• Antianginal
• antihypertensive

Mibefradil (mi-be-FRA-dil) belongs to a group of medicines called calcium channel blocking agents, or, more commonly, calcium channel blockers.

Calcium channel blocking agents affect the movement of calcium into the cells of the heart and blood vessels. As a result, they relax blood vessels and increase the supply of blood and oxygen to the heart while reducing its workload.

Mibefradil is used to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Mibefradil is also used to treat recurring chest pain (angina pectoris). Angina occurs when the vessels that carry blood to the heart become narrowed and blocked, reducing the supply of blood and oxygen to the heart. As a result, chest tightness and/or a pressing or squeezing pain can occur. Mibefradil is thought to reduce angina by increasing the supply of blood and oxygen to the heart.

Mibefradil may also be used for other conditions as determined by your doctor.

The medicine was withdrawn from the U.S. market in May 1998.

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 mibefradil, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to mibefradil. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Mibefradil has not been studied in pregnant women. However, studies in animals have shown that large doses of mibefradil can cause heart defects in rat fetuses. Before taking this medicine, make sure your doctor knows if you are pregnant or may become pregnant.

Breast-feeding—It is not known if mibefradil passes into breast milk, however, it passes into the milk of lactating rats. Newborn babies have been reported to be sensitive to other calcium channel blocking agents. Be sure you have discussed the risks and benefits of this medicine with your doctor.

Children—Although there is no specific information comparing use of mibefradil 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 more sensitive to the heart rate slowing effects of mibefradil.

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 you are taking mibefradil, it is especially important that your health care professional know if you are taking any of the following:

• Astemizole (e.g., Hismanal) or
• Cisapride (e.g., Propulsid) or
• Terfenadine (e.g., Seldane)—These medicines should not be used with mibefradil because unwanted effects of these medicines on the heart may be increased

• Atorvastatin (e.g., Lipitor) or
• Cerivastatin (e.g., Baycol) or
• Lovastatin (e.g., Mevacor) or
• Simvastatin (e.g., Zocor)—These medicines should not be used with mibefradil because unwanted effects of these medicines, such as muscle aches or cramps (rhabdomyolysis), may be increased and may lead to development of kidney problems

• Beta-adrenergic blocking agents (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Kerlone], carteolol [e.g., Cartrol], carvedilol, [e.g., Coreg], 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]) or
• Digitalis glycosides (e.g., Lanoxin) or
• Diltiazem (e.g., Cardizem) or
• Verapamil (e.g., Calan)—Effects to slow the heart rate may be increased

• Cyclosporine (e.g., Sandimmune) or
• Desipramine (e.g., Norpramin) or
• Imipramine (e.g., Tofranil) or
• Tacrolimus (e.g., Prograf)—Effects of these medicines may be increased if they are used with mibefradil

• Flecainide (e.g., Tambocor) or
• Propafenone (e.g., Rythmol)—Unwanted effects of these medicines on the heart may be increased

• Heart rhythm or heart rate problems—Mibefradil can worsen these conditions

Take this medicine exactly as directed. This medicine works best if you take it at the same time each day; however, do not take more of this medicine and do not take it more often than your doctor ordered. Do not miss any doses.

Swallow the tablet whole, without crushing or chewing it.

For patients taking this medicine for high blood pressure :

• In addition to the use of the medicine your doctor has prescribed, appropriate treatment for your high blood pressure may include weight control and care in the types of food you eat, especially foods high in sodium (salt). Your doctor will tell you which factors are most important for you. You should check with your doctor before changing your diet.
• Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
• Remember that this medicine will not cure your high blood pressure but it does help control it. Therefore, you must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life . If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.

Dosing—

The dose of mibefradil will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of mibefradil. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking mibefradil.

• For oral dosage form (tablets):
  • For angina (chest pain):
    • Adults—50 milligrams (mg) once a day to start. Your doctor may increase your dose.
    • Children—Use and dose must be determined by your doctor.
  • For high blood pressure:
    • Adults—50 mg once a day to start. Your doctor may increase your dose.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is important that your doctor check your progress at regular visits. This will allow your doctor to make sure the medicine is working properly and to change the dosage if needed.

If you have been using this medicine regularly for several weeks, do not suddenly stop using it. Stopping suddenly may bring on your previous problem. Check with your doctor for the best way to reduce gradually the amount you are taking before stopping completely.

For patients taking this medicine for chest pain:

• Chest pain resulting from exercise or physical exertion is usually reduced or prevented by this medicine. This may tempt you to be overly active. Make sure you discuss with your doctor a safe amount of exercise for your medical problem.

For patients taking this medicine for high blood pressure:

• Do not take other medicines unless you have discussed them with your doctor.

This medicine may cause some people to become dizzy, drowsy, lightheaded, or to faint. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. If unusual tiredness or fainting occurs, check with your doctor.

This medicine may cause problems in an unborn or newborn child. Check with your doctor if you become pregnant, are planning to become pregnant, or are breast-feeding.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common
  • Dizziness, lightheadedness or fainting, recurring (sudden);  slow heart rate;  swelling of the legs ;  unusual tiredness 
  
  

• Rare
  • Chest pain 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Abdominal pain;  belching, heartburn, or stomach discomfort;  flushing;  headache;  nausea or vomiting;  pounding heartbeat;  stomach pain;  stuffy nose 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.