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Clinical data | |
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Trade names | Clarinex, Aerius, Allex, others [1] |
Other names | descarboethoxyloratadine [2] |
AHFS/Drugs.com | Monograph |
MedlinePlus | a602002 |
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Routes of administration | By mouth |
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Pharmacokinetic data | |
Bioavailability | Rapidly absorbed |
Protein binding | 83 to 87% |
Metabolism | UGT2B10, CYP2C8 |
Metabolites | 3-Hydroxydesloratadine |
Onset of action | within 1 hour [7] |
Elimination half-life | 27 hours, [7] 33.7 hours in elderly patients [3] |
Duration of action | up to 24 hours [7] |
Excretion | 40% as conjugated metabolites into urine Similar amount into the feces |
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ECHA InfoCard | 100.166.554 |
Chemical and physical data | |
Formula | C19H19ClN2 |
Molar mass | 310.83 g·mol−1 |
3D model (JSmol) | |
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Desloratadine sold under the brand name Clarinex among others, is a tricyclic H1 inverse agonist that is used to treat allergies. It is an active metabolite of loratadine. [7]
It was patented in 1984 and came into medical use in 2001. [8] It was brought to the market in the US by Schering Corporation, later named Schering-Plough. [3]
Desloratadine is used to treat allergic rhinitis, nasal congestion and chronic idiopathic urticaria (hives). [9] It is the major metabolite of loratadine and the two drugs are similar in safety and effectiveness. [9] Desloratadine is available in many dosage forms and under many brand names worldwide. [10]
An emerging indication for desloratadine is in the treatment of acne, as an inexpensive adjuvant to isotretinoin and possibly as maintenance therapy or monotherapy. [11] [12]
The most common side-effects are fatigue (1.2% [13] ), dry mouth (3% [13] ), and headache (0.6% [13] ). [9]
Co-administration with erythromycin, ketoconazole, azithromycin, fluoxetine, or cimetidine resulted in elevated blood plasma concentrations of desloratadine and its metabolite 3-hydroxydesloratadine in studies. However, no clinically relevant changes were observed. [3] [14]
Desloratadine is a selective H1-antihistamine which functions as an inverse agonist at the histamine H1 receptor. [15]
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. [16]
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. [14]
Desloratadine is metabolized to 3-hydroxydesloratadine in a three-step sequence in normal metabolizers. First, N-glucuronidation of desloratadine by UGT2B10; then, 3-hydroxylation of desloratadine N-glucuronide by CYP2C8; and finally, a non-enzymatic deconjugation of 3-hydroxydesloratadine N-glucuronide. [17] [18] Both desloratadine and 3-hydroxydesloratadine are eliminated via urine and feces with a half-life of 27 hours in normal metabolizers. [14] [19]
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. [20]
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. [18]
2% of Caucasian people and 18% of people from African descent are desloratadine poor metabolizers. In these people, the drug reaches threefold higher plasma concentrations at seven hours after intake, and it has a half-life of 89 hours (compared to a 27-hour half-life in normal metabolizers). Adverse effects were reported at similar rates in poor metabolizers, suggesting that it is not clinically relevant. [14] [19]
loratadine is metabolized to descarboethoxyloratadine predominantly by cytochrome P450 3A4 (CYP3A4) and, to a lesser extent, by cytochrome P450 2D6 (CYP2D6).