Animal & Veterinary

VETORYL (trilostane) Capsules - Veterinarians

Issued: September 11, 2009
Reissued: February 25, 2016

Dear Veterinarian:

In December 2008, the U.S. Food and Drug Administration (FDA) approved VETORYL (trilostane, New Animal Drug Application 141-291) Capsules for the treatment of pituitary-dependent and adrenal-dependent hyperadrenocorticism (Cushing’s disease) in dogs. VETORYL is the first, and so far only, FDA-approved animal drug that contains trilostane as the active ingredient. FDA wants to remind you of the benefits of using approved drugs in your clinic.

Distributed by Dechra, Ltd., VETORYL is a prescription drug and is available in the U.S. in 5, 10, 30, 60, and 120 mg strength capsules. Please refer to the Freedom of Information Summary and package insert for VETORYL for more information about the drug.

Benefits of FDA Approval

FDA rigorously evaluates an animal drug before approving it. As part of the approval process, the drug company must prove to FDA that:

  • The drug is safe and effective for a specific use in a specific animal species;
  • The manufacturing process is adequate to preserve the drug’s identity, strength, quality, and purity; and
  • The drug’s labeling is truthful and not misleading.

FDA’s role does not stop after the agency approves an animal drug. As long as the drug company markets the animal drug, the agency continues to monitor:

  • The drug’s safety and effectiveness. Sometimes, the agency’s post-approval monitoring uncovers safety and effectiveness issues that were unknown at the time of approval;
  • The manufacturing process to ensure quality and consistency are maintained;
  • The drug’s labeling to make sure the information remains truthful and not misleading; and
  • The company’s marketing communications related to the drug to make sure the information is truthful and not misleading.

FDA’s Center for Veterinary Medicine (CVM) is committed to promoting and protecting animal health by ensuring that safe and effective drugs are available for animals. For more information, please contact CVM’s Education & Outreach Staff at 240-402-7002 or


FDA’s Center for Veterinary Medicine

Page Last Updated: 02/05/2018
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