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  1. Product Safety Information

Dear Veterinarian Letter advising veterinarians to use Bimasone (flumethasone injectable solution) instead of unapproved drugs in their patients

July 10, 2024

Dear Veterinarian:

In April 2023, the U.S. Food and Drug Administration approved Bimasone (flumethasone injectable solution) for use in horses, dogs, and cats for the various rheumatic, allergic, dermatologic, and other disease states which are known to be responsive to the anti-inflammatory corticoids. The product is now being marketed.

Drug Information

Bimasone is the first generic flumethasone product to receive FDA approval. Bimasone is a corticosteroid drug. It contains the same active ingredient (flumethasone) in the same concentration and dosage form as the approved brand name (reference-listed) drug product, Flucort Solution. Flucort Solution was first approved for use in horses, dogs, and cats on October 21, 1965, and is no longer marketed.

In horses, Bimasone is approved for intravenous, intramuscular, or intra-articular injection and is indicated for musculoskeletal conditions due to inflammation, where permanent structural changes do not exist, such as bursitis, carpitis, osselets, and myositis. It is also indicated for use in allergic states such as hives, urticaria, and insect bites. 

In dogs, Bimasone is approved for intravenous, intramuscular, intra-lesional, or subcutaneous injection. In dogs, Bimasone is indicated for musculoskeletal conditions due to inflammation of muscles or joints and accessory structures, where permanent structural changes do not exist, such as arthritis, osteoarthritis, the disc syndrome (i.e., intervertebral disc disease), and myositis. Bimasone is also indicated in septic arthritis with concurrent administration of appropriate antibacterial therapy. Bimasone is indicated in certain acute and chronic dermatoses of varying etiology to help control the pruritus, irritation, and inflammation associated with these conditions; the drug has proven useful in otitis externa in conjunction with topical medication for similar reasons. Bimasone is indicated for use in allergic states such as hives, urticaria, and insect bites. Bimasone, administered by intravenous injection, is indicated for shock and shock-like states. 

In cats, Bimasone is approved for intravenous, intramuscular, or subcutaneous injection. In cats, Bimasone is indicated in certain acute and chronic dermatoses of varying etiology to help control the pruritus, irritation, and inflammation associated with these conditions.

Bimasone is a prescription animal drug containing 0.5 mg flumethasone/mL and is supplied in 100 mL multi-dose vials. Please refer to the Freedom of Information Summary and package insert for Bimasone for more information. 

FDA-approved drugs have been demonstrated to be safe and effective for their intended use and are required to comply with Current Good Manufacturing Practice (CGMP) that assures the drugs’ identity, strength, quality, including potency and sterility, and purity. When flumethasone is indicated for use in an equine, canine, or feline patient, the FDA strongly encourages veterinarians to use the FDA-approved Bimasone. As with all approved animal drugs, the FDA will monitor and evaluate submitted adverse event reports for Bimasone, which would include monitoring for potential human safety risks associated with administration of the drug. 

Benefits of FDA Approval

The FDA wants to remind you of the benefits of FDA approval. Animal drugs, including generics, are rigorously evaluated by the FDA before approving them. As part of the generic approval process, the drug company must prove to the FDA that:

  • There are data to support that the drug is bioequivalent to the FDA-approved name brand (reference-listed) drug, Flucort Solution. This means that the drug is expected to act the same way in the animal; and therefore, it is presumed 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; 
  • 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.

Safety and Effectiveness of Bimasone Compared to Compounded Forms of Injectable Flumethasone 

Animal drugs compounded from bulk drug substances are not FDA-approved drugs (pioneer or generic). The agency is aware that flumethasone formulations compounded from bulk drug substances may be available through some compounding pharmacies. Unlike FDA-approved Bimasone, compounded and other unapproved formulations of flumethasone have not been evaluated by the FDA for safety or effectiveness and may vary in quality, potency, and bioavailability. It is particularly important for injectable medications, such as flumethasone, to be sterile. 

In contrast to FDA-approved Bimasone, the absorption and bioavailability of compounded formulations of injectable flumethasone are unknown and may be inadequate or variable. Further, while there are many post-approval requirements for sponsors of FDA-approved animal drugs, including the mandatory reporting of adverse drug experience reports, there are no such mandatory reporting requirements for compounded drugs. The FDA encourages veterinarians and animal owners to report adverse drug experiences and product defects associated with animal drugs, regardless of whether they are FDA-approved, and animal devices. More information about how to report information about animal drugs and devices can be found at our website: www.fda.gov/reportanimalae.  

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. For more information, please contact AskCVM@fda.hhs.gov.

Sincerely,

FDA’s Center for Veterinary Medicine
 

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