Coreg
Meaning of Coreg: A beta blocker that also relaxes blood vessels, used to steady a failing heart rather than simply to slow the pulse.
Definition of Coreg
Coreg is a brand name for carvedilol, a drug that blocks the effect of adrenaline on the heart and on blood vessels. It blunts beta receptors, which slows the heart and reduces the force of each beat, and it also blocks alpha receptors in vessel walls, so the vessels widen. It is used in long-term heart failure and in high blood pressure.
What does it block, and where?
The receptors sit on heart muscle and on the smooth muscle of vessel walls, not on nerve cells. Adrenaline and related messengers normally dock there and drive the heart faster and harder. Carvedilol occupies the same sites so those signals go unheard.
| Receptor | Where it sits | Effect of blocking it |
|---|---|---|
| Beta-1 | Heart muscle | Slower rate, weaker contraction, lower oxygen demand |
| Beta-2 | Airways and some vessels | Airways may narrow, which matters in asthma |
| Alpha-1 | Walls of arteries | Vessels dilate, so pressure falls |
Why is it given in heart failure?
A heart that pumps poorly is driven hard by adrenaline. That rescue works for hours or days and is corrosive over years, because the constant stimulation wears the muscle out and provokes rhythm disturbances. Blocking the drive reverses part of that damage, and in congestive heart failure with reduced pumping strength this class of drug lengthens life. The trade-off is that removing the drive can make symptoms worse at first, which is why treatment starts at a very low dose and is increased in small steps over weeks.
What are the drawbacks?
Tiredness, dizziness on standing and a slow pulse are the common ones, and they are most pronounced early. Because carvedilol is nonselective it also reaches beta receptors in the airways, so wheeze can worsen in people with asthma. It blunts the tremor and racing pulse that usually announce a low blood sugar, which changes how a low is noticed in someone taking insulin. Stopping abruptly after long use can provoke a rebound of chest pain or rhythm problems. In high blood pressure it is effective but is generally not the first drug chosen, since other classes lower pressure with fewer effects on heart rate and energy.
What is the difference between Coreg and Coreg CR?
The plain tablet contains carvedilol and is taken twice a day. The controlled-release capsule contains carvedilol phosphate, a salt chosen so the drug is released slowly enough for once-daily use. The active molecule is the same in both, and the doses are not interchangeable number for number.
Also known as
Used in a sentence
Carvedilol was started at a low dose and increased gradually for heart failure with reduced ejection fraction.
Good to know
Carvedilol is nonselective, so it reaches beta receptors in the airways as well as the heart, and it blunts the tremor and racing pulse that otherwise signal a low blood sugar.