Desloratadine

Desloratadine is a second-generation tricyclic antihistamine that has a selective and peripheral H1-antagonistic effect. It is the active descarboethoxy metabolite of loratidine. It is used for the treatment of allergic reactions. Desloratidine has a long-lasting effect and does not cause drowsiness because it does not cross the blood-brain barrier. It was patented in 1984 and has been used in medicine since 2001.

Pharmacodynamics

Like other H1 blockers, desloratadine competes with free histamine for binding to H1 receptors in the GI tract, uterus, major blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently results in temporary relief of negative symptoms caused by histamine (e.g., stuffy nose, watery eyes).

Pharmacokinetics

Desloratadine is well absorbed from the intestine and reaches peak blood plasma concentrations after approximately three hours. In the bloodstream, 83 to 87% of the substance is bound to plasma proteins. Desloratadine is metabolized to the active metabolite 3-hydroxydesloratadine, which is subsequently glucuronidated and excreted in equal amounts in urine and feces.

Drug Interactions

The potential for drug-drug interactions with desloratadine is considered to be very low. No relevant drug interactions are known to date.

Side effects

The most common side effects are

• tiredness
• Dry mouth
• Headache

Toxicological Data

In animal studies, an oral LD50 was observed at or above doses of 250 mg/kg in rats. This is approximately 120 times a normal therapeutic dose for humans. Therefore, the use of desloratadine is considered to be markedly safe.