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 an d use of antihistamines has fueled intense research and development for new and improved drugs. Antihistamines have evolved considerably since the fir st drugs with clinically useful antiallergic properties were introduced mor e than half a century ago. The elucidation of histamine receptor subtypes a nd of the molecular mechanisms that dictate drug potency, tissue distributi on, and metabolism, as well as other advances in basic research, have drive n the evolution of this class of therapeutics, Consequentially, the antihis tamine 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 i n antihistamine therapy that have occurred in the latter half of this decad e. The advancement of active isomers or metabolites of the nonsedating, sec ond-generation of drugs to produce a third generation of superior agents wi ll be discussed.