Potassium bromide (KBr) is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries. Its action is due to the bromide ion (sodium bromide is equally effective). Potassium bromide is presently used as veterinary drug, as an antiepileptic medication for dogs and cats. It is a white crystalline powder, soluble in water. In a dilute aqueous solution, potassium bromide tastes sweet, at higher concentration it tastes bitter, and when most concentrated it tastes salty to humans (these effects are due mainly to potassium ion; sodium bromide merely tastes salty at all concentrations). In high concentration potassium bromide strongly irritates the gastric mucous membrane, leading to nausea and sometimes vomiting (again this effect is typical of all soluble potassium salts).
Potassium bromide is used to treat epilepsy in dogs, either as first-line treatment or in addition to phenobarbital when the seizures are not adequately controlled with phenobarbital alone. Use of bromide in cats is limited because it carries a substantial risk of causing lung inflammation (pneumonitis) in this species.
Potassium bromide is not approved by the US Food and Drug Administration (FDA) for use in humans to control seizures. In Germany it continues to be approved for use as an antiepileptic drug for humans, particularly children and adolescents. These indications include severe forms of generalized tonic-clonic seizures, early-childhood-related Grand-Mal-seizures, and also severe myoclonic seizures during childhood. Adults who have reacted positively to the drug during childhood/adolescence may continue treatment. KBr is sold under the brand name Dibro-Be mono (RX-only). When used for proper indications it shows promising results. The drug has almost complete bioavailability and an extremely long half-life of 6 weeks. One tablet contains 850 mg of potassium bromide. Potassium bromide is not known to interfere with the absorption or excretion of any other anticonvulsant.
The therapeutic index is very small for bromide. As with other antiepileptics, sometimes even therapeutic doses give rise to intoxication. Often indistinguishable from 'expected' side-effects, these include:
In infrared spectroscopy, samples are analyzed by grinding with KBr powder, and pressing into a disc. Alternatively, the samples may be analyzed as a liquid film (neat, as a solution, or in a mull with Nujol) between two polished KBr discs.