Buyer Beware: Custom Drugs Not Always Effective

When it comes to treating your horse's illness, would you rather use a more expensive FDA-approved drug that passed stringent federal clinical trials and studies for efficacy and safety, or use a cheaper compound blended by a pharmacist that contains some of the primary ingredients in different formulations and amounts, follows no government guidelines, and meets no standards demonstrating the compound is effective? That's the crux of drug compounding: The same ingredients in different formulations may yield different, possibly less desirable results.

Custom Drugs

Drug compounding occurs when a pharmacist prepares a customized medication for a particular patient by combining bulk ingredients or several different preparations to form a special, customized formulation. This is primarily done when an FDA-approved product is not available, an existing drug contains properties that cause allergies in the patient, or an existing drug needs to be administered by a different means, i.e., orally instead of intravenously.

Compounded drugs can play an especially important role in the veterinary world. "In veterinary medicine, we treat a lot of different species and sizes of animal, and there may not be a product approved for use for that particular species or formulated for that particular size of animal," notes Cynthia-Kollias Baker, DVM, PhD (cardiovascular pharmacology), Diplomate American College of Veterinary Clinical Pharmacology, equine clinical pharmacologist at the University of California, Davis. "Consequently, there is a need for pharmacists to specialize or customize a drug for a particular animal."

The individual pharmacist determines the precise amount of each ingredient that goes into the compounded product, so a compound product created by one pharmacy may likely vary from one created by another. These compounded products do not require FDA approval, and while the pharmacies are overseen and regulated, the compound is neither analyzed nor checked for quality or efficacy, Dr. Kollias-Baker says. Because these compounds do not undergo efficacy trials and studies, as do FDA-approved drugs, they usually are cheaper to purchase.

Occasionally, a veterinarian requests a compounded drug when an existing product for treating a disease in that species already exists, usually because the client wants a cheaper alternative to the FDA-approved product.

The results can be mixed. Explains James Orsini, DVM, Diplomate American College of Veterinary Surgeons, University of Pennsylvania, New Bolton Center, "There are no guidelines or accountability with a compounded drug: That's the problem. There is no way to know if the compound contains the correct concentrations of ingredients. There is no way to assure that the drug is absorbed into the system before it breaks down. There is no way the pharmacist can test the compound to make sure the drug is going to be effective." The client could very well end up paying for something that doesn't work as well or at all.

Penny Wise, Pound Foolish

The practice of drug compounding has recently become a hot activity in the veterinary community. Some practitioners and clients in the racehorse and performance horse industries have become interested in compounding cheaper, would-be imitations of GastroGard® the only FDA-approved treatment for gastric ulcers in horses. Dr. Kollias-Baker stated, "Omeprazole, the primarily ingredient in GastroGard®, has been used for ulcers for years. But one of the limiting factors for omeprazole is its absorption: It is very labile in the stomach, as stomach acid can degrade the drug, rendering it ineffective. Merial has developed a sophisticated formulating process that protects the drug from this acid degradation and allows it to be absorbed.

Knowing the type of chemistry that Merial put into GastroGard® and the years it took them to develop these particular formulations, I find it hard to believe that a compounding pharmacy could put in the same amount of effort and chemistry knowledge into their compounded product so as to make it equally protected from the acid in the stomach as GastroGard®."

Dr. Kollias-Baker is conducting studies, underwritten internally by the K.L. Maddy Equine Analytical Chemistry Laboratory, to compare the absorption of a compounded omeprazole product and GastroGuard®. Half the study group was administered GastroGard®; half received a compounded formulation. "Pilot results showed that horses administered GastroGard® had readily detectable amounts of omeprazole in their serum, meaning the drug was absorbed to a significant degree and detected in the blood stream." In contrast, the compounded product at the recommended bottle dosage was either undetectable in blood serum or was only detected at one time-point, indicating that little or none of the product was being absorbed. If the omeprozole is not absorbed it is unlikely to be effective for treating ulcers.

In fact, an analysis of compounded omeprazole products, conducted by Merial, found omeprazole values ranged between 6% and 74% of their labeled values, with an average of less than 30% omeprazole content, compared to more than 90% of omeprazole contained in GastroGard®.

But many veterinarians, including Dr. Orsini, do not need study results to demonstrate the ineffectiveness of compounded GastroGard®. In seeing equine ulcer patients at New Bolton Center, Dr. Orsini found the horses that were given a compounded product by the referring veterinarian still had ulcers that were as severe as if they had been receiving no medication at all. "In contrast, the horses I've examined that had been on GastroGard® for the prescribed time, with few exceptions, had ulcers that were totally gone or very mild."

Bottom Line

When there is no specific equine drug available for treating a particular disease, drug compounds are often the only alternative. But when it comes to choosing between an approved equine drug that's been proven to work or taking a chance on a cheaper, unproven compound, the horse owner may jeopardize their horse's health by opting for a compounded medication.

Concludes Dr. Kollias-Baker, "There is a role for compounding: They do a fabulous job in situations where we really need to get a product synthesized in order to treat a particular patient with a particular disease. But consumers have to be very cautious that they are not using them in lieu of using an effective, FDA-approved product simply to save money and to risk sacrificing their horse's health."