Prilactone is available as three different strengths 10mg, 40mg or 80mg tablets for dogs.

Prilactone tablets are for the use in combination with standard therapy (including diuretic support, where necessary) for the treatment of congestive heart failure caused by valvular regurgitation in dogs.

Prilactone® 10 mg Tablets for dogs - White, with a slight brownish mottling, bisected oval tablet of 10 mm length, containing spironolactone 10 mg.

Prilactone® 40 mg Tablets for dogs - White, with a slight brownish mottling, oval tablet of 17 mm length with three parallel break-lines, containing spironolactone 40 mg.

Prilactone® 80 mg Tablets for dogs - White, with a slight brownish mottling, oval tablet of 20 mm length with three parallel break-lines, containing spironolactone 80 mg.

2 mg of spironolactone per kg of bodyweight once day. The product should be administered with food. Do not use in animals used for, or intended for use in breeding. Do not use the product in dogs suffering from hypoadrenocorticism, hyperkalaemia or hyponatraemia. Do not administer spironolactone in conjunction with NSAIDs to dogs with renal insufficiency.

Kidney function and serum potassium levels should be evaluated before initiating combined treatment with spironolactone and ACE inhibitors. Unlike in humans, an increased incidence of hyperkalaemia was not observed in clinical trials performed in dogs with this combination. However, in dogs with renal impairment regular monitoring of renal function and serum potassium levels is recommended as there may be an increased risk of hyperkalaemia.

Dogs treated concomitantly with spironolactone and NSAIDs should be correctly hydrated. As spironolactone has an antiandrogenic effect, it is not recommended to administer the product to growing dogs. As spironolactone undergoes extensive hepatic biotransformation, care should be taken when using the product to treat dogs with hepatic dysfunction.

Special precautions to be taken by the person administering the veterinary medicinal product to animals. Prilactone may cause skin sensitisation: persons known to be allergic to spironolactone should not handle the product. Wash hands after use. In the event of accidental ingestion, seek medical advice immediately and show the package leaflet or the label to the physician.

A reversible prostatic atrophy is often observed in entire male dogs. Do not use during pregnancy and lactation.

In clinical studies, Prilactone® was co-administered with furosemide and pimobendan without evidence of associated adverse reactions.

Spironolactone decreases digoxin elimination and hence raises digoxin plasma concentration. As the therapeutic index for digoxin is very narrow, it is advisable to monitor closely dogs receiving both digoxin and spironolactone.

The administration of either deoxycorticosterone or NSAIDs with spironolactone may lead to a moderate reduction of the natriuretic effects (reduction of urinary sodium excretion) of spironolactone. Concomitant administration of spironolactone with ACE-inhibitors and other potassium-sparing drugs (as angiotensin receptor blockers, ß-blockers, calcium channels blockers, etc.) may potentially lead to hyperkalaemia.

Spironolactone may cause both induction and inhibition of cytochrome P450 enzymes and could therefore affect the metabolism of other drugs utilizing these metabolic pathways.

In case of an accidental massive ingestion by a dog, there is no specific antidote or treatment. It is therefore recommended to induce vomiting, lavage the stomach (depending on risk assessment) and monitor electrolytes. Symptomatic treatment, e.g., fluid therapy, should be provided.

Keep out of reach and sight of children. For animal treatment only. This veterinary medicinal product does not require any special storage conditions. Partially used tablets should be stored in the original blister pack. Spironolactone and its active metabolites (including 7a-thiomethyl-spironolactone and canrenone) act as specific antagonists of aldosterone, and exert their effects by binding competitively to the mineralocorticoid receptor located in the kidneys, heart and blood vessels.

Spironolactone is a natriuretic drug (historically described as a soft diuretic). In the kidney, spironolactone inhibits the aldosterone-induced sodium retention leading to increase in sodium and subsequently water excretion, and potassium retention. The renal effects of spironolactone and its metabolites lead to a decrease in extracellular volume and consequently in a decrease of cardiac preload and left atrial pressure. The result is an improvement in heart function.

In the cardiovascular system, spironolactone prevents the detrimental effects of aldosterone. Although the precise mechanism of action is not yet clearly defined, aldosterone promotes myocardial fibrosis, myocardial and vascular remodelling and endothelial dysfunction. In experimental models in dogs, it was shown that long term therapy with an aldosterone antagonist prevents progressive left ventricle dysfunction and attenuates left ventricle remodelling in dogs with chronic heart failure.

In a clinical study investigating the survival time in dogs with congestive heart failure, there was a 65% reduction in the relative risk of mortality at 15 months in dogs treated with spironolactone in combination with standard therapy compared to dogs treated with standard therapy alone (mortality was classified as death or euthanasia due to heart failure).

When used in combination with ACE-inhibitors, spironolactone may counteract the effects of “aldosterone escape”. A slight increase in aldosterone blood levels may be observed in animals on treatment. This is thought to be due to activation of feedback mechanisms and is without adverse clinical consequence. There may be a dose related hypertrophy of the adrenal zona glomerulosa at high dose rates