Calaptin Sr 240 Mg Tablet Online in USA To diagnose supraventricular tachycardia, a rhythm disturbance of the heart. It is also recommended for controlling heart rate response to other rhythm disturbances, specifically atrial fibrillation and atrial flutter. It may also be helpful for other conditions as determined by your health expert. Calatine SR 240 Mg drug is a calcium channel blocker. It functions by slowing the electrical conduction in the heart, slowing heart, rate, and normalizing heart rhythm. Verapamil medicine or tablet is sold under various trade names, some of which are calan and Calaptin etc.