<!-- Definition and medical uses -->

Desloratadine, sold under the brand name Aerius among others, is a tricyclic H<sub>1</sub> inverse agonist that is used to treat allergies. It is the major active metabolite of loratadine.

<!-- Society and culture -->

It was patented in 1984 and came into medical use in 2001. It was brought to the market in the US by Schering Corporation, later named Schering-Plough. It is the major metabolite of loratadine and the two drugs are similar in safety and effectiveness.

An emerging indication for desloratadine is in the treatment of acne, as an inexpensive adjuvant to isotretinoin and possibly as maintenance therapy or monotherapy.

Side effects

The most common side effects are fatigue (1.2%), dry mouth (3%), and headache (0.6%).

Pharmacology

Pharmacodynamics

Desloratadine is a selective H<sub>1</sub>-antihistamine which functions as an inverse agonist at the histamine H<sub>1</sub> receptor.

At very high doses, is also an antagonist at various subtypes of the muscarinic acetylcholine receptors. This effect is not relevant for the drug's action at therapeutic doses.

Pharmacokinetics

Desloratadine is well absorbed from the gut and reaches highest blood plasma concentrations after about three hours. In the bloodstream, 83 to 87% of the substance are bound to plasma proteins. Both desloratadine and 3-hydroxydesloratadine are eliminated via urine and feces with a half-life of 27 hours in normal metabolizers.

class=skin-invert-image|thumb|left|3-Hydroxydesloratadine is the main [[metabolite.]]

It exhibits only peripheral activity since it does not readily cross the blood–brain barrier; hence, it does not normally cause drowsiness because it does not readily enter the central nervous system.

Desloratadine does not have a strong effect on a number of tested enzymes in the cytochrome P450 system. It was found to weakly inhibit CYP2B6, CYP2D6, and CYP3A4/CYP3A5, and not to inhibit CYP1A2, CYP2C8, CYP2C9, or CYP2C19. Desloratadine was found to be a potent and relatively selective inhibitor of UGT2B10, a weak to moderate inhibitor of UGT2B17, UGT1A10, and UGT2B4, and not to inhibit UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B7, UGT2B15, UGT1A7, and UGT1A8.