Mechanism of action of sedating antihistamines
receptor sites, responsible for immediate hypersensitivity reactions such as sneezing and itching.
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. Dosing: Oral: Children: 6-11 months: 1 mg once daily 12 months to 5 years: 1.25 mg once daily 6-11 years: 2.5 mg once daily Children /= 12 years and Adults: 5 mg once daily Supplied Syrup (Clarinex®): 0.5 mg/m L (480 m L) [bubble gum flavor] Tablet (Clarinex®): 5 mg Tablet, orally-disintegrating (Clarinex® Redi Tabs®): 5 mg [contains phenylalanine 1.75 mg/tablet] Adult (usual) Chronic idiopathic urticaria: 60 mg orally twice daily.Clinically, it appears that this delivery of high local concentrations allows for other pharmacologic activity to be expressed.These anti-inflammatory actions may be part of the reason why these drugs also are effective in relieving many symptoms of nonallergic rhinitis, where histamine has much less of a role and where oral antihistamines have traditionally been of minimal help.The alkylamines include brompheniramine (Dimetapp) and chlorpheniramine (Chlor-Trimeton.) These agents cause relatively little sedation, and are used primarily for treatment of allergic reactions.Promethazine (Phenergan), in contrast, is a phenothiazine, chemically related to the major tranquilizers, and while it is used for treatment of allergies, may also be used as a sedative, the relieve anxiety prior to surgery, as an anti-nauseant, and for control of motion sickness.