Immediate-release tablets: The standard starting dose is 30 mg taken by mouth 4 times per day. Your doctor may slowly increase your dose to 180–360 mg per day taken in 3 to 4 divided doses. Extended-release capsules: The standard starting dose is 120–180 mg taken by mouth once per day. Take this medicine in the dose and duration as advised by your doctor. Swallow it as a whole. Do not chew, crush or break it. Loprin 75 Tablet is to be taken with food. Diltiazem is called a calcium channel blocker. It works by relaxing blood vessels in the body and heart and lowers the heart rate. Blood can flow more easily and your heart works less hard to pump blood. Diltiazem monotherapy was confirmed to be an effective antihypertensive agent. Although mean arterial pressure was reduced from 121 to 108 mm Hg, diltiazem had no overall effect on glomerular filtration rate, renal plasma blood flow, salt and water excretion, or body fluid composition.