Source:http://linkedlifedata.com/resource/umls/id/C0717893
NCI: An oral combination preparation containing the antihistamine loratidine and the indirect-acting sympathicomimetic agent pseudoephedrine, with anti-allergic and decongestant activities. Loratadine, a piperidine, blocks the H1-receptor thereby preventing the symptoms that are caused by histamine activity on capillaries, bronchial smooth muscle, and gastrointestinal smooth muscle, including vasodilatation, increased capillary permeability, bronchoconstriction, and spasmodic contraction of gastrointestinal smooth muscle. Pseudoephedrine displaces norepinephrine from storage vesicles in presynaptic neurons, thereby releasing norepinephrine into the neuronal synapses where it stimulates primarily alpha-adrenergic receptors in the nasal mucosa, thereby producing vasoconstriction, reduces swelling of nasal tissues and decreasing nasal and sinus congestion.