Lopressor, a type of medication known as a Beta-Blocker, is used in the treatment of high blood pressure, angina pectoris (chest pain, usually caused by lack of oxygen to the heart due to clogged arteries), and heart attack.

When prescribed for high blood pressure, it is effective when used alone or in combination with other high blood pressure medications. Beta-blockers decrease the force and rate of heart contractions, thereby reducing the demand for oxygen and lowering blood pressure. Occasionally doctors prescribe Lopressor for the treatment of aggressive behavior, prevention of migraine headache, and relief of temporary anxiety. Lopressor/Metoprolol also is used to treat abnormal heart rhythms. An extended-release form of this drug, called Toprol-XL, is prescribed for high blood pressure, angina, and heart failure.

Lopressor/Metoprolol is a beta-adrenergic blocking agent. Lopressor (Metoprolol) blocks the action of the sympathetic nervous system, a portion of the involuntary nervous system. The sympathetic nervous system stimulates the pace of the heart beat. By blocking the action of these nerves, metoprolol reduces the heart rate and is useful in treating abnormally rapid heart rhythms. Lopressor (Metoprolol) also reduces the force of heart muscle contraction and lowers blood pressure.

By reducing the heart rate and the force of muscle contraction, Lopressor, metoprolol reduces heart muscle oxygen demand. Since angina occurs when oxygen demand of the heart exceeds supply, metoprolol is helpful in treating angina. Lopressor therefore relaxes blood vessels and helps the heart beat more regularly. It also helps relax the tone of the heart to allow it to function more efficiently.

If Lopressor is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Lopressor with certain high blood pressure drugs such as reserpine (Ser-Ap-Es).

Other medications that might interact with Lopressor include: Albuterol (Proventil, Ventolin), Amiodarone (Cordarone), Barbiturates such as phenobarbital, Calcium channel blockers such as Calan and Cardizem, Cimetidine (Tagamet), Ciprofloxacin (Cipro), Clonidine (Catapres), Epinephrine (EpiPen), Fluoxetine (Prozac), Hydralazine (Apresoline), Insulin, Nonsteroidal anti-inflammatory drugs such as Motrin and Indocin, Oral diabetes drugs such as Glucotrol and Micronase, Paroxetine (Paxil), Prazosin (Minipress), Propafenone (Rythmol), Quinidine (Quinaglute), Ranitidine (Zantac), Rifampin (Rifadin).

Special information on Lopressor, if you are pregnant or breastfeeding: The effects of Lopressor during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, inform your doctor immediately. Lopressor appears in breast milk and could affect a nursing infant. If this medication is essential to your health, your doctor may advise you to discontinue breastfeeding until your treatment with this medication is finished.

Most important fact about Lopressor: If you have high blood pressure, you must take Lopressor regularly for it to be effective. Since blood pressure declines gradually, it may be several weeks before you get the full benefit of Lopressor; and you must continue taking it even if you are feeling well. Lopressor does not cure high blood pressure; it merely keeps it under control.

Side effects of Lopressor cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Lopressor.

More common side effects of Lopressor: May include depression, diarrhea, dizziness, itching, rash, shortness of breath, slow heartbeat, tiredness.

Less common or rare side effects of Lopressor: May include, blurred vision, cold hands and feet, confusion, congestive heart failure, constipation, difficult or labored breathing, dry eyes, dry mouth, gas, hair loss, headache, heart attack, heartburn, low blood pressure, muscle pain, nausea, nightmares, rapid heartbeat, ringing in the ears, short-term memory loss, stomach pain, swelling due to fluid retention, trouble sleeping, wheezing, worsening of heart irregularities.

WHY SHOULD THIS DRUG NOT BE PRESCRIBED?
If you have a slow heartbeat, certain heart irregularities, low blood pressure, inadequate output from the heart, or heart failure, you should not take Lopressor.

SPECIAL WARNINGS ABOUT LOPRESSOR:
If you have a history of congestive heart failure, Lopressor should be used with caution. If you are taking the extended release form of this drug, Toprol-XL, to relieve heart failure, the condition may temporarily be worsened as your dosage is increased. Be sure to alert your doctor to any signs of worsening heart failure such as weight gain or increasing shortness of breath. Do not stop Lopressor abruptly. This can cause increased chest pain and heart attack. Lopressor dosage should be gradually reduced. If you suffer from asthma, seasonal allergies or other bronchial conditions, or liver disease, this medication should be used with caution.
Ask your doctor if you should check your pulse while taking Lopressor. This medication can cause your heartbeat to become too slow. Lopressor may mask some symptoms of low blood sugar in diabetics or alter blood sugar levels. If you are diabetic, discuss this with your doctor. Lopressor may cause you to become drowsy or less alert; therefore, driving or operating dangerous machinery or participating in any hazardous activity that requires full mental alertness is not recommended until you know how you respond to this medication. Notify your doctor or dentist that you are taking Lopressor if you have a medical emergency, or before you have surgery or dental treatment. Notify your doctor if you have any difficulty in breathing.