We commonly think all that’s important is the active ingredient and how much is in the tablet when we buy a bottle of Advil®. The label lists the amount and active ingredient, stating 200 mg of ibuprofen per tablet. However, Advil®, as well as all other drugs, is far more complex. The drug is everything in the tablet recipe including the active ingredient, the preservatives, the outer coating, etc. It includes the quality, purity and strength of the ingredients and how they are put together. In addition, it includes the container, the box, the instructions, the advertising, etc. It includes the efficacy and safety of the product as it’s manufactured.
Typically, the most difficult and costly part of an FDA (Food and Drug Administration) approval is getting the recipe and manufacturing correct so that the tablet contains what the label states it contains for the shelf life of the drug. It is so difficult to get this right that the FDA allows drugs, with few exceptions, to contain between 90 to 105% of the stated ingredients. So on that basis, a drug that states it contains 100 mg per tablet of active ingredient may actually contain somewhere between 90 and 105 mg. In addition, the shelf-life testing (how long the product can sit without being used and still deliver an effective dose) costs hundreds of thousands of dollars for a single drug container size. That fee is doubled if two different pill sizes are manufactured.
What is a compounded drug?
There are two important types of compounded drugs:
One type involves an FDA approved drug as the starting point. The drug is then altered prior to giving the drug to a patient. For example, an FDA approved tablet of bute (phenylbutazone) may be crushed and mixed with molasses before being administered to a horse. The act of changing the drug from the original format makes this a compounded drug. This and all similar compounding could destroy the effect of the drug and thus should be carried out according to your veterinarian’s instructions.
The second type of compounding is called ‘bulk chemical compounding’. The starting point in this form of compounding is a chemical powder labeled as a drug’s active ingredient, sourced from a variety of countries. This chemical is prepared and sold as a compounded drug. Unfortunately, there is no FDA oversight in the manufacturing of compounded drugs made from bulk compound chemicals to ensure accuracy of the label. These products are far less expensive than FDA approved drugs because they did not incur the expense of an FDA approval, nor do they have expenses associated with continuous FDA oversight of the product after they are approved. Without FDA scrutiny and oversight, one cannot be certain of a drug’s purity, strength and shelf life stability.
When should I use a compounded drug?
You should only use a compounded drug by the order of a veterinarian and only in cases where an FDA approved drug does not exist or is deemed unusable for your horse’s specific case. Work closely with veterinarians who have made an effort to scrutinize the compounding pharmacy that they recommend.
What about compounded drugs for food or production animals?
It is strictly prohibited to use any compounded drugs for food animals with the exception of certain listed antidotes.
Joe Bertone, DVM, MS, DACVIM (Large Animal Internal Medicine)
Professor Equine Medicine
College of Veterinary Medicine
Western University of Health Sciences