[The proarrhythmogenic activity of non-anti-arrhythmia drugs. Is treatment with antihistamines and cisapride safe?].
The non-antiarrhythmic drugs, which possess antiarrhythmic properties could induce dangerous, potentially fatal arrhythmias--extrasystoles, ventricular tachycardia, sudden cardiac arrest. The arrhythmogenic properties are due to block of the potassium channels of the cells and are realized by prolongation of the QT interval on ECG. Accelerating mechanisms are the bradycardia and the hypokalemia. Such drugs are the H1 blockers--astemisol (hismanal) and terfenadine, the prokinetic cisaprid (prepulsid, propulsid, coordinax) and the macrolides. These preparations should be carefully prescribed and not combined with each other, as well as, with antiarrhythmics and blockers of the cytochrome oxidase system (antifungal antibiotics, metronidazole, cyprofloxacin, antidepressants). During their use the patients have to be followed up for changes in QT, bradycardia, arrhythmia, hypokalemia.