Examples of Calcium Channel Blockers (Calcium Antagonists)
Diltiazem (Cardizem, Dilacor, Tiazac, Diltiazem HCl Extended Release)
Isradipine (DynaCirc, Prescal)
Nifedipine (Adalat, Procardia)
Nisoldipine (Baymycard, Sular, Syscor)
Verapamil (Calan, Isoptin, Verelan, Covera)
What Do They Do in the Body? The movement of calcium in and out of some cells of the heart and arteries plays an important role in their contraction. Calcium channel blockers block the movement of calcium, lowering blood pressure by suppressing the contraction of artery muscles, dilating the arteries, and reducing arterial resistance to blood flow.
What Are They Prescribed For? Calcium channel blockers are prescribed for a variety of heart problems, including angina, arrhythmias (irregular heartbeat), rapid heartbeat, high blood pressure, and CHF. They are also prescribed for migraine headaches and Raynaud’s disease. Those prescribed for high blood pressure include amlodipine, verapamil SR, diltiazem, nicardipine, nifedipine, isradipine, felodipine, and nisoldipine.
What Are the Possible Side Effects? Calcium channel blockers are among the most widely prescribed drugs in North America, and yet they are also among the most dangerous drugs you can take. Although they can be useful in normalizing an irregular heartbeat and spasms in the heart muscle, their long-term use for lowering blood pressure is very questionable.
There are at least two major studies showing that people who use calcium channel blockers to control high blood pressure have a higher risk of dying from heart disease and a higher overall risk of dying than people who use other antihypertensives.
In test rats they caused cancer, and the fast-acting forms of nifedipine have been shown in studies conducted by the National Heart, Lung and Blood Institute to increase the risk of a fatal heart attack.
Some of the more common “adverse reactions” include dizziness; swollen hands and feet (edema); chronic headaches; nausea; giddiness; nervousness; numbness and tingling; diarrhea; constipation; digestive problems such as stomach cramps, gas, and heartburn; dry mouth; gum disease; flushing; urinary tract problems; sexual problems; shortness of breath; muscle cramps and pains; and a cough.
The different types of calcium channel blockers can vary in their actions and side effects quite a bit, so if you must take one, be sure your physician is experienced in prescribing them and be sure to read the drug insert carefully for yourself. We’re not aware of any evidence that using calcium channel blockers long-term will reduce the risk of heart attack or death.
Think Twice About Taking These Drugs If . . .
You have kidney or liver disease. Calcium channel blockers are contraindicated with some types of heart disease, such as sick sinus syndrome. This differs with the type of calcium channel blocker. Talk to your physician, and read your drug information sheet. Dangerous side effects tend to occur more often in patients who are also on beta-blockers. This is a potentially dangerous combination.
What Are the Interactions with Food? Some calcium channel blockers are unaffected by food, some are decreased, and some are increased. Ask your pharmacist, and read your drug information insert. Taking felodipine and nifedipine with grapefruit juice can double drug levels, a potentially deadly interaction, and grapefruit juice can also affect the levels of other types of calcium channel blockers. In general, it’s best not to take medicine with grapefruit juice unless your physician asks you to. Some calcium channel blockers may increase the amount of alcohol that gets into the blood when you have a drink or take medicine containing alcohol.
What Nutrients Do They Throw out of Balance or Interact With? Excess vitamin D may reduce the effectiveness of verapamil. Some calcium channel blockers, including nifedipine and vera-pamil, may bind with minerals in food or supplements, reducing the availability of the drug.
Other Tips on These Drugs. Calcium channel blockers can affect the results of blood and urine tests.
If you’re taking a calcium channel blocker in the dihydropyridine class (i.e., felodipine [Plendil], nifedipine), watch out for dangerous interactions with erythromycin, an antibiotic, which can double felodipine levels. High felodipine levels can cause heart palpitations and low blood pressure.
Prescription Alternatives: Hundreds of Free, Natural, Prescription-Free Remedies to Restore & Maintain Your Health, by Earl L. Mindell, R.Ph, Ph. D, & Virginia Hopkins, M.A. Published by McGraw-Hill.