Calcium channel blockers are a class of drugs that prevent the entry of calcium into the heart muscles and the smooth muscle cells present in the wall of the blood vessels. The smooth muscle cells of the arteries, as well as the heart muscles require calcium to contract, and calcium enters these cells through some tiny channels.
By preventing the entry of calcium into these cells, calcium channel blockers help relax or dilate the blood vessels, which is termed as vasodilation. This reduces the pressure exerted by the circulating blood on the arterial wall. A low level of calcium in the heart muscles decreases cardiac contractility, or the force with which the myocardium of the heart contracts. This in turn, reduces cardiac output. The cumulative effect of vasodilation and low cardiac contractility is a drop in blood pressure.
As mentioned already, these medications help lower blood pressure. So, they are basically used in the treatment of high blood pressure or hypertension. As they help widen or dilate the arteries, they are also used in conditions like angina, pulmonary hypertension, cardiomyopathy, Raynaud's phenomenon, and subarachnoid hemorrhages.
Calcium channel blockers are especially effective in treating hypertension in African-American people. However, for others, they are not considered more effective than beta blockers and ACE (angiotensin-converting enzyme) inhibitors. Migraines, brain aneurysm complications, and irregular heartbeat are some other conditions, for which these medications can be used. Amlodipine, diltiazem, nicardipine, and verapamil are some commonly used calcium channel blockers. Differences exist among these medications regarding their effects on the heart rate, as well as the duration of their action.
Calcium Channel Blockers Dangers
They are generally used along with beta blockers, in order to lower blood pressure. Like beta blockers, they can produce some mild to severe side effects. However, the incidence of serious side effects are rare. The side effects that are more commonly observed are, headaches, constipation, heartburn, nausea, low blood pressure, tiredness, dizziness, swelling of the legs due to edema or fluid retention, and drowsiness. Some people can experience swollen and bleeding gums, an upset stomach, hot flashes, abdominal pain, gastroesophageal reflux disease, and tingling of the hands and feet.
Shortness of breath and wheezing, yellowing of the skin and the eyes, irregular and slow heartbeat, and an allergic reaction (that can manifest in skin rash and hives) are some serious side effects associated with these hypertension medications. If you observe any of these side effects, be sure to inform your physician as soon as possible. Liver dysfunction can be another major side effect of these drugs. In addition to these, these medications can interact with some food and other medications. In general, calcium channel blockers can interact with grapefruit, alcohol, and certain medications like carbamazepine, simvastatin, lovastatin, etc.
So, before taking these drugs, one should disclose all information regarding the use of other medications, herbs, or supplements to a physician. Expecting and breastfeeding mothers should never take these drugs without consulting a physician. However, so far, no major side effects have been observed in breastfed babies. But still, it is better to maintain precaution, as some studies carried out in animals have found that these medications can have some adverse effects on the unborn fetus. So, these hypertension medications should be taken only under the supervision of a physician.
Disclaimer: This article is for informative purposes only, and should not be treated as a substitute for professional medical advice.