Products
Desloratadine is commercially available as 5 mg film-coated tablets and as a solution (Aerius, generics). It has been approved in many countries since 2001. The syrup was replaced in 2011 by a solution that is sugar- and dye-free. The concentration remains identical (0.5 mg/ml). The fixed combination with pseudoephedrine is not yet available in many countries. Generic versions of desloratadine went on sale in the fall of 2012. Desloratadine was developed starting from loratadine (Claritine, generics). Commercial reasons also played a role because Claritine’s patent expired. Desloratadine is a metabolite of loratadine and appears to be less prone to interactions and pharmacogenetic differences. Loratadine is itself a substrate of CYP3A4 and CYP2D6 and is almost completely biotransformed. Desloratadine, however, is not metabolically inert but is further hydroxylated and glucuronidated (see under Interactions).
Structure and properties
Desloratadine or descarboethoxyloratadine (C19H19ClN2, Mr = 310.82 g/mol) is a white powder that is sparingly soluble in water. It is the metabolite of loratadine, which is also formed when loratadine is ingested.
Effects
Desloratadine (ATC R06AX27) has antihistamine, antiallergic, and antiinflammatory properties. The effects are due to antagonism at histamine H1 receptors. Desloratadine causes less fatigue from than 1st generation antihistamines. It is not anticholinergic or cardiotoxic like astemizole or terfenadine.
Indication
For symptomatic treatment of allergic rhinitis (eg, hay fever) and urticaria (hives).
Dosage
According to the package insert. The usual dose for adults and adolescents 12 years and older is 5 mg regardless of meals. The drug may be administered once daily due to its long half-life of 27 hours. For children under 12 years of age, the solution is administered at a dosage appropriate for their age.
Contraindications
Desloratadine is contraindicated in hypersensitivity. For complete precautions, see the drug label.
Interactions
Desloratadine is biotransformed to the active metabolite 3-hydroxy-desloratadine and glucuronidated. The enzymes responsible are not yet known. There are poor metabolizers that cannot adequately form this metabolite. Ketoconazole, erythromycin, fluoxetine, and cimetidine may slightly increase plasma levels of desloratadine and 3-hydroxy-desloratadine, but this is not considered relevant and does not cause ECG changes.
Adverse effects
The most common adverse effects include dry mouth, fatigue, and headache. Very rare adverse effects include hallucinations, hyperactivity, seizures, dizziness, drowsiness, palpitations, lower abdominal pain, nausea, vomiting, indigestion, muscle pain, skin rash, and allergic symptoms.
