Metoprolol

Metoprolol is a prescription medication used to treat high blood pressure, angina (chest pain), congestive heart failure, and to improve survival after a heart attack. Metoprolol belongs to a group of drugs called beta blockers, which work by relaxing blood vessels and slowing heart rate. This improves blood flow and decreases overall blood pressure.

This medication comes in an immediate-release tablet (metoprolol tartrate), an extended-release tablet (metoprolol succinate) and in an injectable form (metoprolol tartrate). 

Common side effects include fatigue, tiredness, and shortness of breath. Metoprolol can cause drowsiness. Do not drive or operate heavy machinery until you know how metoprolol affects you.

CYP2D6 is a protein in your body that is involved in the elimination of metoprolol and other drugs from your body. Some patients have less of this protein in their bodies, affecting how much of the drug gets eliminated. Levels of CYP2D6 can vary greatly between individuals, and those having less of this protein are known as "poor metabolizers." 

CYP2D6 testing is done to determine whether you are a poor metabolizer. If you are a poor metabolizer, the levels of metoprolol in your blood can become too high. As a result you may be at an increased risk of having more side effects from metoprolol. 

Your doctor may adjust your dose of metoprolol if you are a poor metabolizer.

Metoprolol is a prescription medication used alone or in combination with other medications for the following conditions:

• to control high blood pressure
• angina (chest pain)
• in the treatment of congestive heart failure
• to improve survival after a heart attack

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Metoprolol may be found in some form under the following brand names:

• Betaloc

• Dutoprol

• Lopressor

• Lopressor HCT

• Toprol

Serious side effects have been reported with metoprolol. See the “Drug Precautions” section.

Common side effects include:

• fatigue
• dizziness
• depression
• shortness of breath
• a slow heart beat
• low blood pressure
• diarrhea
• itching
• rash

This is not a complete list of metoprolol side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• reserpine (Serpalan, Serpasil)
• monoamine oxidase inhibitors such as tranylcypromine (Parnate), phenelzine (Nardil), selegiline (Eldepryl, Zelapar), isocarboxazid (Marplan), and rasagiline (Azilect)
• medications that block the enzyme CYP2D6 such as paroxetine (Paxil), quinidine (Cardioquin, Duraquin, Quinora), and fluoxetine (Sarafem, Prozac)
• digoxin (Lanoxin)
• clonidine (Catapres)
• calcium channel blockers such as nifedipine (Adalat, Nifedical, Procardia), amlodipine (Norvasc), verapamil (Calan, Isoptin, Covera, Verelan), and diltiazem (Cardizem)

This is not a complete list of metoprolol drug interactions. Ask your doctor or pharmacist for more information.

Serious side effects have been reported with metoprolol including the following:

• heart failure. Worsening cardiac failure may occur. Tell your healthcare provider right away if you experience any of the following symptoms of heart failure:
  • sudden weight gain
  • worsening shortness of breath
  • increased swelling of your feet, legs, or abdomen
  • needing to use more pillows to go to sleep or sleeping in a recliner
  • waking from sleep to catch your breath
  • a cough that does not go away
  • new or increasing irregularities in your heart rate
• diabetes and low blood sugar. Metoprolol may mask symptoms of low blood sugar in those with diabetes. Tell your health care provider right away if you have the following symptoms of hypoglycemia:
  • dizziness
  • sweating
• thyrotoxicosis. Metoprolol may mask symptoms of thyrotoxicosis in those with hyperthyroidism. Avoid abrupt withdrawal of taking metoprolol, which might result in a thyroid storm, a life-threatening situation if left untreated.
• asthma or other bronchospastic conditions. Metoprolol may be used with caution in patients with bronchospastic disease who do not respond to, or cannot tolerate, other similar types of treatment. Tell your health care provider right away if you have the following symptoms of a bronchospasm or asthma attack:
  • wheezing
  • difficulty breathing
  • chest pain
  • coughing
  • chest tightness
• slow heart beat (bradycardia) and/or low blood pressure. Tell your health care provider right away if you have the following symptoms of bradycardia and/or low blood pressure:
  • feeling as if you are going to faint
  • chest pain
  • fatigue
  • shortness of breath
  • dizziness
  • weakness
  • confusion
  • blurry vision

Metoprolol can cause drowsiness. Do not drive or operate heavy machinery until you know how metoprolol affects you.

