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