Previcox vs. Equioxx


Written By: Lisa Nesson, DVM

Written By: Lisa Nesson, DVM

Medication for our horses can get quite costly pretty quickly. Because all horse owners value our horses as companions and athletic partners, we strive to treat them for all of their maladies, but also attempt to keep costs reasonable. While trying to find a balance between these two goals, the practice of using unapproved medication (off-label, less expensive omeprazole pastes), or prescribing prohibited extra-label medication (Previcox instead of Equioxx) has blossomed. Today I’d like to review with you what the difference is between Previcox and Equioxx, why we don’t prescribe Previcox, and what we’re looking for in the future.

What is extra-label drug use?

Extra-label drug use, also known as off-label drug use, is the use of a medication in a way, or for a species, that is not specifically listed on the label. In 1994, Congress passed revisions to FDA legislation which allows veterinarians to use medication in an extra-label fashion under specific conditions. The important specific conditions are as follows:

  1. There is a valid Veterinarian-Client-Patient relationship;

  2. The animal may suffer or die if not treated, and there is no approved animal drug with the appropriate active ingredients, dosage form, concentration, and effectiveness;

  3. The animal drug is only compounded with an approved animal or human drug;

  4. The drug is not on the list of drugs prohibited from extra-label use (ex. chloramphenicol, phenylbutazone, etc.).

This was an important win for veterinarians, since we could now use human and other animal medications if necessary, which was previously illegal. An example of legal extra-label use is offered from the American Veterinary Medical Association here:

“A horse needs to be treated with enrofloxacin based on the culture/sensitivity results of a tendon sheath infection. No horse-labeled enrofloxacin products are available, so the veterinarian could consider treating with the small animal- or bovine-labeled enrofloxacin product.”

Now, let’s get to the heart of the issue.

Previcox and Equioxx

Previcox and Equioxx are both manufactured by Merial. Previcox and Equioxx are both firocoxib, an NSAID used to control pain and inflammation. However, Previcox is a pill that is labeled for use in dogs, and Equioxx is a paste that is labeled for use in horses. Veterinarians and clients have found that Previcox is effective in horses, and significantly less expensive than it’s sister drug, Equioxx. Why the difference in price? This is likely due to the additional work and cost that comes with making firocoxib into a paste form for individual administration. This paste form of Equioxx is important for accurate dosing of firocoxib. Right now, one 57mg tablet of Previcox and one tube of Equioxx both treat a 1,250 lb horse. However, if your horse is 1,000 lb, it’s easy to adjust the dial on the tube of Equioxx to avoid overdosing your horse. With a pill form, it’s very difficult to remove 1/5 of a tablet to treat your horse with the appropriate amount of Previcox.

Frequently, horse owners will ask their veterinarians to prescribe Previcox for their horse in order to see equal efficacy, but a huge cut in price. This is understandable, given the large price difference between the two medications. Unfortunately, if we reread the details of the law from the FDA, it’s clear that this would be a prohibited extra-label use of Previcox. Because there is an approved drug for horses, of equal efficacy, and appropriate concentration, dosage form and active ingredients, it would be prohibited to prescribe Previcox, instead of Equioxx, for a horse.

The Veterinary Dilemma

While equine veterinarians always want to see their patients treated with effective AND cost-effective medication, it would be prohibited to prescribe Previcox to equine patients. This could have multiple ramifications for any equine veterinarian or owner:

  1. Equine insurance companies are unlikely to cover loss of use or mortality of your horse if he has EVER had Previcox;

  2. If your horse experiences a reaction to Previcox, you have no recourse against the manufacturer, since it was used in an extra-label fashion in a horse;

  3. In addition, the FDA and/or the State Licensing Board may take action against any veterinarian prescribing prohibited extra-label drugs, including the suspension of a license.

While all veterinarians want to prescribe cost effective drugs for our patients, by prescribing Previcox to a horse, we would be risking our license to practice and our livelihood.

The Future of Equioxx

Merial is aware of the very really need to have a cost-effective form of Equioxx for horse owners. We hope that we see that medication soon, as we’ll be the first to stock it!