Advancement of the third generation of antihistamines

Antihistamines are among the most commonly administered drugs in the world. They provide relief from the symptoms of allergies. The widespread need and use of antihistamines has fueled intense research and development for new and improved drugs. Antihistamines have evolved considerably since the first drugs with clinically useful antiallergic properties were introduced more than half a century ago. The elucidation of histamine receptor subtypes and of the molecular mechanisms that dictate drug potency, tissue distribution, and metabolism, as well as other advances in basic research, have driven the evolution of this class of therapeutics, Consequentially, the antihistamine drugs available to modern consumers, as well as many in development, are more efficacious, have reduced side effects, and are available in once-daily oral dosage form. This review will focus on the major developments in antihistamine therapy that have occurred in the latter half of this decade. The advancement of active isomers or metabolites of the nonsedating, second-generation of drugs to produce a third generation of superior agents will be discussed.