Coreg vs. Metoprolol Tartrate

• Carvedilol and metoprolol tartrate are beta-adrenergic blocking agents (beta-blockers) used to treat high blood pressure (hypertension) and congestive heart failure.
• Brand names for carvedilol include Coreg and Coreg CR. Brand names for metoprolol tartrate include Lopressor and Toprol XL.
• Side effects of carvedilol and metoprolol tartrate that are similar include diarrhea, decreased heart rate, and lightheadedness.
• Side effects of carvedilol that are different from metoprolol tartrate include dizziness, edema (fluid accumulation), irregular heart rhythm, vision problems, and postural hypotension (a rapid decrease in blood pressure when going from the seated to the standing position that causes lightheadedness and/or fainting).
• Side effects of metoprolol tartrate that are different from carvedilol include abdominal cramps, constipation, fatigue, insomnia, nausea, depression, memory loss, fever, impotence, low blood pressure, cold extremities, sore throat, and shortness of breath or wheezing.

Carvedilol is used to treat high blood pressure and congestive heart failure. It is related to labetalol (Normodyne, Trandate). Carvedilol blocks receptors of the adrenergic nervous system, which reduces the heart's rate and force of contraction and thereby reduces the work of the heart. Carvedilol also blocks adrenergic receptors on arteries and causes the arteries to relax and the blood pressure to fall. The drop in blood pressure further reduces the work of the heart since it is easier to pump blood against a lower pressure.

Metoprolol is a beta-blocker used to treat high blood pressure, heart pain, abnormal rhythms of the heart, and some neurologic conditions. Other beta-adrenergic blockers include propanolol (Inderal, Inderal LA, Innopran XL), atenolol (Tenormin), and timolol (Blocadren). Metoprolol is also used to treat congestive heart failure and angina pectoris (heart pain) related to coronary artery disease. Other uses for metoprolol include migraine headache prevention, hyperthyroidism, and the treatment of certain types of tremors.

Coreg

The most common side effects of carvedilol are:

• dizziness,
• edema (fluid accumulation),
• decreased heart rate,
• diarrhea and
• postural hypotension (a rapid decrease in blood pressure when going from the seated to the standing position that causes lightheadedness and/or fainting).

Taking carvedilol with food minimizes the risk of postural hypotension.

Other common side effects of carvedilol are irregular heart rhythm, and abnormalities of vision.

Carvedilol should be used cautiously in patients who use diuretics or who are elderly or have cirrhosis, asthma, peripheral vascular disease, hyperthyroidism, Prinzmetal's variant angina (angina at rest), or kidney disease.

Metoprolol Tartrate

Metoprolol is generally well tolerated. Side effects include

• abdominal cramps,
• diarrhea,
• constipation,
• fatigue,
• insomnia,
• nausea,
• depression,
• dreaming,
• memory loss,
• fever,
• impotence,
• lightheadedness,
• low blood pressure,
• cold extremities,
• sore throat, and
• shortness of breath or wheezing.

Possible serious adverse effects include

• slow heart rate,
• Raynaud's phenomenon,
• hepatitis, and
• increased insulin resistance.

Metoprolol can aggravate breathing difficulties in patients with asthma, chronic bronchitis, or emphysema.

WARNING

• In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), metoprolol can cause dangerously slow heart rates, and even shock. Metoprolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure. In patients with coronary artery disease, abruptly stopping metoprolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue metoprolol, its dosage should be reduced gradually over several weeks.
• Initiation of high-dose extended release metoprolol in patients undergoing non-cardiac surgery is associated with bradycardia (slow heart rate), hypotension, stroke, and death. However, long-term therapy with metoprolol should not be routinely withdrawn prior to major surgery. Impaired ability of the heart to respond to reflex adrenergic stimuli may increase the risks of general anesthesia and surgery.

