To “compound” a medication is to mix drugs to create a product that is not commercially available (most common in vet med) or to change the delivery (pill to liquid) or flavor (most common in pediatric med). Compounding pharmacies are mostly self-regulated and have little to no external oversight, meaning no one is making sure their products contain what the label claims. This is different from a “generic” medication, which has FDA approval and regulations.
An FDA study showed that 34% of compounded drugs do not meet the potency standards compared to their approved counterparts, and most of these had less than 70% of the active ingredient the label claimed!!! Another recent study presented at last year’s AAEP Convention compared compounded omeprazole products (lower cost versions of Gastrogard for the treatment of ulcers). The compounded forms had less than 63% of the label claim of omeprazole. Meaning, you’d have to give almost two tubes of compounded omeprazole to get the same effect as a single tube of Gastrogard! Additionally the materials used to make these medications do not always come from high quality sources or FDA approved manufacturers making their safety and stability questionable as well.
One of the most common examples of proper compounding in veterinary medicine is pergolide, the medication used to treat Cushing’s Disease in horses. Years ago there was an FDA approved human formulation of the drug that we were able to give to our horses. But more recently they had stopped making this medication for humans and we were forced to use a compounded form to continue treatment on these Cushing’s cases. Because these were not regulated formulations there was always a question as to whether or not there was the right amount of drug in the compound. Was the horse not responding because the diagnosis was wrong or the condition was worsening? Or was it just that we wanted to give 1mg of drug per day but the formulation only contained 0.5mg? Often times finding the right dose for each horse was a guessing game. Thankfully a new FDA-approved equine formulation of pergolide is on the market- Prascend® (Boehringer Ingelheim). Though many people have become used to using the compounded powder or suspension, veterinarians will be switching over to the approved product because we can be confident that it is efficacious and safe for our patients.
While we will always need to compound some drugs in order to have the full arsenal available to keep our animals healthy, when we do compound, we closely research the company and often employ outside labs to verify the concentration and purity. So talk to your veterinarian about compounded medications and beware of online companies offering compounded versions of medications at reduced prices (especially if it is a prescription med and they do not ask for a script!) because you may not be getting what you need!