This is where compounding pharmacies come in. Compounding a drug means that a new medication is created by combining or altering ingredients. It can be a way to customize a drug for an individual's needs, or create a drug that does not otherwise exist. This can be done by creating the drug from "bulk" (raw) materials or by altering a pre-existing formulation. If a drug exists, altering it can be as simple as making a liquid from a tablet, or adding a flavoring agent. Think of baking a cake from scratch (flour, eggs, milk, etc) versus using a boxed mix where most of the ingredients are premeasured for you. In general, using a boxed mix gives you a more consistent product, but if that box doesn't exist, you must make it from scratch.
Since compounding pharmacies aren't regulated at the federal level (they are licensed and regulated by the state), questions regarding drug concentrations, potency, and shelf life have arisen. Drugs that are approved by the FDA undergo rigorous testing with regards to concentration and stability (it takes an average of 12 years to get a human drug approved!). After this testing, drugs are labeled with an expiration date. Compounded drugs, by law, do not have expiration dates; however they do have "Discard after" dates. These discard after dates usually have nothing to do with concentration studies and tend to merely be recommendations by the pharmacy.
As we said, for the past few years, pergolide has been available only as a compounded drug. And it has worked well in the hands of veterinarians during that time. It has been available as a liquid or as a flavored powder for ease of administration. (What horse doesn't prefer peppermint flavoring covering their meal?) The problem is that there is no guarantee of how long it will last or what the actual concentration of the drug is. A study was performed looking at the stability of compounded pergolide over a 35 day period and it revealed a significant drop in drug concentration over that time. Not only that, but the original concentrations of these drugs were not always exactly as labeled. Prascend® will be available as a tablet which can be purchased in large quantities. It's shelf life will far exceed that of a compounded drug. It is supposedly easily dissolved in water, but the manufacturers are recommending that it not be crushed.
How will this affect you and your horse? The fact is we are not 100% sure at this time. When an FDA-approved product exists, we are required to use that product instead of a compounded one. There are instances where we are able to compound a new formulation (such as a paste) from the approved product, for ease of administration. The production of a powder form of pergolide may or may not be possible. What we do know is that this drug is likely going to cost a bit more. The prices that we have seen are slightly higher than what we pay for the compounded drug, but you must remember that this drug cost millions of dollars to develop.
While it may take some getting used to, we feel that the FDA approval of Prascend® is a good thing for the horse industry. It is a stable drug with a guaranteed concentration. Since it is a lifetime drug, the convenience of being able to buy a six month supply versus remembering to refill a prescription monthly is something to look forward to. And that means you don't have to talk to that pesky vet as much! Not a bad trade off for a few extra dollars a month, eh?