Extralabel drug substitution runs afoul of law

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Extralabel use of drugs can give veterinarians effective options in treating patients, but there are limitations veterinarians should be aware of when considering extralabel drug use.

Guidelines set out in the Animal Medicinal Drug Use Clarification Act impose certain restrictions on veterinarians who prescribe approved human and animal drugs for use in ways other than stated on the label. Most of these restrictions apply to use in food animals, but some limitations also pertain to horses and small animals.

The AVMA was recently made aware of questions from veterinarians about treating patients with a drug labeled for use in another species, instead of using a similar drug labeled for use in that species.

Specifically, equine practitioners have been inquiring about the legality of treating horses with Previcox (firocoxib), a nonsteroidal anti-inflammatory drug labeled for use in dogs, instead of Equioxx, which contains the same ingredient but is labeled for use in horses. Both are manufactured by Merial.

The subject has appeared on a number of equine message boards, with equine veterinarians reporting that horse owners are requesting Previcox over Equioxx because of the substantial cost difference between the two products.

According to AMDUCA, however, because Equioxx is labeled for use in horses, the canine product cannot legally be used in an extralabel fashion in horses.

Selecting a canine product over an equine product for any nonmedical reason, including economics, is not acceptable. It is only when an approved equine product has been determined by the attending veterinarian to be clinically ineffective for the labeled use that they can use another animal-approved drug in an extralabel manner.

Some clients or veterinarians have heard that economic concerns are a valid reason to use or prescribe a drug in an extralabel manner—this is true only in that a veterinarian can select an approved human drug to relieve pain and suffering in a nonfood animal even when an identical approved animal drug is available.

The spirit of AMDUCA is to allow veterinarians flexibility in administering drugs that will help relieve animal pain and suffering. The overarching premise of the law is that extralabel use is acceptable when filling a medical need for an animal whose health is threatened. Practitioners who deviate from extralabel use guidelines set out in AMDUCA risk becoming the target of unfavorable actions by the Food and Drug Administration; such actions range from warning letters and regulatory meetings to product seizures, injunctions, and prosecution.

For more information about AMDUCA and extralabel drug use, go here.