Different studies have reported on antihistamine use in children, with various studies finding evidence that certain antihistamines could be used by children 2 years of age, and other drugs being safer for younger or older children.
-receptors and lacks the central nervous system depressant effects often associated with some of the older antihistamines.
However, high doses can still induce drowsiness through acting on the central nervous system.
Histamine produces increased vascular permeability, causing fluid to escape from capillaries into tissues, which leads to the classic symptoms of an allergic reaction — a runny nose and watery eyes. Antihistamines suppress the histamine-induced wheal response (swelling) and flare response (vasodilation) by blocking the binding of histamine to its receptors or reducing histamine receptor activity on nerves, vascular smooth muscle, glandular cells, endothelium, and mast cells.
Itching, sneezing, and inflammatory responses are suppressed by antihistamines that act on H1-receptors.
The chief metabolite of loratadine, descarboethoxy-loratadine (DCL), is pharmacologically active.
Similar to the parent compound, the pharmacokinetics of DCL are not significantly altered by multiple dosing.