Molecule

Drug Groups

approved; investigational

Description

Desloratadine is a second generation, tricyclic antihistamine that which has a selective and peripheral H1-antagonist action. It is the active descarboethoxy metabolite of loratidine (a second generation histamine). Desloratidine has a long-lasting effect and does not cause drowsiness because it does not readily enter the central nervous system.

Indication

For the relief of symptoms of seasonal allergic rhinitis, perennial (non-seasonal) allergic rhinitis. Desloratidine is also used for the sympomatic treatment of pruritus and urticaria (hives) associated with chronic idiopathic urticaria.

Pharmacology

Desloratadine is a long-acting second-generation H₁-receptor antagonist which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, such as the swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergies. Desloratadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Desloratadine does not enter the brain from the blood and, therefore, does not cause drowsiness.

Affected Organisms

Half Life

50 hours

Protein Binding

82-87%

Elimination

Desloratadine (a major metabolite of loratadine) is extensively metabolized to 3-hydroxydesloratadine, an active metabolite, which is subsequently glucuronidated. Approximately 87% of a 14C-desloratadine dose was equally recovered in urine and feces.

References

External Links