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Generic 'equivalents'?
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This three-part blog series has focused on generic medications in ophthalmology. In our first post, we explored how the withdrawal of samples for branded medications used perioperatively will affect prescribing patterns. In our second post, we looked at the economics of generic medications, particularly for Medicare beneficiaries.
Now, let's talk about efficacy. Many eye surgeons around the country are moving toward generic medications for preoperative and postoperative treatment because of cost pressures from patients. In an ideal world, generic equivalents could perform the same job as branded medications for a fraction of the cost.
With this assumption in mind, and with the hope of lowering out-of-pocket costs to our patients, my own practice, Harvard Eye Associates in Laguna Hills, Calif., made a change about 18 months ago to an all-generic regimen for cataract surgery consisting of generic 0.3% ofloxacin, generic prednisolone acetate 1% and generic ketorolac 0.5%. Compared with our previous regimen of all-branded medications — Zymar (gatifloxacin 0.3%, Allergan), Durezol (difluprednate ophthalmic emulsion 0.05%, Alcon) and Xibrom (bromfenac ophthalmic solution 0.09%, Ista Pharmaceuticals), all twice daily — we knew we would lose some efficacy simply because of patient compliance going from a twice-a-day to a four-times-a-day regimen. We did not expect this to affect our clinical outcomes, however.
The generics were simply not equivalent.
Fortunately, we had no increase in infections relative to the prior period using branded medications. In other words, our anti-infective regimen, including topical Betadine (povidone iodine, Purdue Pharma) at the conclusion of surgery, seemed to do its job.
Inflammatory sequelae of surgery, though, occurred at a noticeably increased incidence with the generic regimen. Fortunately, relatively few patients had full-blown cystoid macular edema. However, prolonged postoperative uveitis occurred much more frequently with the generic medication. Patients frequently had to be switched to branded steroids and non-steroidals, and their experience with cataract surgery was clearly affected by this adverse event.
In our practice of four busy cataract surgeons, we learned a clear lesson from this: The term "generic equivalent" is an oxymoron. Since the beginning of 2011, we have switched back to a new branded regimen consisting now of Vigamox (moxifloxacin 0.3%, Alcon) four times a day, non-generic Pred Forte (prednisolone acetate 1%, Allergan) and Bromday (bromfenac 0.09%, Ista Pharmaceuticals) once daily.
We have further learned the following about generic medications:
- The FDA approval process for generic medications requires proof of bioequivalence. In other words, generic drugs must demonstrate similar concentrations of active ingredients. However, bioavailability in target tissues is not tested. Clinical studies on neither animals nor humans are conducted to demonstrate safety or efficacy.
- Inactive ingredients in generic medications may vary widely from their branded counterparts. In an ingested pill, this may not make as much difference as in an eye drop. Toxicity of those incipient ingredients on the eye is commonly seen and has been reported widely, although anecdotally.
- In the case of steroids and non-steroidals after cataract surgery and glaucoma medications, patients may be using these generic products and exposed to these toxic inactive ingredients for many weeks.
While we still firmly believe that generic medications have an important place in the treatment of patients, we now use them more selectively for situations in which we are less concerned about efficacy and tolerability. Our patients are doing much better with the branded regimen that we now use. Inflammatory complications of cataract surgery are virtually unseen. (We are preparing data for a peer-reviewed publication on our experience so that others may learn from it.)
As the economic climate of health care in our country continues to evolve, so too will our challenges as physicians trying to navigate the ever more complex landscape while protecting our patients from harm.
- Disclosure: Dr. Hovanesian is a consultant for Allergan and Ista Pharmaceuticals.