First non sedating antihistamine
Ceterizine is a racemic; one of its isomers called levocetirizine is also released on the market.
Mizolastine does not induce, in usual dosage, prolongation of QT interval; however its combination with macrolides and imidazol antifungal agents is disadvised because of a possible inhibition of its catabolism.
New H1-antihistamines induce only exceptionally drowsiness. This possibility, even rare, must however be taken into account, particularly at time of a first prescription.
Ebastine, which is transformed in the body into an active metabolite, carebastine, is a H1-antihistamine in theory not sedative and not antimuscarinic.Antihistamines are inhibitors of histamine receptors. H1-antihistamines, inhibit competitively H1 receptors and the corresponding effects i. They do not inhibit antigen/antibodies reactions, nor histamine release, they inhibit H1 effects. H1-antihistamines have been used for more than fifty years in treating various allergic manifestations. H1-antihistamines which penetrate into brain elicit, by inhibiting stimulant effect of histamine, drowsiness.The drug to use in severe situations is adrenaline The early H1-antihistamines usually induce drowsiness and their prescription to patients with an activity requiring a normal vigilance, like control of a vehicle, is contra-indicated.By their alpha-adrenolytic effect especially when they are given by parenteral route, they could reduce the vasoconstrictive effect of adrenaline, administered for example in case of anaphylactic shock.
Azelastine is a H1-antihistamine usable by local route, in nasal pulverization, in the treatment of allergic rhinitis.