Bromide ion (Br-)

Bromide is a halide anion that serves as an essential trace element and a historical pharmacological agent. It is a required cofactor for the enzyme peroxidasin, which catalyzes the formation of sulfilimine cross-links in collagen IV, a process vital for the structural integrity of basement membranes (McCall et al., 2014). In a clinical context, bromide salts were the first effective treatments for epilepsy and were widely used as sedatives in the 19th century. The ion's therapeutic effect stems from its ability to mimic chloride; it passes through GABA-gated chloride channels more readily than chloride, resulting in neuronal hyperpolarization and an increased seizure threshold (StatPearls). While largely replaced by modern anticonvulsants in humans, it remains a common treatment for canine epilepsy. Chronic use can lead to bromism, a toxic condition characterized by neurological symptoms, psychiatric disturbances, and skin rashes known as bromoderma (NIH). Its long elimination half-life of approximately 12 days presents a significant therapeutic challenge in maintaining stable concentrations (PubChem).

Other names

BromideBromide(1-)Bromine anion

Bromide acts as a chloride analog that competes with chloride for transport across neuronal membranes. It is transported into neurons via GABA-A receptor-associated chloride channels, where its higher permeability relative to chloride leads to enhanced hyperpolarization and reduced neuronal excitability (StatPearls). Additionally, bromide is an essential cofactor for the enzyme peroxidasin, which uses it to generate hypobromous acid to form sulfilimine bonds that cross-link collagen IV in basement membranes (McCall et al., 2014).