Chlorpheniramine is part of a series of antihistamines including pheniramine (Naphcon) and its halogenated derivatives and others including fluorpheniramine, dexchlorpheniramine (Polaramine), brompheniramine (Dimetapp), dexbrompheniramine (Drixoral), deschlorpheniramine, dipheniramine (also known as triprolidine with the trade name Actifed), and iodopheniramine. The halogenated alkylamine antihistamines all exhibit optical isomerism, and chlorpheniramine in the indicated products is racemic chlorpheniramine maleate, whereas dexchlorpheniramine (Polaramine) is the dextrorotary stereoisomer.