Brompheniramine

Brompheniramine (Bromfed, Dimetapp, Bromfenex, Dimetane, BPN, Lodrane), commonly marketed as its salt brompheniramine maleate is an antihistamine drug of the propylamine (alkylamine) class. It is readily available over the counter and is indicated for the treatment of the symptoms of the common cold and allergic rhinitis, such as runny nose, itchy eyes, watery eyes, and sneezing. It is a first-generation antihistamine.

Brompheniramine is part of a series of antihistamines including pheniramine (Naphcon) and its halogenated derivatives and others including fluorpheniramine, chlorpheniramine, dexchlorpheniramine (Polaramine), deschlorpheniramine, dipheniramine (also known as triprolidine with the trade name Actifed), and iodopheniramine.

The halogenated alkylamine antihistamines all exhibit optical isomerism and brompheniramine products contain racemic brompheniramine maleate whereas dexbrompheniramine (Drixoral) is the dextrorotary (right-handed) stereoisomer.

Brompheniramine has antidepressant properties, inhibiting reuptake of the neurotransmitter serotonin. Based on this knowledge, Arvid Carlsson and his colleagues, working at the Swedish company Astra AB, were able to derive the first marketed selective serotonin reuptake inhibitor, zimelidine, from brompheniramine.

Like other agents of this type, brompheniramine also has analgesic-sparing (potentiating) effects on opioid analgesics, commonly reducing codeine, dihydrocodeine, and hydrocodone requirements by 10 to 35 percent.

Pharmacology
Brompheniramine works by acting as an antagonist of histamine H1 receptors. It also functions as a moderately effective anticholinergic agent, and is likely an antimuscarinic agent similar to other common antihistamines such as diphenhydramine.

Brompheniramine is metabolised by cytochrome P450s.

The halogenated alkylamine antihistamines all exhibit optic isomerism and brompheniramine products contain racaemic brompheniramine maleate whereas dexbrompheniramine (Drixoral) is the dextrorotary (right-handed) stereoisomer.

Side effects
Its effects on the cholinergic system may include side-effects such as drowsiness, sedation, dry mouth, dry throat, blurred vision, and increased heart rate.

Chemistry
Brompheniramine, 3-(p-bromophenyl)-3-(2-pyridyl)propyldimethylamine, is an analog of chlorpheniramine. The only difference is that the chlorine atom in the benzene ring is replaced with a bromine atom. It is also synthesized in an analogous manner.


 * L.A. Walter, (1962).
 * L.A. Walter, (1962).