Several studies show there may be and it can affect patient outcomes
Generic medications for the treatment of glaucoma may be significantly different from branded products. These differences may translate to clinical implications, according to Malik Y. Kahook, speaking at the 29th annual Current Concepts in Ophthalmology conference, held in association with the Wilmer Eye Institute and Ophthalmology Times.
Dr Kahook began by saying that the title of his presentation, 'Glaucoma therapy: Living in a generic world', is a topic that is increasingly relevant to all ophthalmologists.
"A relatively high percentage of patients seen in any given ophthalmic practice suffer from glaucoma," said Dr Kahook, professor of ophthalmology and director of clinical research, Rocky Mountain Lions Eye Institute, University of Colorado School of Medicine, Aurora, Colorado, USA. "With the recent introduction of new latanoprost generic formulations, efficacy and safety comparisons with brand-name medications have become a topic of interest for both physician and patient.
The regulatory pathway for generics is much different from that for brand-name medications, Dr Kahook noted. As a patent life nears its end, generic applications go to the FDA. Multiple applications can be submitted at the same time.
"Clinical studies are not required for these generic medications," Dr Kahook said. "The only thing they are required to look at is 'ingredient equivalence', or whether they have the same components in the bottle compared with the brand-name drug.
"While the intended recipe items are the same, the know-how to achieve a stable formulation is not part of the patent life that expires, and is not, typically, shared between companies," he added.
Dr Kahook reviewed several studies, the first of which explored corneal complications associated with topical ophthalmic NSAIDs. Most of the confirmed cases of side effects (53.8%) were associated with a particular generic version that had just come to market (Falcon version). The increase in side effects and adverse events correlated with the introduction of this particular generic on the market.1
"Interestingly, you see a big spike not only in complications and side effects associated with this particular generic, but physicians started noticing what was happening with some of the other formulations, and so you see a spike in complications from several NSAID formulations," Dr Kahook said. "You can tell, however, that the overwhelming majority of patients were under therapy with the new generic version.
"This is one example of why we should pay close attention when new generics come to market," he said. "Of particular relevance to our practice today is the introduction in March 2011 of several generic formulations of latanoprost when Xalatan (Pfizer Inc., New York, USA) went off patent. [Branded latanoprost] had been the most popular topical therapy for [patients with] glaucoma in the US at that point, and many of our patients are being transitioned to the generic formulation. In addition, there are at least two manufacturers from India who are trying to [bring product to] the US."