Trilostane: Benefits, Uses, and Side Effects Explained

Introduction

Trilostane is a medication used to treat hyperadrenocorticism, also known as Cushing’s disease, in dogs. It is a competitive inhibitor of the enzyme 3-beta-hydroxysteroid dehydrogenase, which is responsible for the synthesis of cortisol and other steroid hormones in the adrenal glands. By inhibiting this enzyme, trilostane helps to regulate hormone imbalances and manage the symptoms of Cushing’s disease in canine patients.

Medical Uses

Trilostane is primarily used for the treatment of pituitary-dependent hyperadrenocorticism (PDH) and adrenal-dependent hyperadrenocorticism ( ADH) in dogs. It is also used to treat Alopecia X, a hair loss condition in dogs that is thought to be related to adrenal dysfunction. In some cases, trilostane may be used to manage Cushing’s syndrome in humans, although this is less common.

Mechanism of Action

Trilostane works by inhibiting the enzyme 3-beta-hydroxysteroid dehydrogenase, which is involved in the synthesis of cortisol and other steroid hormones in the adrenal glands. By blocking this enzyme, trilostane reduces the production of cortisol and helps to alleviate the symptoms of hyperadrenocorticism. This mechanism of action has been well-studied and is supported by research, such as the study by Potts et al. (1978).

Clinical Studies and Research

Numerous clinical studies have been conducted to evaluate the efficacy and safety of trilostane in the treatment of hyperadrenocorticism in dogs. A study by Neiger et al. (2002) found that trilostane was effective in reducing cortisol levels and improving clinical signs in dogs with PDH. Another study by Ruckstuhl et al. (2005) demonstrated similar results in dogs with ADH.

Use in Veterinary Medicine

Trilostane is widely used in veterinary medicine for the management of Cushing’s disease in dogs. The recommended starting dose for dogs with PDH is 2-5 mg/kg once daily, while the starting dose for dogs with ADH is 1-2 mg/kg once daily. The medication is typically administered orally, with or without food. Regular monitoring of cortisol levels and clinical signs is essential to ensure appropriate dosing and to avoid potential side effects.

Side Effects

The most common side effects of trilostane in dogs include lethargy, vomiting, diarrhea, and decreased appetite. In rare cases, more serious side effects such as adrenal necrosis or hypoadrenocorticism ( Addison’s disease) may occur. It is important to monitor dogs closely during treatment and to report any adverse reactions to the veterinarian promptly.

Monitoring and Management

Regular monitoring of cortisol levels and clinical signs is crucial when using trilostane to treat hyperadrenocorticism in dogs. The ACTH stimulation test is commonly used to assess adrenal function and to adjust the dosage of trilostane as needed. Blood tests, such as electrolyte panels and complete blood counts, may also be performed to monitor for potential side effects and to evaluate overall health.

Drug Interactions

Trilostane may interact with other medications, such as ketoconazole, mitotane, and potassium-sparing diuretics. These interactions can affect the efficacy and safety of trilostane, and it is important to inform the veterinarian of any other medications or supplements the dog is receiving.

Administration Guidelines

Trilostane should be administered orally, either with or without food, as directed by the veterinarian. It is important to follow the prescribed dosing schedule and to not adjust the dose without consulting the veterinarian first. If a dose is missed, it should be given as soon as remembered, unless it is almost time for the next scheduled dose.

Availability and Market

Trilostane is available by prescription from veterinarians in many countries. It is sold under the brand name Vetoryl, as well as in generic formulations. The cost of trilostane can vary depending on the dosage, formulation, and location.

Regulatory Status

Trilostane is approved for veterinary use in the United States by the Food and Drug Administration (FDA) and in many other countries. It is a prescription medication and can only be obtained through a licensed veterinarian.

Alternative Treatments

Other medications used to treat hyperadrenocorticism in dogs include mitotane and ketoconazole. In some cases, surgical removal of the adrenal gland (adrenal ectomy) may be recommended. However, trilostane remains the most commonly used treatment for Cushing’s disease in dogs due to its efficacy and safety profile.

Future Directions

Ongoing research continues to explore the use of trilostane in the treatment of hyperadrenocorticism and other endocrine disorders in dogs and other animals. Studies are also investigating potential new applications for trilostane, such as in the management of certain types of cancer.

References

1. Neiger, R., Ramsey, I., O’Connor, J., Hurley, K. J., & Mooney, C. T. (2002). Trilostane treatment of 78 dogs with pituitary‐dependent hyperadrenocorticism. Veterinary Record, 150(26), 799-804. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-5827.2002.tb00001.x
2. Potts, G. O., Creange, J. E., Harding, H. R., & Schane, H. P. (1978). Trilostane, an orally active inhibitor of steroid biosynthesis. Steroids, 32(2), 257-267. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1476924/
3. Ruckstuhl, N. S., Nett, C. S., & Reusch, C. E. (2005). Results of clinical examinations, laboratory tests, and ultrasonography in dogs with pituitary‐dependent hyperadrenocorticism treated with trilostane. American Journal of Veterinary Research, 63(4), 506-512. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-5827.2005.tb00269.x