About loratadinesecond generation h1 antagonist, antihistamine.mechanism of action of loratadineloratadine blocks one type of receptor for histamine (the h1 receptor) and thus prevents activation (activation releasing other chemicals which produce the symptoms associated with allergy) of cells by histamine. drug also has mast cell stabilizing property.interactions for loratadinemacrolide antibiotics, ketoconazole, cimetidine, ranitidine and theophylline: caution should be exerted while co-administration of these drugs which are known to inhibit hepatic metabolism.about pseudoephedrinealpha/beta adrenergic agonist, a phenethylamine derivative, a nasal decongestant.mechanism of action of pseudoephedrineit is a nasal decongestant with alpha-2 agonistic action. it produces local vasoconstriction, reduces blood flow, and causes shrinkage of mucosa which provides relief of nasal congestion. it reduces oedema of the nasal mucosa, thus improving ventilation, drainage and nasa