Many people choose a brand over a generic product because they expect to get higher value with a better quality product, consistent robust testing, technical expertise, a longer warranty, the list goes on.
But can a difference exist between animal health products?
Some people assume that if a product contains a certain drug at the same concentration as another product then they must surely be equal. Unfortunately, this has been shown in numerous scientific papers over the years not to be the case.
The manufacturing process, the quality of the active ingredient and excipients (an inert substance added to a product to give the desired consistency) and their long standing stability, among other factors involved in the production of generic formulations, may substantially affect the drugs absorption which in turn could affect drug effectiveness. In fact, factors related to the quality of the active ingredient have been associated with therapeutic failure of generic rafoxanide formulations against Haemonchus contortus in sheep (Van Wyk et al., 1997). Furthermore, products containing subtherapeutic amounts of the active ingredient, and/or formulation quality related absorption failures may increase the risk of selection and spread of drug resistant bugs (Newton et al., 2010).
A paper recently published in the New Zealand Veterinary Journal (Oritz, et al., 2014) found that only one out of four generic triclabendazole containing products could be considered as equivalent to the pioneering product that they were supposedly emulating.
In another paper, three generic albendazole containing products were tested against the pioneering product (Suarez et al., 2011). All three generic products showed lower drug concentrations in the blood stream compared to the reference (RF) pioneering product. This measure of blood concentration is known to correlate to the level of drug concentration achieved in the parasite. The authors in this paper concluded that the differences were related to different drug formulations rather than the active ingredient. The ability of the drug to dissolve in the acidic stomach is a critical factor limiting the absorption of the active ingredient. Therefore different issues related to the quality of the manufacturing procedures (micronized, particle size, surface, crystal structure of the active substance, type of excipients etc.) applied to elaborate the final formulation may drastically affect the amount of active drug available to be absorbed in the gut. The authors went on to conclude that ‘some drastic pharmacokinetic differences were observed’ between the generic formulations and the pioneering product.
Although generic drenches may appear to be able to save you a few bucks, the most expensive drench you’ll buy is one that doesn’t work.
Thanks to Merial for the use of this article.
