Ask the Vet: Generic vs. brand name drugs

How do generic versions of Adequan and GastroGard stack up to the real deal? Horse Nation’s vet-in-residence Dr. Jen Johnson weighs in.

From Jen:

The USEF stole my thunder. Members in good standing received an email on July 1^st regarding Adequan and its lack of generic. I say they stole my thunder because I had planned, later this summer, to write an article about the differences between generic and brand name drugs. But, I suppose with an intro like that, how can I pass up the opportunity to follow up that mass mailing with my column now.

Anyone who’s been paying attention to mainstream media knows that pharmaceuticals are a huge business. The costs of developing, testing and bring a new drug to market can be in the tens- to hundred of millions of dollars (published estimates range from $55M to $1.2B for human medications). These numbers seem astronomical, but when you consider that of every 25,000 potential chemicals tested in early phases, only one will become an approved drug, you can appreciate the huge costs associated with developing, testing and bring a new medication to market.

Once a company has a promising medication, they fill out a patent application, which, if granted, lasts 20 years in the United States. Most companies fill these out before the drug is actually approved and on the market, to cover their proprietary information during clinical trials. It is possible to read patent information at the US Patent Office’s website (and, if you’re curious, to look up patent expiration dates).

When a drug is nearing the end of its patent protection, other companies may begin trying to replicate the medication to market as a generic form. In order to gain FDA approval, the generic form must behave in exactly the same manner as the brand name form – from dosing to route of administration to duration and mechanism of activity. And this is where other companies can get hung up – sometimes it isn’t the actual active ingredient but the delivery system that causes the generic to fail. For example, GastroGard. The active ingredient is omeprazole. Omeprazole has been around for a long time on the human side – it’s available over the counter and in generic forms. However, the unique physiology of the equine stomach makes the delivery system tricky. Humans and horses do not absorb the drug the same, and most of Merial’s research on GastroGard went into the delivery system to ensure the horses could absorb and use the medication. This is why one should use caution buying “off label” or compounded omeprazole. Sure, it’s the same drug, but the delivery system may be faulty. GastroGard goes off patent in 2015, but there is no guarantee of a less expensive alternative quickly. The delivery system (paste) formula is considered a trade secret, and those are protected indefinitely.

Also, be aware that it is actually illegal for a veterinarian to prescribe something “off label” if a suitable, approved medication exists. If you choose to use off label or compounded medication in your horse, you are potentially risking a higher rate of adverse reactions. Some drug companies will offer financial support for treatment of severe adverse reactions; off label use and compounded medications do not have this same guarantee. So not only are you potentially wasting your money on unproven drugs, you may also be risking greater side effects. It is very important that you thoroughly discuss these ramifications with your veterinary team before making treatment decisions.

Back to the USEF email – the medications being billed as “generic” Adequan range in approval and application. Some are compounded medications; some are approved for other purposes such as wound lavage and joint fluid replacement. They are all the same general class of chemicals in the way that all English saddles are saddles. But would you show up for a jump lesson in your dressage saddle?