Animal & Veterinary

FACTREL (gonadorelin hydrochloride) Injection - Veterinarians

Issued: July 2, 2013
Revised: April 24, 2015
Reissued: November 6, 2015
Revised: March 2, 2016

Dear Bovine Veterinarian:

In June 2013, FDA approved the second gonadotropin releasing hormone (GnRH) product, FACTREL Injection, for estrous synchrony in lactating dairy cows. FACTREL Injection (New Animal Drug Application 139-237) is a sterile injectable solution of gonadorelin hydrochloride, and when used with LUTALYSE Injection (dinoprost tromethamine injection) as part of a synchronization regimen, the drug can be used to synchronize estrous cycles to allow for fixed-time artificial insemination in lactating dairy cows. FDA wants to remind you of the benefits of using approved drugs in your practice.

Manufactured by Zoetis Inc., FACTREL Injection is a prescription drug available in 20 mL multi-dose vials. The concentration is 50 mcg gonadorelin (as gonadorelin hydrochloride) per mL of solution. Please refer to the Freedom of Information Summary and package insert for FACTREL Injection 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.

For a drug intended to be used in food-producing animals, FDA’s approval process also ensures that food products, such as milk and meat, from treated animals are safe for people to eat.

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.

Other Gonadorelin Products

Five gonadorelin (GnRH) products are FDA-approved to treat cystic ovaries in dairy cows, but only three are also FDA-approved for use with another drug for synchronizing estrous cycles in lactating dairy cows: GONABREED, FACTREL Injection, and FERTAGYL.

FDA-approved GnRH Products for Use with Another Drug for Estrous Synchrony

ManufacturerZoetis Inc.Parnell Technologies Pty. Ltd.Intervet, Inc.
Active IngredientGonadorelin hydrochlorideGonadorelin acetateGonadorelin acetate
For Estrous Synchrony, Use With:LUTALYSE Injection (dinoprost tromethamine injection)Cloprostenol sodiumESTRUMATE (cloprostenol injection)
Species/ClassLactating dairy cows Lactating dairy cows and beef cows  Lactating dairy cows

Other than the three uses listed in the table above, it is illegal to use GnRH products in cattle with another drug for estrous synchrony.

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: 03/03/2016
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