Metoprolol

What is metoprolol?

Metoprolol is a beta-blocker used to treat certain heart rhythm problems and hypertension (high blood pressure) in cats and dogs. It has also been used in the treatment of hypertrophic cardiomyopathy (HCM) in cats. 

It is used off label (extra label) in veterinary medicine. 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 metoprolol?

Metoprolol comes in tablet form. Tablets may be compounded into liquid form.

• Tablets are given orally (by mouth). 
• This medication may be given with or without food. 
• If your animal vomits or acts sick after receiving the drug on an empty stomach, try giving the next dose with food or a small treat. If vomiting continues, contact your veterinarian.  
• Liquid medications must be measured carefully. Contact your veterinarian if you have trouble measuring or giving the medication.
• Give this medication to your pet for the entire time prescribed by your veterinarian, even if it appears that your pet is feeling better.

This medication should take effect within 1 to 2 hours, though effects will not be noticed outwardly.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then wait the recommended amount of time between doses. Do not give the pet two doses at once.

Are there any potential side effects from metoprolol?

Metoprolol may cause the following side effects:

• decreased energy
• diarrhea

The following reactions are rare, but if they occur, contact your veterinarian immediately:

• an allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
• collapse, weakness 
• very slow heart rate
• coughing, wheezing, trouble breathing

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. Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. 

This medication is short-acting, meaning that effects will last less than 24 hours, though effects may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

Metoprolol should NOT BE USED in animals who:

• have severe heart failure, heart block, and/or very slow heart rate
• have asthma
• are in shock
• are allergic to any component of the medication or who are allergic to similar drugs (e.g., propranolol, sotalol)

Metoprolol should be USED WITH CAUTION in animals who:

• have liver disease
• have diabetes mellitus
• have hyperthyroidism

Are there any drug interactions I should be aware of?

Certain medications should be USED WITH CAUTION when given with metoprolol, including: 

• antidiabetic agents (e.g., insulin, glipizide)
• calcium channel blockers (e.g., amlodipine)
• digoxin
• diuretics (e.g., furosemide)
• hydralazine
• lidocaine
• methimazole
• nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., meloxicam)
• phenobarbital

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• Your veterinarian will assess baseline heart function (e.g., rate, rhythm, ECG, blood pressure) before starting this medication and periodically throughout treatment.
• Your veterinarian will schedule follow-up visits for monitoring. In this case, follow your veterinarian’s directions.
• At home, monitor for any abnormal changes. If these occur, discontinue the medication and contact your veterinarian.

How do I store metoprolol?

• Store at room temperature in a tight container.
• Follow storage and expiration recommendations for specially compounded formulas.
• Keep medication out of reach of children and pets.

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. Adverse effects should be reported to the FDA or Health Canada.