Carvedilol

What is carvedilol?

Carvedilol is a heart medication that may be prescribed off label in dogs, cats, guinea pigs, and turkeys for the treatment of heart conditions including abnormal heart beat frequencies (arrhythmias) and heart failure due to dilated cardiomyopathy (DCM). Carvedilol is classified as an alpha blocker and beta blocker. There are no veterinary brands of carvedilol, but several generic human brands.

Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label. 

How do I give my pet carvedilol?

• Carvedilol is given by mouth in a tablet format. Tablets come in varying strengths. 
• Carvedilol extended-release capsules are available but information about their use in veterinary medicine is not documented.
• Follow the instructions of the label of your product, in conjunction with your veterinarian’s directions. 
• This medication may also be compounded into a liquid oral suspension.
• It is recommended to give carvedilol with food.
• Ideally, give this medication at the same time daily.
• When starting this medicine for your animal, your veterinarian may begin with a low dose and gradually increase the dose over time. It is critical to be aware of the changing doses and not administer more at one time than your veterinarian prescribes. 
• Do not stop the medication without talking with your veterinarian first.

This medication should start having effects within 1 to 2 hours; however, you will not see the effects outwardly. Your veterinarian will need to run further tests to determine if the medication is working appropriately.

What if I miss giving my pet the medication?

If you miss a dose of carvedilol, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once. 

Are there any potential side effects?

Carvedilol may cause the following side effects:

• Lack of energy or acting tired, usually at the beginning of treatment

Serious adverse reactions associated with this drug may occur without warning and could, in rare cases, lead to death. If any of the following signs develop, stop giving carvedilol and contact your veterinarian immediately:

• loss of appetite
• very slow heart rate
• collapse or fainting
• coughing, wheezing, or trouble breathing

These signs are rare but may indicate the starting dose of carvedilol is too high.

Drug sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

This short-acting medication should stop working within 24 hours, although effects may be longer in pets with liver or kidney disease. 

It is not recommended to stop this medication abruptly. 

Are there any risk factors for this medication?

This medication should NOT BE USED in pets who:

• are allergic to it or other drugs like it 
• have severe heart failure, asthma, heart block, or very slow heart rates.
• are in shock

This medication should be USED WITH CAUTION in pets who: 

• have liver problems.
• have active heart failure or a history of heart failure

Are there any drug interactions I should be aware of?

Certain medications may interact with carvedilol and so it is important to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your dog is taking before starting any new treatment.

Several medications should be used with caution when given with carvedilol, including:

• amiodarone or other CYP2C9 inhibitors (e.g., fluconazole) 
• cabergoline
• cyclopropane, trichloroethylene, or other anesthetic agents that can depress the heart muscle function 
• cyclosporine
• digitalis glycosides, clonidine, or drugs that can deplete catecholamines (e.g., monoamine oxidase inhibitors such as selegiline) 
• diltiazem, verapamil, or other calcium channel blockers 
• insulin and other hypoglycemic agents (carvedilol may enhance blood glucose lowering effect of these drugs)
• NSAIDs such as meloxicam (may antagonize low blood pressure effect of carvedilol)
• quinidine, fluoxetine, and paroxetine (CYP2D6 inhibitors)
• rifampin
• selamectin (use with carvedilol in dogs that have the MDR1 genetic mutation may increase the risk of adverse effects)
• terbutaline
• theophylline

Is any monitoring needed with this medication?

Routine testing for animals using carvedilol includes:

• blood pressure and heart rate
• resting breathing (respiratory) rate
• ECG and cardiac function test (e.g., echocardiography)
• monitoring the drug concentrations within the blood (plasma) may be recommended
• bloodwork is recommended before starting this medication to assess your pet's general health

At home, monitor for any side effects such as those noted above. If any side effects occur, discontinue use of the medication and contact your veterinarian. 

Your veterinarian will let you know when they want to reassess your pet to ensure the medication is working and not causing side effects. 

How do I store carvedilol?

• Tablets should be stored at controlled room temperature, at 20°C-25°C (68°F-77°F).
• Protect from moisture.
• Store in a tight, light‑resistant container.
• Do NOT store compounded liquids of carvedilol in the refrigerator.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.