<unk>  is a antiarrhythmic Group IA , cardiovascular agent that is FDA approved for the treatment of ventricular arrhythmias such as sustained ventricular tachycardia, that, in the judgment of the physician, are life-threatening. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include negative inotropic effect on myocardium, constipation, nausea, xerostomia, muscle weakness, blurred vision, delay when starting to pass urine, urinary retention, generalized aches and pains, malaise and fatigue.
Disopyramide
Gadoversetamide
Dimenhydrinate
Pirenzepine
Pizotifen
Arbutamine
Pilocarpine 
Thiomersal