Agent nonsedating antihistamine
Mequitazine has an antimuscarinic effect parallel to its H1-antihistamine activity, which can result for example in dryness of mouth or accommodation disturbances.
Loratadine acts mainly via one of its metabolites, decarboethoxyloratadine, also called desloratadine, which is also marketed.
Fexofenadine, the active metabolite of terfenadine is not associated with an averse prolongation of the QT interval.
Ebastine, which is transformed in the body into an active metabolite, carebastine, is a H1-antihistamine in theory not sedative and not antimuscarinic.
Azelastine is a H1-antihistamine usable by local route, in nasal pulverization, in the treatment of allergic rhinitis.
H1-antihistamines are used for supportive care of allergic manifestations, cutaneous (urticaria) or mucous membranes (rhinitis, hayfever, conjunctivitis). Insufficient alone to treat anaphylactic shock or edema of the larynx, they could prevent them.
They have a longer duration of action and longer plasma half-life than the first generationdrugs, which makes it possible to reduce the number of daily intakes.
They were withdrawn from the market because they could induce ventricular arrhrythmias, prolongation of QT interval which can lead to torsades de pointes.
In addition, each compound can have or not have parallel properties, antimuscarinic effects for example.
This distinction between generations must be taken with caution because a product considered as non sedative or not antimuscarinic can, in certain circumstances, large doses or particular susceptibility of the patient ,have these effects.
Oxatomide, is a sedating H1-antihistamine, having mast-cell stabilising properties perhaps by a calcium-channel antagonist effect , without anticholinergic effect.
It is used in treatment of chronic urticaria, atopic dermatitis and dermographisms. Doxylamine is a sedating antihistamine also used as an hypnotic.