Trilostane(Acepron) - Uses, Dosage and Side Effects

Trilostane for dogs and cats is a steroidogenesis inhibitor. It is used in dogs to manage hyperadrenocorticism, commonly known as Cushing's disease or Cushing's syndrome. It may also be used in selected cats with hyperadrenocorticism under veterinary specialist supervision.

In India, Cushing's disease is most frequently diagnosed in middle-aged to senior dogs. Breeds such as Poodles, Dachshunds, Boxers, Beagles, and Labrador Retrievers are more predisposed to pituitary-dependent hyperadrenocorticism, the most common form of the disease.

Trilostane blocks an enzyme called 3β-hydroxysteroid dehydrogenase (3β-HSD), which is a critical step in the adrenal gland's production of cortisol and other steroid hormones. Think of this enzyme as a key production machine in the cortisol factory. Trilostane jams this machine, reducing cortisol output. Because the blockade is reversible when the drug is stopped, Trilostane allows the vet to fine-tune cortisol suppression through dose adjustments based on regular monitoring tests.

Trilostane works through the same basic mechanism in cats, inhibiting 3β-HSD and reducing steroid hormone production in the adrenal cortex. Cushing's disease in cats is uncommon but clinically significant when present, often causing skin fragility, alopecia, and diabetes mellitus that is difficult to regulate with insulin alone. Managing cortisol excess with Trilostane may improve clinical signs and, in some diabetic cats, reduce insulin requirements.

Trilostane dosage for dogs is weight-based and started at a conservative initial dose to avoid excessive adrenal suppression. The dose is adjusted according to clinical response and appropriate cortisol monitoring, which may include ACTH stimulation testing. Give trilostane orally once or twice daily with food, as feeding improves absorption. Do not adjust the dose independently between monitoring appointments. Your vet will guide all dose changes based on clinical signs and scheduled monitoring.

Small dogs require lower total doses because of their body size and should be carefully titrated to the individual patient's response. Regular clinical and hormonal monitoring is important after starting treatment and following dose adjustments. The timing and type of monitoring should be determined by the treating veterinarian rather than by breed or body size alone.

Weight-based starting doses and regular ACTH stimulation testing apply consistently. Medium-sized dogs may show clinical improvement, including reduced water consumption and improved coat quality, within 4 to 8 weeks of reaching an effective dose.

Large dogs require higher total doses because of their greater body weight. Breeds with adrenal-dependent Cushing's disease, where surgical removal of the adrenal tumour is not pursued, may require higher Trilostane doses for adequate cortisol suppression.

Trilostane may be used in selected cats with hyperadrenocorticism, with dosing determined individually by the veterinarian. Cats require careful clinical and laboratory monitoring because feline hyperadrenocorticism and its response to treatment differ from canine disease. Cats with Cushing's disease may have concurrent diabetes mellitus, and insulin requirements can decrease as hypercortisolism is controlled. Any insulin or Trilostane dose adjustments should therefore be made under veterinary supervision with monitoring of clinical signs, blood glucose and other appropriate laboratory parameters.

Cushing's disease in kittens is exceedingly rare. If trilostane is considered for a young cat, treatment should only be undertaken under direct veterinary supervision, with an individualized dose and close monitoring. Do not start trilostane in a kitten without direct specialist guidance.

Side effects range from mild and manageable to potentially life-threatening if adrenal suppression becomes excessive.

Cats may experience lethargy, reduced appetite, vomiting, and signs of adrenal insufficiency if suppression is excessive. Cats with concurrent diabetes mellitus may require less insulin as cortisol excess is controlled, which can increase the risk of hypoglycaemia if insulin doses are not appropriately adjusted. Close glucose monitoring is essential during trilostane dose adjustments in diabetic cats.

Trilostane overdose in dogs causes severe adrenal suppression, presenting as an Addisonian crisis (acute adrenal insufficiency). Signs include profound weakness, vomiting, diarrhoea, collapse, and cardiovascular instability. This is a life-threatening emergency requiring immediate intravenous fluid therapy, glucocorticoid supplementation, and intensive supportive care. Contact your vet or the nearest emergency facility immediately if overdose is suspected or if a dog on trilostane suddenly collapses.

Cats with trilostane overdose may develop severe lethargy, weakness, vomiting, collapse, and hypoglycaemia if concurrently diabetic. Severe adrenal insufficiency and hypoglycaemia can be life-threatening and require emergency veterinary treatment. Do not attempt to manage an acute crisis at home.

Store out of reach of children and pets. People who are pregnant or trying to conceive should avoid handling trilostane unless specifically advised otherwise by a healthcare professional, and anyone handling the medication should follow the product-specific safety instructions.

Contact your vet immediately if your dog or cat on trilostane develops sudden, profound weakness, collapse, complete appetite loss, persistent vomiting or diarrhoea, shaking, or severe lethargy at any point during treatment. These signs may indicate an adrenal crisis from excessive suppression, a condition that requires emergency treatment within hours. Also contact your vet if clinical signs of Cushing's disease worsen, as the dose may need to be increased.

Trilostane is a widely used medical management option for Cushing's disease in dogs and may also be used in selected cats with hyperadrenocorticism, particularly when surgery is not possible or as part of specialist management. Effective treatment depends on starting at a conservative dose, individualising treatment and monitoring the pet's clinical response and laboratory findings, and attending all recommended monitoring appointments. Treatment requirements vary between animals, and dose adjustments may be needed throughout long-term management.