Metoprolol can cause serious withdrawal side effects. To avoid these side effects, do not suddenly stop taking this medication. Discuss with your doctor about slowly decreasing the dose before stopping use of this medication altogether.

Do not take metoprolol if you:

• are allergic to metoprolol or to any of its ingredients
• have severe bradycardia
• have heart block greater than first degree
• are experiencing angiogenic shock
• have decompensated cardiac failure
• have sick sinus syndrome without a pacemaker
• have peripheral arterial circulatory disorders

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of metoprolol, there are no specific foods that you must exclude from your diet when receiving this medication.

Before taking metoprolol, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• have thyrotoxicosis
• have asthma or other bronchospastic disease
• have about to undergo any type of surgery, including dental surgery
• have liver problems
• have thyroid problems
• have heart problems
• have severe bradycardia
• are experiencing angiogenic shock
• have peripheral arterial circulatory disorders
• are pregnant or breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Metoprolol falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans, though. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child.

Tell your doctor if you are breastfeeding or plan to breastfeed.

Metoprolol has been detected in human breast milk. Because of the possibility for adverse reactions in nursing infants from metoprolol, a choice should be made whether to stop nursing or to stop use of this medication. The importance of the drug to the mother should be considered.

Take metoprolol exactly as prescribed.

Take metoprolol at the same time each day.

This medication comes in tablet and in an injectable form (metoprolol tartrate). The tablet is taken once or twice daily. The injectable form is given directly into a vein (IV) by a healthcare professional.

Metoprolol also comes in an extended-release tablet (metoprolol succinate). The extended-release tablet is taken once a day. Do not chew, divide, or break metoprolol extended release tablets. Swallow tablets whole.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of metoprolol at the same time.

Take metoprolol exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The metoprolol dose your doctor recommends will be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your age

The recommended dose range for metoprolol [tartrate] for treating hypertension is 100 to 450 mg, either taken once a day or twice a day in equally divided doses.

The recommended dose range for metoprolol [tartrate] for treating chest pain is 100 to 400 mg, either taken once a day or twice a day in equally divided doses.

The recommended dose for metoprolol [tartrate] for treating a heart attack is 15 mg at first (by injection), then 25 to 50 mg every 6 hours for the first 48 hours, then 100 mg twice a day in equally divided doses.

The recommended dose range for metoprolol [succinate] for treating hypertension in adults is 25 to 100 mg once a day.

The recommended dose range for metoprolol [succinate] for treating hypertension in children (6 years of age or older) is 0.1 mg/kg to 50 mg once a day.

The recommended dose range for metoprolol [succinate] for treating chest pain is 100 to 400 mg once a day.

The recommended dose range for metoprolol [succinate] for treating heart failure is 12.5 to 200 mg once a day.

If you take too much metoprolol, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

• Store metoprolol tablets at room temperature between 15 and 30°C (59- 86°F).
• Store metoprolol extended release tablets at room temperature between 25°C (77°F).
• Protect from moisture and heat.
• Keep it in the original container.
• Keep this and all medications out of the reach of children.

Following abrupt cessation of therapy with certain beta-blocking agents, exacerbations of angina pectoris and, in some cases, myocardial infarction have occurred. When discontinuing chronically administered metoprolol, particularly in patients with ischemic heart disease, the dosage should be gradually reduced over a period of 1 - 2 weeks and the patient should be carefully monitored. If angina markedly worsens or acute coronary insufficiency develops, metoprolol administration should be reinstated promptly, at least temporarily, and other measures appropriate for the management of unstable angina should be taken. Warn patients against interruption or discontinuation of therapy without the physician’s advice. Because coronary artery disease is common and may be unrecognized, it may be prudent not to discontinue metoprolol therapy abruptly even in patients treated only for hypertension