Desloratadine 5 mg · Tablets

Desloratadine is a long-acting tricyclic histamine antagonist with selective H1-receptor histamine antagonist activity. Receptor binding data indicates that at a concentration of 2 to 3 ng/mL (7 nanomolar), desloratadine shows significant interaction with the human histamine H1-receptor. Desloratadine inhibited histamine release from human mast cells in vitro. Results of a radiolabeled tissue distribution study in rats and a radioligand H1-receptor binding study in guinea pigs showed that desloratadine did not readily cross the blood brain barrier. The clinical significance of this finding is unknown.

Absorption — Following oral administration of a desloratadine 5 mg tablet once daily for 10 days to normal healthy volunteers, the mean time to maximum plasma concentrations (Tmax) occurred at approximately 3 hours post dose and mean steady state peak plasma concentrations (Cmax) and AUC of 4 ng/mL and 56.9 ng∙hr/mL were observed, respectively. Neither food nor grapefruit juice had an effect on the bioavailability (Cmax and AUC) of desloratadine.

The pharmacokinetic profile of desloratadine oral solution was evaluated in a three-way crossover study in 30 adult volunteers. A single dose of 10 mL of desloratadine oral solution containing 5 mg of desloratadine was bioequivalent to a single dose of 5 mg desloratadine tablet. Food had no effect on the bioavailability (AUC and Cmax) of desloratadine oral solution.

Distribution — Desloratadine and 3-hydroxydesloratadine are approximately 82% to 87% and 85% to 89% bound to plasma proteins, respectively. Protein binding of desloratadine and 3-hydroxydesloratadine was unaltered in subjects with impaired renal function.