By Rania Gollakner, BS, DVM, MPH

What is captopril?

Captopril (brand names: Capoten®, Captril®) is an angiotensin-converting enzyme (ACE) inhibitor. It is used to treat congestive heart failure and high blood pressure. Newer ACE inhibitors that are FDA-approved for animal use are more common, but captopril is still available.

Its use in cats and dogs to treat high blood pressure and congestive heart failure is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is captopril given?

Captopril is given by mouth in the form of a tablet. Give on an empty stomach. Allow access to fresh drinking water at all times while giving this medication.

This medication should take effect within 1 to 2 hours; however, effects may not be visibly obvious and therefore laboratory tests may need to be done to evaluate this medication’s effectiveness.

What if I miss giving my pet the medication?

Give the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects include vomiting, diarrhea, or lack of appetite. Serious side effects include persistent vomiting and/or diarrhea, weakness, skin reactions, infections, kidney damage, high potassium levels, or fever.

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

Are there any risk factors for this medication?

Do not use captopril in pets that are allergic to it or other ACE inhibitors. It should be used cautiously in pets with kidney disease, dehydration, low sodium levels, low blood pressure, blood abnormalities, or vessel disease. Captopril should be used cautiously, if at all, in pregnant or nursing pets.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with captopril: anesthetics, antacids, antihypertensive agents, baclofen, buspirone, cabergoline, cimetidine, corticosteroids, darbepoetin alfa, digoxin, diphenhydramine, diuretics, doxepin, oral glycerin, heparin, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, potassium, probenecid, sildenafil, or vasodilators.

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

Is there any monitoring that needs to be done with this medication?

A complete blood count, blood electrolyte levels, kidney values, and urinalysis will be monitored regularly. Your veterinarian may monitor your pet to be sure that the medication is working; if treating for congestive heart failure, breathing rate, radiographs (X-rays), and cough may be monitored; If treating high blood pressure, then blood pressure will be monitored regularly.

How do I store captopril?

Store the tablets at room temperature, below 86°F (30°C), in a tight container, protected from light.

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.

Related Articles