Mitotane

What is mitotane?

Mitotane, also known as o,p’-DDD (brand names: Lysodren®, Lisodren®) is an anticancer medication that is toxic to adrenal gland cells and is used to treat hyperadrenocorticism (Cushing’s disease) or adrenal gland carcinoma.

Its use in dogs and ferrets to treat adrenal disorders off label (extra label). 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 mitotane given?

• Mitotane is given by mouth in the form of a tablet.
• Give mitotane with food, preferably one high in fat. Your veterinarian may provide you with a high-fat pet food, or you can give the medication with some corn oil, butter, or cheese.

Mitotane is considered a hazardous drug.

• Wear gloves when administering this medication.
• Do not allow the medication to come into contact with your skin, eyes, or mouth.
• Wear gloves when handling your pet’s urine, feces, or vomit, as the drug may be present.
• If you are pregnant, do not handle this medication.

This medication should take effect within 1 to 2 hours; however, effects may not be noted outwardly, and laboratory tests may need to be done to evaluate this medication’s effectiveness.

Improvement in clinical signs should occur within the first 1–2 weeks (e.g., improved eating and drinking habits and a decrease in urination).

What if I miss giving my pet the medication?

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.

Are there any potential side effects?

Mitotane may cause the following side effects:

• Vomiting
• Diarrhea

Serious adverse reactions may occur. If any of the following signs develop, stop giving mitotane and contact your veterinarian immediately:

• Lack of appetite
• Neurologic signs
• Lethargy
• Incoordination
• Weakness
• Yellowing of the skin, gums, or whites of the eyes

Any of these side effects may indicate the need for emergency glucocorticoid supplementation; contact your veterinarian immediately if any side effects occur.

This long-acting medication lasts for at least 4–6 weeks and may last longer in pets with kidney or liver disease.

Are there any risk factors for this medication?

DO NOT use mitotane in pets that:

• Are allergic to it
• Are sick, weak, or frail
• Are pregnant or lactating

USE WITH CAUTION in pets that:

• Have diabetes mellitus
• Have kidney or liver disease
• Have been injured or are undergoing a stressful event like surgery (these pets may be at risk for developing Addison’s disease; during these times, your pet may need to be supplemented with a corticosteroid)

Are there any drug interactions I should be aware of?

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

• Central nervous system (CNS) depressant drugs
• Insulin
• Midazolam
• Phenobarbital
• Selegiline
• Spironolactone

Certain medications may interact with mitotane, 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 there any monitoring that needs to be done with this medication?

• Your veterinarian will monitor your pet to be sure that the medication is working by monitoring clinical effects and performing regular ACTH response tests.
• Your veterinarian may monitor liver and kidney values, blood cell counts, blood sugar levels, and blood electrolytes.
• At home, monitor for any side effects such as those noted above. If any side effects occur, stop using the medication and contact your veterinarian.

How do I store mitotane?

• Store this medication at room temperature, between 59°F and 86°F (15°C and 30°C).
• Protect from light and moisture.

What should I do in case of emergency?

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.