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December 20, 2022

Dear Pharmacy Professional:

In December 2022, the U.S. Food and Drug Administration (FDA) approved Zycosan (pentosan polysulfate sodium) injection for the control of clinical signs associated with osteoarthritis in horses. 

Pentosan polysulfate sodium products should not be imported from other countries for use in horses. Also, please be aware that any compounded animal drug, including a compounded pentosan polysulfate sodium product, is not FDA-approved. This means the FDA has not evaluated the safety and effectiveness of the compounded drug or the adequacy of the manufacturing process.

Drug Information

Zycosan is a prescription animal drug containing 250 mg pentosan polysulfate sodium/mL and is intended for intramuscular injection. Zycosan is approved at a dosage of 3.0 mg/kg of body weight (1.4 mg/lb) administered once per week for four weeks. Zycosan is provided in single-use vials. Vials do not contain a preservative and should be discarded after use. Please refer to the Freedom of Information Summary and package insert for Zycosan for more information.

Benefits of FDA Approval

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

• There are data to support that the drug is safe and effective for a specific use in the intended 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.

The 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 that the identity, strength, quality, and purity of the drug 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.

The FDA’s Center for Veterinary Medicine (CVM) is committed to promoting and protecting animal health by ensuring safe and effective drugs are available for animals. If you have any questions or comments, please contact [email protected].

Sincerely,

FDA’s Center for Veterinary Medicine