What Are Calcium Channel Blockers?
Calcium makes your heart and blood vessels work harder to pump. Calcium channel blockers work by slowing the movement of calcium into the cells of the heart and blood vessel walls, which makes it easier for the heart to pump and widens blood vessels. Because your heart doesn't have to work as hard, calcium channel blockers lower your blood pressure.
Certain calcium channel blockers slow your heart rate, which in turn lowers your blood pressure. Your doctor may also prescribe these medicines to treat chest pain (angina) or treat an irregular heartbeat (arrhythmia).
You might receive a short-acting calcium channel blocker or a long-acting one, depending on your condition. The short-acting versions take effect quickly but diminish after a few hours. Slower-releasing, longer-acting forms work longer.
Examples of calcium channel blockers include:
- Norvasc (amlodipine)
- Plendil (felodipine)
- DynaCirc (isradipine)
- Cardene (nicardipine)
- Procardia XL, Adalat (nifedipine)
- Cardizem, Dilacor, Tiazac, Diltia XL (diltiazem)
- Sular (Nisoldipine)
- Isoptin, Calan, Verelan, Covera-HS (verapamil)
Calcium channel blockers vs. beta-blockers
Beta-blockers work similarly to the kinds of calcium channel blockers that slow your heart and lower blood pressure. Because beta-blockers expand blood vessels, your blood flow is improved. Beta-blockers are safer to take if you have heart failure. Calcium channel blockers appear to work more effectively than beta-blockers for Black people.
Calcium channel blockers vs. ACE inhibitors
Angiotensin 2 is an enzyme that narrows blood vessels and creates a hormone that raises blood pressure. Angiotensin-converting enzyme inhibitors (ACE inhibitors) are a class of drugs that block the production of these enzymes. ACE inhibitors and calcium channel blockers both work well in lowering blood pressure and reducing related risks of heart disease, heart failure, and stroke. However, studies have found that calcium channel blockers provide better protection against stroke, and ACE inhibitors provide better protection against heart failure.
Types of Calcium Channel Blockers
There are two types of calcium channel blockers.
Nondihydropyridine calcium channel blockers
Because these medicines work on your heart muscle as well as blood vessels, they are also used to treat irregular heart rhythms. Also known as non-DHP calcium channel blockers, the drugs verapamil and diltiazem are the only nondihydropyridine calcium channel blockers.
Dihydropyridine calcium channel blockers
Dihydropyridines (DHP calcium channel blockers) lower blood pressure by relaxing blood vessels.
What's the difference in dihydropyridine vs. nondihydropyridine calcium channel blockers?
The two types of calcium channel blockers differ in which sites in calcium channels they bind to. Dihydropyridines are more likely to bind to blood vessel channels. Nondihydropyridines tend to bind to cardiac channels, which is why they're effective in lowering your heart rate.
How Do Calcium Channel Blockers Work?
Your body uses calcium to carry things in and out of cells. Like canal locks, calcium enters the cells through channels that regulate the type of cell that can enter and exit. Calcium channel blockers target the calcium channels located in specific areas of your body. Different calcium channel blockers target different areas.
Your blood vessels need calcium to contract and send blood through the body. Too much calcium makes your vessels and heart work harder. At the correct dose, calcium channel blockers stop just some of the calcium entering the cell's calcium channels. This helps your arteries relax and send more oxygen-filled blood to your heart. Nondihydropyridine calcium channel blockers work on the heart's electrical cells to help your heart muscle slow and relax, too.
What Conditions Do Calcium Channel Blocker Treat?
Calcium channel blockers are most commonly used to treat high blood pressure (hypertension). However, they are approved to treat a variety of issues including:
Irregular heart rhythms
An enlarged heart
Coronary artery spasm
Pulmonary hypertension (high blood pressure in lung arteries)
Bleeding in the space between your brain and skull
Doctors prescribe calcium channel blockers "off label" to treat other heart and non-heart-related conditions. Off-label means a drug is effective in treating a disease it wasn't specifically made for. Doctors are allowed to do this as long as the treatment is safe and effective.
Calcium channel blockers for Afib (atrial fibrillation). Atrial fibrillation is an abnormal heart rhythm that puts you at higher risk for stroke. A nondihydropyridine calcium channel blocker to control your heart rate is a first-line treatment for this condition.
Calcium channel blockers for angina. Stable angina is periodic chest pain that occurs when your heart isn't receiving enough blood. You may feel this pain when stressed, exercising, or in the cold. Calcium channel blockers are an effective treatment for angina caused by exertion. They are the preferred treatment for angina caused by coronary artery spasm.
Calcium channel blockers for migraine. Because of their ability to relax blood vessels, doctors have found calcium channel blockers to be an effective treatment against migraine including migraine with aura and complicated migraine as well as cluster headaches.
Calcium channel blockers for heart failure. Heart failure is a reduction in your heart's ability to pump blood. Calcium channel blockers are typically not recommended to treat heart failure, especially if it impacts the lower left chamber of your heart (left ventricle).
