Esloray Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of Action: Desloratadine, the active descarboethoxy metabolite of loratadine, is a second generation antihistamine and long-acting tricyclic histamine antagonist with selective H1-receptor histamine antagonist activity. Desloratadine shows significant interaction with the human histamine H1-receptor. Desloratadine inhibited histamine release from human mast cells in vitro.
Pharmacokinetics: Absorption: Onset: Following single- and multiple-dose administration, antihistaminic effects occur within 1 hour.
Symptomatic (nasal and non-nasal) improvement observed as early as 1 day after initiation of therapy.
Duration: Following single- and multiple-dose administration, antihistaminic effects persist for up to 24 hours. No evidence of histamine-induced skin wheal tachyphylaxis over 28-day treatment period.
Food: Food or grapefruit juice does not appear to affect bioavailability following administration as conventional tablets, oral solution, or fixed-combination tablets.
Special Populations: In patients with renal impairment and those who require hemodialysis, peak plasma desloratadine concentrations and AUC are increased.
Distribution: Plasma Protein Binding: Approximately 82-87% (for desloratadine) and 85-89% (for 3-hydroxydesloratadine).
Special Populations: Protein binding not altered in patients with renal impairment.
Metabolism: Extensively metabolized to 3-hydroxydesloratadine (active metabolite), which subsequently undergoes glucuronidation; enzyme(s) responsible for metabolism of desloratadine not identified.
Excretion: Approximately 87% excreted as metabolic products in urine and feces in equal proportions. Desloratadine and 3-hydroxydesloratadine are poorly removed by hemodialysis.
Half-life: 27 hours for desloratadine and 3-hydroxydesloratadine.
Special Populations: In patients ≥65 years of age, plasma desloratadine concentrations are increased and elimination half-life is prolonged. In patients with hepatic impairment, AUC and elimination half-life are increased and clearance is decreased.