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Carvedilol is used for treating high blood pressure and congestive heart failure. It is related to labetalol (Normodyne, Trandate). Carvedilol blocks receptors of the adrenergic nervous system, the system of nerves in which epinephrine (adrenalin) is active. Nerves from the adrenergic system enter the heart and release an adrenergic chemical (norepinephrine) that attaches to receptors on the heart's muscle and stimulates the muscle to beat more rapidly and forcefully. By blocking the receptors, carvedilol 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. The FDA first approved carvedilol in 1995.

Carvedilol usually is given twice daily. For high blood pressure, the dose may range from 6.25mg twice daily to a maximum of 25mg twice daily. For congestive heart failure, the dose may range from 3.25mg twice daily to a maximum of 25mg twice daily in persons weighing less than 85kg (187 pounds) or 50mg twice daily in persons weighing more than 85kg (187 pounds). Carvedilol should be taken with food since this increases the amount of absorbed drug that reaches the heart and arteries. 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 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 light-headedness 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), and kidney disease.

Carvedilol can mask early warning symptoms of hypoglycemia (low blood sugar) 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, diabetics taking medications that lower blood sugar such as insulin or oral anti-diabetic medications may need to increase the frequency with which they monitor their blood sugar.

Carvedilol taken with calcium channel blockers 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 (Catapres), 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 the levels in the blood of cyclosporin (Sandimmune, Neoral), and the dose cyclosporin may need to be adjusted when the two drugs are used together.

Carvedilol is used by itself or with a diuretic ("water-pill") to control high blood pressure. Carvedilol also may be used in combination with other drugs to manage mild or moderate congestive heart failure. When combined with other treatments for heart disease among patients with recent heart attacks, carvedilol can reduce the risk of a second heart attack by 40% and increase survival among patients with congestive heart failure.

Tablets should be stored at room temperature, 15- 30°C (59-86°F).