Brands, Medical Use, Clinical Data
Drug Category
Dosage Forms
Brands / Synonyms
Aerius; Alavert; Clarinex; Clarinex Reditabs; Clarinex-D; Claritin; Claritin Reditabs; Descarboethoxyloratadine; Descarboethoxyoratidine; Desloratadine [Usan]; Desloratidine; Loratadine
Indications
For the relief of symptoms of seasonal allergic rhinitis, pruritus, reduction in the number of hives in patients with chronic idiopathic urticaria.
Pharmacology
Desloratadine is a long-lasting antihistamine. Desloratadine is a 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, for example, 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 allergy. 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.
Mechanism of Action
Like other H1-blockers, Desloratadine competes with free histamine for binding at H1-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.
Absorption
Not Available
Toxicity
Not Available
Biotrnasformation / Drug Metabolism
Not Available
Contraindications
CLARINEX Tablets 5 mg are contraindicated in patients who are hypersensitive to this medication or to
any of its ingredients, or to loratadine.
Drug Interactions
In two controlled crossover clinical pharmacology studies in healthy male (n=12 in each study) a nd
female (n=12 in each study) volunteers, desloratadine 7.5 mg (1.5 times the daily dose) once daily was coadministered
with erythromycin 500 mg every 8 hours or ketoconazole 200 mg every 12 hours for 10 days. In three separate
controlled, parallel group clinical pharmacology studies, desloratadine at the clinical dose of 5 mg has been
coadministered with azithromycin 500 mg followed by 250 mg once daily for 4 days (n=18) or with fluoxetine 20 mg once
daily for 7 days after a 23 day pretreatment period with fluoxetine (n=18) or with cimetidine 600 mg every 12 hours
for 14 days (n=18) under steady state conditions to normal healthy male and female volunteers. Although increased
plasma concentrations (C max and AUC 0-24 hrs) of desloratadine and 3-hydroxydesloratadine were observed ,
there were no clinically relevant changes in the safety profile of desloratadine, as assessed by electrocardiographic
parameters (including the corrected QT interval), clinical laboratory tests, vital signs, and adverse events.
Table 1
Changes in Desloratadine and 3-Hydroxydesloratadine Pharmacokinetics in Healthy Male and Female Volunteers |
|
Desloratadine |
3-Hydroxydesloratadine |
|
C max |
AUC
0-24 hrs |
C max |
AUC
0-24 hrs |
Erythromycin
|
(500 mg Q8h)
|
+24% |
+14% |
+43% |
+40% |
Ketoconazole
|
(200 mg Q12h)
|
+45% |
+39% |
+43% |
+72% |
Azithromycin
|
(500 mg day 1,
250 mg QD × 4 days)
|
+15% |
+5% |
+15% |
+4% |
Fluoxetine
|
(20 mg QD)
|
+15% |
+0% |
+17% |
+13% |
Cimetidine
|
(600 mg Q12h)
|
+12% |
+19% |
-11% |
-3% |
|