Verapamil (brand names: Isoptin, Verelan, Calan, Bosoptin, Covera-HS)'s an L-type calcium channel blocker of the phenylalkylamine class. It's been used in the treatment of hypertension, angina pectoris, cardiac arrhythmia, and most recently, cluster headaches. Verapamil has also been used as a vasodilator during cryopreservation of blood vessels. It's a class 4 antiarrhythmic, more effective than digoxin in controlling ventricular rate, and was approved by the United States Food and Drug Admini… (More on Verapamil)