Drug Therapy: Calcium-Channel Blockers

Calcium-channel blockers cause the blood vessels to relax by slowing the rate at which calcium passes into the heart muscle and blood vessel walls. As the blood vessels relax, more blood can flow through them, lowering the blood pressure. Calcium-channel blockers are prescribed to manage high blood pressure, chest pain (angina) or irregular heartbeats (arrhythmia).

If these medications are prescribed, the doctor should be made aware of any other drug, vitamin, mineral or herbal supplement the patient is taking, especially:

  • Antiarrhythmics
  • Anti-inflammatory drugs, such as corticosteroids
  • Calcium
  • Digitalis
  • Diuretics
  • High blood pressure medicine (particularly beta blockers and ACE inhibitors)
  • Medications for certain eye conditions
  • Vitamin D
The doctor should be told if the patient has:
  • Allergies to foods or dyes
  • Very low blood pressure
  • Heart failure or other heart or blood vessel conditions
  • Arrhythmia
  • Kidney or liver disease
  • Low blood sugar because calcium-channel blockers can make this condition worse
  • Parkinson's disease
  • A history of depression
Patients should avoid smoking, which may cause a rapid heartbeat (tachycardia), and should wait at least four hours after taking a calcium-channel blocker before eating grapefruit or drinking grapefruit juice, which may interfere with the body's ability to absorb calcium-channel blockers.
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