LORATADINE - A REAPPRAISAL OF ITS PHARMACOLOGICAL PROPERTIES AND THERAPEUTIC USE IN ALLERGIC DISORDERS

Loratadine is a long-acting antihistamine agent, exhibiting partial se lectivity for peripheral histamine H-1-receptors. To date, loratadine has been evaluated in allergic rhinitis, urticaria and, to a limited e xtent, in asthma. In several large controlled comparative clinical stu dies, loratadine was superior to placebo, faster acting than astemizol e and as effective as azatadine, cetirizine, chlorpheniramine (chlorph enamine), clemastine, hydroxyzine, mequitazine and terfenadine in pati ents with allergic rhinitis and chronic urticaria. The clinical effect iveness of loratadine in asthma is at present unclear Loratadine is we ll tolerated. At dosages of 10mg daily, commonly reported adverse even ts were somnolence, fatigue and headache. Sedation occurred less frequ ently with loratadine than with azatadine, cetirizine, chlorpheniramin e, clemastine and mequitazine. Serious ventricular arrhythmias, as rep orted with some other second generation histamine H-1-receptor antagon ists, have not been observed with loratadine to date. Thus, loratadine , with its attributes of once daily administration, fast onset of acti on and essentially nonsedating properties, would appear to be an appro priate first-line agent for the treatment of allergic rhinitis or urti caria.