Coreg

• Carvedilol tablets are usually given twice daily. For high blood pressure, the dose is 6.25 mg twice daily to a maximum of 25 mg twice daily.
• For congestive heart failure, the dose is 3.25 mg twice daily to a maximum of 25 mg twice daily. A maximum dose of 50 mg twice daily has been used in persons weighing more than 85 kg (187 pounds).
• Carvedilol should be taken with food to slow its absorption and reduce the occurrence of low blood pressure when rising from a sitting or sleeping position (orthostatic hypotension). Stopping and changing doses of carvedilol should be done under the direction of a physician since sudden changes in dose can result in serious cardiac complications such as arrhythmias.
• The dose range for treating heart failure or high blood pressure with extended release capsules is 10 to 80 mg once daily.

Metoprolol

• Metoprolol should be taken before meals or at bedtime.
• The dose for treating hypertension is 100-450 mg daily in single or divided doses.
• Angina is treated with 100-400 mg daily in two divided doses.
• Heart attack (acute myocardial infarction) is treated with three 5 mg injections administered 2 minutes apart followed by treatment with 50 mg oral metoprolol every 6 hours for 48 hours. After 48 hours, patients should receive 100 mg orally twice daily for at least 3 months.
• The dose for congestive heart failure is 25 mg/daily initially. Then the dose is increased every 2 weeks to reach a target dose of 200 mg/daily orally.
• Hyperthyroidism is treated with 25 to 30 mg by mouth every 6 hours.

Coreg

• Carvedilol can mask early warning symptoms of low blood sugar (hypoglycemia) such as tremors and increased heart rate. (These symptoms are caused by activation of the adrenergic nervous system which is blocked by the carvedilol.) Therefore, patients with diabetes taking medications that lower blood sugar such as insulin or oral anti diabetic medications may need to monitor their blood sugar more often.
• Carvedilol taken with calcium channel blockers (CCBs) such as diltiazem (Cardizem) or verapamil (Calan) may trigger an irregular heart rhythm or an increase in blood pressure.
• Reserpine, monoamine oxidase inhibitors (phenelzine or isocarboxazid) and clonidine (Catapress), because they have similar mechanisms of action as carvedilol, may greatly accentuate the effects of carvedilol and cause a steep decline in blood pressure and/or heart rate. Close monitoring of blood pressure and heart rate may be needed.
• Carvedilol may cause an increase in digoxin (Lanoxin) blood levels. Therefore, in patients receiving digoxin, the digoxin blood level should be monitored if carvedilol is started, adjusted or discontinued.
• Rifampin (Rifadin) can sharply decrease the carvedilol blood level. Therefore, in patients taking rifampin, the dose of carvedilol may need to be increased. Carvedilol shares a common pathway for elimination by the liver with several other drugs such as quinidine (Quinaglute), fluoxetine (Prozac), paroxetine (Paxil), or propafenone (Rythmol).
• Use of these drugs may block the elimination of carvedilol. No studies have been done to confirm these effects on the elimination of carvedilol; however, carvedilol blood levels may be increased (along with the risk for carvedilol's side effects) if patients are taking any of these drugs.
• Carvedilol may increase cyclosporin (Sandimmune, Neoral) blood levels. The dose of cyclosporin may need to be adjusted when the two drugs are used together.
• Amiodarone (Cordarone) may increase carvedilol levels in the blood, increasing the effects and potential for toxicity of carvedilol.

Metoprolol Tartrate

• Calcium channel blockers and digoxin (Lanoxin) can lower blood pressure and heart rate to dangerous levels when administered together with metoprolol.
• Metoprolol can mask the early warning symptoms of low blood sugar (hypoglycemia) and should be used with caution in patients receiving treatment for diabetes.
• Fluoxetine (Prozac) can increase blood levels of metopropol by reducing breakdown of metoprolol, and increase the side effects from metoprolol.

Coreg

Safe use of carvedilol during pregnancy has not been established.

No studies with carvedilol are available in nursing mothers; however, use is not recommended due to the risk of a slow heart rate in the infant.

Metoprolol tartrate

Safe use of metoprolol during pregnancy has not been established.

Small quantities of metoprolol are excreted in breast milk and may potentially cause adverse effects in the infant.