Physicians prescribe calcium channel blockers to treat hypertension and disorders that affect the blood supply to the heart. They also help prevent angina and are effective in the treatment of irregular heartbeats. There are few risks associated with prolonged use of calcium channel blockers, which can be used safely by people who have asthma.
Function
The movement of calcium into the muscle fibers within the blood vessel walls causes the fibers to contract, narrowing the blood vessels. Calcium channel blockers prevent the movement of calcium across the membranes that line the cells so the muscles are unable to contract and the blood vessels widen. These drugs also slow the passage of electrical impulses through the heart muscle, which helps correct certain types of arrhythmias.
Considerations
While these drugs dramatically improve certain conditions such as severe arrhythmias, angina, hypertension and in some instances migraine headaches, they cannot cure the underlying problem. Therefore, calcium channel blockers need to be taken indefinitely to be effective. In arterial disease, the beneficial effects may continue after use of the drug has stopped; however, the length of time can vary considerably.
Availability
These medications are available in tablet and capsule form in two or three strengths. A standard tablet is taken three to four times a day, while an extended release tablet or an extended release capsule is taken one or two times a day. Tablets should be taken whole, not crushed. However, the verapamil capsule can be opened and sprinkled on food if the individual has trouble swallowing it whole.
Types
Commonly prescribed calcium channel blockers include diltiazem, nicardipine, nifedipine and verapamil. These drugs are maintenance medications, used to control chest pain, but none of them will stop chest pain after it has started. A person should not drink or eat grapefruit three days prior or during taking nifedipine. Most physicians and pharmacists recommend reading the drug information insert, which provides additional information including possible side effects from these medications.
Warnings
A doctor will prescribe these drugs with caution if a person has unstable blood pressure, impaired kidney or liver function, or if a woman is pregnant or breast-feeding. A single extra dose is unlikely to cause problems, but several extra doses may cause dizziness and fainting. Side effects associated with taking calcium channel blockers include constipation, heartburn, dizziness and headache. Serious side effects requiring immediate medical intervention may include swelling, blurred vision, fainting, difficulty breathing, rash, nausea, unusual bleeding or bruising, flu-like symptoms, fever and loss of appetite.
References
- Consumer Reports Health.org: The Calcium Channel Blockers: Comparing Effectiveness, Safety and Price
- U.S. National Library of Medicine, MedlinePlus: Diltiazem
- U.S. National Library of Medicine, MedlinePlus: Nicardipine
- U.S. National Library of Medicine, MedlinePlus: Nifedipine
- U.S. National Library of Medicine, MedlinePlus: Verapamil
