The antihistamines are among the most widely prescribed drugs in the world. For the treatment of allergic diseases. The fi rst generation antihistamines, such as hydroxyzine, dexchlorpheniramine or diphenhydramine, among others, pose the inconvenience of inducing sedative effects and – depending on the molecule involved – anticholinergic, alpha-adrenergic or other actions that limit their usefulness. The introduction of the new second generation, non-sedating antihistamines represented an important advance in the treatment of different allergic disorders, and particularly rhinoconjunctivitis.
These new drugs, which are ever increasing in number (astemizole, terfenadine and fexofenadine, cetirizine and levocetirizine, loratadine and desloratadine, ebastine, mizolastine and rupatadine, as the most salient examples), are relatively free of side effects and offer a broad therapeutic spectrum. However, in the last decade of the twentieth century, reports began to appear of torsades de pointes (TdP) type arrhythmias, arrhythmias, syncope and even sudden death, fundamentally related with astemizole [1] and terfenadine [2], which generated considerable concern and drew attention to the cardiac effects of the antihistamines.. .../... more at PDF full text