Calcium Channel Blocking Agents (Systemic)

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For the calcium channel blocking agents, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to amlodipine, bepridil, diltiazem, felodipine, flunarizine, isradipine, nicardipine, nifedipine, nimodipine, or verapamil. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy - Calcium channel blocking agents have not been studied in pregnant women. However, studies in animals have shown that large doses of calcium channel blocking agents cause birth defects, prolonged pregnancy, poor bone development in the offspring, and stillbirth.

Breast-feeding - Although bepridil, diltiazem, nifedipine, verapamil, and possibly other calcium channel blocking agents, pass into breast milk, they have not been reported to cause problems in nursing babies.

Children - Although there is no specific information comparing use of this medicine in children with use in other age groups, it is not expected to cause different side effects or problems in children than it does in adults.

Older adults - Elderly people may be especially sensitive to the effects of calcium channel blocking agents. This may increase the chance of side effects during treatment. A lower starting dose may be required.

Other medicines - Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When taking calcium channel blocking agents it is especially important that your health care professional know if you are taking any of the following:

• Acetazolamide (e.g., Diamox) or
• Amphotericin B by injection (e.g., Fungizone) or
• Corticosteroids (cortisone-like medicine) or
• Dichlorphenamide (e.g., Daranide) or
• Diuretics (water pills) or
• Methazolamide (e.g., Naptazane) - These medicines can cause hypokalemia (low levels of potassium in the body), which can increase the unwanted effects of bepridil

• Beta-adrenergic blocking agents (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Kerlone], carteolol [e.g., Cartrol], labetalol [e.g., Normodyne], metoprolol [e.g., Lopressor], nadolol [e.g., Corgard], oxprenolol [e.g., Trasicor], penbutolol [e.g., Levatol], pindolol [e.g., Visken], propranolol [e.g., Inderal], sotalol [e.g., Sotacor], timolol [e.g., Blocadren]) - Effects of both may be increased. In addition, unwanted effects may occur if a calcium channel blocking agent or a beta-blocking agent is stopped suddenly after both have been used together

• Carbamazepine (e.g., Tegretol) or
• Cyclosporine (e.g., Sandimmune) or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) - Effects of these medicines may be increased if they are used with some calcium channel blocking agents

• Digitalis glycosides (heart medicine) - Effects of these medicines may be increased if they are used with some calcium channel blocking agents

• Disopyramide (e.g., Norpace) - Effects of some calcium channel blocking agents on the heart may be increased

• Grapefruit juice - Effects of felodipine may be increased. No effects on amlodipine.

Also, tell your health care professional if you are using any of the following medicines in the eye:

• Betaxolol (e.g., Betoptic) or
• Levobunolol (e.g., Betagan) or
• Metipranolol (e.g., OptiPranolol) or
• Timolol (e.g., Timoptic) - Effects on the heart and blood pressure may be increased

Other medical problems - The presence of other medical problems may affect the use of the calcium channel blocking agents. Make sure you tell your doctor if you have any other medical problems, especially:

• Congestive heart failure - Calcium channel blocking agents may make this condition worse
• Heart rhythm problems (history of) - Bepridil can cause serious heart rhythm problems

• Kidney disease or
• Liver disease - Effects of the calcium channel blocking agent may be increased

• Mental depression (history of) - Flunarizine may cause mental depression

• Parkinson's disease or similar problems - Flunarizine can cause parkinsonian-like effects

• Other heart or blood vessel disorders - Calcium channel blocking agents may make some heart conditions worse