Trilostane

What is trilostane?

Trilostane (brand names: Vetoryl®, Desopan®, Modrastane®, or Modrenal®) is used for the treatment of hyperadrenocorticism (Cushing’s disease) in dogs and cats, and alopecia X in dogs.

It is used on label to treat hyperadrenocorticism in dogs. It is used off label (extra label) to treat hyperadrenocorticism in cats and alopecia X in dogs. Many drugs are commonly prescribed for off-label use in veterinary medicine.

“Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is trilostane given?

• Trilostane is given orally (by mouth) in the form of capsules. Do not empty the capsule and do not divide the capsules.
• Give trilostane with food, preferably in the morning, if dosing daily.
• Wash your hands after administering the medication.
• Do not handle this medication If you are pregnant or trying to become pregnant.
• Do not stop this drug without consulting your veterinarian.

This medication should take effect within 1 to 2 days.

What if I miss giving my pet the medication or my shipment is late?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once. Do not stop this drug without consulting your veterinarian.

Are there any potential side effects?

Trilostane may cause the following side effects during the first few days of therapy:

• Lethargy
• Vomiting, diarrhea, and lack of appetite

In cats, trilostane may cause the following side effects:

• Lethargy
• Anorexia
• Dulled mental activity

Serious adverse reactions associated with this drug, such as an Addisonian crisis, may occur without warning and could, in rare cases, lead to death. If any of the following signs develop, stop giving trilostane and contact your veterinarian immediately:

• Vomiting
• Diarrhea
• Lethargy
• Shaking
• Increased drinking or urination
• Weakness
• Collapse

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. 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?

DO NOT USE trilostane in pets that:

• Are hypersensitive or allergic to it
• Are pregnant

USE WITH CAUTION in pets that:

• Have kidney or liver impairment
• Are nursing
• Are breeding males (safe use has not been evaluated in male dogs used for breeding)

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with trilostane, including:

• ACE inhibitors (such as benazepril or enalapril)
• Ketoconazole
• Mitotane
• Potassium-sparing diuretics (spironolactone)
• Potassium supplements

Certain medications may interact with trilostane, so be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• At home, monitor closely for any adverse effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.
• Frequent and regular rechecks with your veterinarian are important. Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
• Adrenocorticotropic hormone (ACTH) stimulation tests and other laboratory tests will be needed to monitor for adverse effects, efficacy, and dose appropriateness.

How do I store trilostane?

• Store trilostane capsules in tight, light-resistant containers.
• Store at room temperature, 25°C (77°F), with brief excursions at 15°C–30°C (59°F–86°F) permitted.

What should I do in case of emergency?

In the case of an Addisonian crisis, glucocorticoids should be administered immediately, followed by veterinary care. Your veterinarian should provide you with an emergency supply of glucocorticoids as a precaution.

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. Be prepared to provide information about the product and your pet’s weight and symptoms.