithium carbonate and lithium chloride it was used as treatment for bipolar disorder.