Calcium Channel Blocker Side Effects
Depending on the type of calcium channel blocker you take, you may have the following side effects:
- Dizziness or lightheadedness
- Swelling in your ankles, feet, or lower legs (edema)
- Heart rhythm problems (palpitations)
Some types of calcium channel blockers may lead to gingival hyperplasia, excess growth of your gum tissue.
Guidelines for Calcium Channel Blockers
Before taking a calcium channel blocker, tell your doctor:
What if I miss a dose?
If you forget or can't take your medicine, don't "double up" on a dose. Calcium channel blockers are carefully dosed to be safe and work effectively. If you miss a dose, just wait until your next one. Because a nondihydropyridine calcium channel blocker like verapamil affects your heartbeat, taking too much could be life-threatening.
Stopping calcium channel blockers
The side effects of calcium channel blockers can be annoying but are not usually serious. Even so, if you find the side effects to be troubling, tell your doctor. Other medications can be used to successfully treat high blood pressure. Don't suddenly stop taking your calcium channel blockers. Doing so may raise your blood pressure or cause chest pain.
Who should avoid calcium channel blockers?
Those with certain types of heart conditions, liver disorders, or low blood pressure should not take calcium channel blockers. Likewise, if you are pregnant, trying to become pregnant, or breastfeeding, you should not take them.
How Should I Take Calcium Channel Blockers?
Most calcium channel blockers can be taken with food or milk; however, ask your doctor. Follow the label directions on how often to take it. The number of doses you take each day, the time allowed between doses, and how long you need to take the medicine will depend on the type of medication prescribed and on your condition. Avoid grapefruit juice while taking these medications, because grapefruit prevents the breakdown of the drug in the body.
Be sure to see your doctor on a regular basis to make sure the medicine is working as it should and isn't causing any intolerable side effects. Your doctor may want to change the dosage if the drug isn't having the intended effect.
Interactions with Calcium Channel Blockers
- Grapefruits and grapefruit juice can affect the action of many of the calcium channel blockers. Ask your doctor or pharmacist whether your calcium channel blocker is affected by grapefruit juice.
- Do not drink alcohol while taking a calcium channel blocker. Alcohol interferes with the effects of the drug and increases the side effects.
- Taking other blood pressure medications in combination with a calcium channel blocker may cause a sudden drop in blood pressure. Discuss with your doctor the best way to take the medication if you are taking other drugs.
Can I Stop Taking Calcium Channel Blockers?
For certain heart conditions, you may need to take calcium channel blockers for life. But if you're able to greatly change a hypertension risk factor and lower your blood pressure, you may be able to stop taking your calcium channel blocker. If it's right for you, your doctor can help wean you off the calcium channel blockers safely.
If you're able to change one or more of these risk factors by, say, losing weight or reducing your alcohol intake and you start to feel dizzy or lightheaded, check your blood pressure. Your blood pressure may be too low and you may need to adjust your dosage or stop taking calcium channel blockers altogether. But, again, do this with your doctor's guidance.
When Should I See My Doctor?
Pay attention to any new symptoms and call your doctor right away if you notice:
- Trouble breathing
- A sudden onset of chest pain or chest pain that is noticeably different or more frequent
- Skipped heartbeats, racing, or pounding in your chest
- Frequent dizziness, lightheadedness, or fainting
- An unusual rash or irritated skin
- Swelling of your hands and feet or lips, tongue, and eyes
Calcium channel blockers are generally safe and effective medicines for treating high blood pressure and certain heart conditions. Calcium channel blockers can be used with other medications to treat high blood pressure or angina if they haven't worked well on their own. Your doctor will probably start you on a low dose of whatever calcium channel blocker they prescribe and adjust your dosage until your blood pressure falls to within a normal range.
Calcium Channel Blockers FAQs
What is the most commonly prescribed calcium channel blocker?
Amlodipine (brand name Norvasc), a dihydropyridine, is the calcium channel blocker prescribed most frequently. It is a longer-acting calcium channel blocker.
What is considered a calcium channel blocker?
In addition to Norvasc, other brand names for calcium channel blockers include Cardizem, Procardia, Tiazac, and Verelan.
Are calcium channel blockers vasodilators?
Yes. Dihydropyridine calcium channel blockers are considered vasodilators because they work to relax blood vessels, which is why they are used in treating coronary artery spasm and migraine as well.
Who should avoid calcium channel blockers?
You should not take nondihydropyridine calcium channel blockers (diltiazem, verapamil) if you have or are at risk for left ventricle heart failure. The same is true for those with liver conditions, low blood pressure, and those who are pregnant, trying to get pregnant, or breastfeeding.
What are the 2 types of calcium channel blockers?
Nondihydropyridine calcium channel blockers work by relaxing blood vessels (except nimodipine, which is used to treat a certain type of brain bleed called subarachnoid hemorrhage). Nondihydropyridine calcium channel blockers also relax blood vessels but treat arrhythmias (irregular heartbeats) as well.