Carvedilol and metoprolol are both beta blockers, but differ mainly in their selectivity of which beta-receptors they block. Carvedilol blocks both alpha and beta receptors and metoprolol is more cardioselective, that is, more selective to the heart. Depending on the manufacturers, the trade names of these medications differ from country to country.
Both carvedilol and metoprolol are used to treat hypertension and cardiac conditions such as angina or congestive cardiac failure. They work by blocking beta receptors around the heart which prevents the action of adrenaline and noradrenaline, the fight or flight hormones. This slows the heart down and, in turn, reduces the pressure both on the heart and blood pressure. Unlike metoprolol, carvedilol also has some blocking action on alpha receptors, which causes widening of the blood vessels and less resistance, thus also lowering blood pressure.
While the mechanisms of action of carvedilol and metoprolol differ slightly in their selectivity, they share possible adverse effects with all beta blockers. Commonly experienced side effects may include slowed heart beat, dizziness, drowsiness and other CNS effects and gastrointestinal side effects. Driving and operating heavy machinery should be avoided at the initiation of therapy, until tolerance is ensured. Any unwanted or severe side effects should be discussed with the prescribing doctor.
As with any medication, both carvedilol and metoprolol may be contraindicated in some people with underlying clinical conditions. These should be discussed with the doctor before initiating treatment. Pregnancy, desired pregnancy and lactation should also be discussed. Patients with asthma should not use beta blockers.
Different pharmaceutical preparations of both carvedilol and metoprolol are available. They are both taken orally, usually once daily although sometimes they may be taken twice daily according to response. In some countries sustained- or controlled-release preparations are available. In most cases dosage will be started low and titrated up according to tolerance and response.
The prescribed dose should never be exceeded. The lowest effective dose will be given to minimize unwanted side effects and, in most cases, treatment will be long-term. Regular check-ups with the prescribing doctor are necessary for follow-up and maintenance.
While the differences between carvedilol and metoprolol are slight and they may be used successfully to treat the same conditions, response may differ from patient to patient. The prescribing doctor will make a decision according to the clinical picture of each patient and treat accordingly. Initially some treatment and/or dosage changes may be necessary before optimal control is obtained.