By Rania Gollakner, BS, DVM, MPH

What is sprironolactone?

Spironolactone (brand names: Aldactone®, Prilactone®, Tempora®, CaroSpir®) is a potassium sparing diuretic used as an adjunctive therapy to treat congestive heart failure. It has also been used to treat fluid accumulation in the abdomen and may be effective for treating kidney disease or high blood pressure.

Its use in cats and dogs to treat heart failure and other cardiovascular conditions 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 spironolactone given?

Spironolactone is given by mouth in the form of a tablet. It may also be compounded into a liquid form; measure liquid forms carefully. It can be given with or without food; however, if your pet vomits when dosed on an empty stomach, give future doses with food. Allow your pet access to clean and plentiful water at all times while giving this medication. Because this medication causes more frequent urination, do not give the last dose of the day close to bedtime to reduce the need to let your pet out to urinate.

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

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

The most common side effects include increased drinking and urinating, mild decreases in energy, mild electrolyte imbalances, or vomiting and diarrhea. Other possible side effects include breast tissue growth in males. Serious side effects include facial itchiness, rash/skin sores, persistent vomiting or diarrhea, severe tiredness, fast heartbeat, difficulty walking, collapse, loss of balance, lack of appetite, or lack of urinating.

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?

Spironolactone should not be used in pets that are allergic to it or in pets with elevated potassium levels, Addison’s disease, acute kidney failure, or significant kidney disease. Do not use in pets that are not urinating or in pets that may be used for breeding. It should be used cautiously in pets with liver disease, that are pregnant or lactating, or have uncontrolled diabetes or other conditions that cause blood electrolyte imbalances.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with spironolactone: digoxin, mitotane, neuromuscular blockers, other potassium-sparing diuretics, potassium supplements, or salicylates. 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?

Blood electrolytes and kidney values (BUN, creatinine) will be measured prior to your pet starting this medication, 1-2 weeks after starting, and then monitored every 2 months thereafter. Blood pressure, weight, and hydration may also need to be monitored. Your veterinarian may monitor your pet to be sure that the medication is working by watching for swelling. Monitor your pet at home for serious side effects.

How do I store spironolactone?

Store the tablets at room temperature (68°F to 72°F or 20°C to 22°C) and protect from light and moisture. Store compounded liquids according to the label.

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.

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