Spironolactone
Also known as: Aldactone, Aldactazide, Cardalis, Prilactone
* **Administration:** Give this medication **with food**, as it significantly increases how well the drug is absorbed into the body. * **Potassium Warning:** Because this drug helps the body retain potassium, **do not give your pet potassium supplements** or switch to a high-potassium diet unless specifically instructed by your veterinarian. * **When to Call the Vet:** Notify your veterinarian if your pet experiences severe or persistent vomiting, diarrhea, loss of appetite, or extreme lethargy/weakness. * **For Cat Owners:** A small percentage of cats (especially Maine Coons) may develop severe facial itchiness, scabs, or dermatitis while on this drug. If you notice your cat scratching its face excessively, contact your veterinarian.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- As a diuretic in CHF (when furosemide and ACE inhibitors alone do not control fluid accumulation)
- As a diuretic in CHF (when serum potassium is low)
- For adjunctive treatment of hypertension
- For adjunctive treatment of hypertension (Step 3 drug)
- For adjunctive treatment of primary hyperaldosteronism
- Congestive heart failure, ascites, hyperaldosteronism
- As a diuretic in CHF (when furosemide and ACE inhibitors alone do not control fluid accumulation)
- As a diuretic in CHF (with other diuretics when hypokalemia is an issue)
- As a diuretic in CHF (to allow further reduction of furosemide dose)
- For treating ascites (using fixed dose combination with hydrochlorothiazide)
- For treating ascites (caused by right-sided heart failure)
How it is given
Possible side effects
- Facial dermatitis (notably reported in Maine Coon cats)
- Hyperkalemia
- Hyponatremia
- Dehydration
- Increased BUN and mild acidosis (in patients with renal impairment)
- Gastrointestinal distress (vomiting, anorexia)
- CNS effects (lethargy, ataxia)
- Endocrine changes (anti-androgenic effects, e.g., gynecomastia in humans, feminization of male fetuses)
- Hyponatraemia
- Hyperkalaemia
- Reversible prostatic atrophy (in entire male dogs)
- Severe ulcerative facial dermatitis (in Maine Coon cats)
- Hepatotoxicity (reported in humans)
Cautions & contraindications
- Hyperkalemia
- Addison's disease (hypoadrenocorticism)
- Anuria
- Acute renal failure
- Significant renal impairment
- Hypoadrenocorticism
- Hyperkalaemia
- Hyponatraemia
- Concurrent use with NSAIDs in animals with renal insufficiency
- Pregnancy
- Lactation
- Animals intended for breeding
- > **Hepatic & Renal Caution:** Use cautiously in patients with hepatic disease (though often used to treat ascites). Use in patients with renal impairment may lead to hyperkalemia. > **Reproductive Safety:** FDA Category D for pregnancy. Spironolactone and its active metabolites cross the placenta and can cause feminization of male fetuses. Canrenone (active metabolite) is excreted in breast milk; use with caution in nursing animals.
Drug interactions
- Digoxin: Spironolactone may increase the half-life of digoxin; enhanced monitoring of digoxin serum levels is warranted. May also cause falsely elevated digoxin values if using a radioimmune assay (RIA).
- Mitotane: Spironolactone may mute the effects of mitotane if given concurrently; monitor carefully.
- Neuromuscular blockers, non-depolarizing: Possible increase in neuromuscular blockade effects.
- Potassium-sparing diuretics (e.g., triamterene): Increased risk of hyperkalemia.
- Potassium supplements: Increased risk of hyperkalemia.
- Salicylates (e.g., Aspirin): Spironolactone's diuretic effects may be decreased if administered concomitantly.
- Thiazide diuretics: Potentiates diuretic effects
- Loop diuretics: Potentiates diuretic effects
- ACE inhibitors: Increased risk of hyperkalaemia (though generally safe to use concurrently in practice; monitor potassium)
- NSAIDs: Increased risk of hyperkalaemia and nephrotoxicity
Frequently asked questions
What is Spironolactone used for in pets?
* **Administration:** Give this medication **with food**, as it significantly increases how well the drug is absorbed into the body. * **Potassium Warning:** Because this drug helps the body retain potassium, **do not give your pet potassium supplements** or switch to a high-potassium diet unless specifically instructed by your veterinarian. * **When to Call the Vet:** Notify your veterinarian if your pet experiences severe or persistent vomiting, diarrhea, loss of appetite, or extreme lethargy/weakness. * **For Cat Owners:** A small percentage of cats (especially Maine Coons) may develop severe facial itchiness, scabs, or dermatitis while on this drug. If you notice your cat scratching its face excessively, contact your veterinarian.
Is Spironolactone safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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