Pharmacodynamics<unk>  is a selective H1-antihistamine which functions as an inverse agonist at the histamine H1 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<unk>  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.<unk>  is metabolized to 3-hydroxydesloratadine in a three-step sequence in normal metabolizers. First, n-glucuronidation of<unk>  by UGT2B10; then, 3-hydroxylation of<unk>  N-glucuronide by CYP2C8; and finally, a non-enzymatic deconjugation of 3-hydroxydesloratadine N-glucuronide. Both<unk>  and 3-hydroxydesloratadine are eliminated via urine and feces with a half-life of 27 hours in normal metabolizers. 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.<unk>  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.<unk>  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. Pharmacogenomics 2% of Caucasian people and 18% of people from African descent are<unk>  poor metabolizers. In these people, the drug reaches threefold highest plasma concentrations six to seven hours after intake, and has a half-life of about 89 hours. However, the safety profile for these subjects is not worse than for extensive (normal) metabolizers.
Desloratadine
Loratadine
Rupatadine
Diquafosol
Olopatadine
Tiratricol
Terfenadine
Tralomethrin