Calcium channel blockers or calcium antagonists are drugs that regulate the influx of calcium into the smooth muscle cells present on the heart and the walls of the arteries. These are available in short-acting and long-acting forms. While the short-acting form provides quick relief, its effects are not long-lasting. The long-acting form may take some time to produce the required results, but it has a long-lasting effect. Calcium channel blockers are also categorized into dihydropyridine and non-dihydropyridine derivatives. While the former doesn't have any effect on the heart rate, the latter slows down the heart rate. Amlodipine besylate is a long-acting dihydropyridine derivative that is sold under the brand name Norvasc. It is mainly used for the treatment of chronic stable angina and hypertension. Being a dihydropyridine derivative, it doesn't slow down the heart rate. How Does it Work The need for calcium channel blockers arises when the release of calcium into the smooth muscle cells that line the coronary arteries causes them to contract. The entry of calcium increases the force of contraction of the cardiac muscle and also leads to constriction of arteries, which in turn, leads to an increase in pressure exerted by blood on the arterial walls. The narrowing of arteries also reduces the flow of oxygenated blood to the heart. This leads to the weakening of the heart muscle. When the supply of oxygenated blood to an area of the heart muscle gets reduced, one experiences chest pain or angina. Since the body's need for oxygen-rich blood increases after exertion, episodes of chest pain occur after indulging in physical activities. Since calcium channel blockers prevent calcium from entering into the arterial walls, it helps in dilation of the coronary arteries. When the arteries dilate, the heart doesn't have to work harder to pump blood. When the smooth muscles of the arterial walls and heart muscle stays relaxed, the risk of severe heart ailments and hypertension is greatly reduced. Thus, when people affected by stable angina take this drug, they can indulge in physical activities without having to worry about chest pain that would otherwise be experienced after exertion. Side Effects Though amlodipine besylate is quite effective in alleviating the symptoms of chronic stable angina and hypertension, one must always have it as per prescribed dosage. While prescribing this drug to a patient, doctors analyze the patient's medical history and consider factors such as age and overall health so as to ascertain the right dosage. An overdose can have serious repercussions on one's health, so, make sure that you adhere to the advice of the doctors regarding the dosage. If you miss a dose, don't double the dose so as to compensate for the missed dose. Sudden withdrawal or change in dosage may also cause certain side effects. Patients must also inform the doctors about any other medicines they may be taking. This is to rule out the chances of an adverse drug interaction. Since metabolism of this drug takes place in the liver, a high dosage can adversely affect those who have been diagnosed with liver problems. There isn't conclusive evidence on the effect of this drug on pregnant women and nursing mothers. This is why this drug is usually not prescribed for pregnant women, nursing mothers and children. Caution must be exercised while prescribing this medication for patients affected by congestive heart failure or severe coronary artery disease. There have been instances, where people affected by severe coronary artery disease have complained of chest pain on starting this drug. On rare occasions, it may cause a heart attack. As is the case with most drugs, certain side effects may be associated with the use of this long-acting calcium channel blocker. Some people may be allergic to the active ingredients of this drug and may suffer from hives, itching, wheezing or difficulty in breathing or swallowing on taking this drug. Water retention, heart palpitations, dizziness, nausea, diarrhea, drowsiness, flushed skin, constipation, loss of appetite, or fatigue may also be felt by patients. If one experiences any of these side effects, one must report them to the doctor at the earliest. This drug doesn't usually lower blood pressure, but if one is taking another drug for lowering blood pressure, blood pressure may drop. Though it helps in the treatment of heart-related conditions such as angina, an overdose can affect the cardiovascular system. If not taken as per the prescribed dosage, this calcium channel blocker may cause a rapid and irregular heartbeat. The side effects of amlodipine besylate are usually associated with an overdose, but adverse drug interactions and certain medical conditions could also make one more susceptible to untoward effects. Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.