KIAWAH ISLAND, S.C. — Systemic and ophthalmic generics are perceived to be less expensive than brand name medications, but one surgeon speaking here cautioned that the savings may not justify the risks.
In a presentation at Kiawah Eye 2012, Keith A. Walter, MD, discussed three examples of ophthalmic therapeutics whose generic equivalents he believes should not be used: latanoprost, prednisolone acetate and NSAIDs.
Several issues make generic ophthalmic drops different from systemic medications, according to Dr. Walter. First, there is no assay for ophthalmic drugs as there is for systemic drugs.
“Additionally, ophthalmic generics can have different bottle size, tip size, pH, buffers, solubility, etc., which may influence drug delivery, dosage efficacy and toxicity,” he said.
In the case of prednisolone acetate, the particle size is four times larger in the generic version than in the brand name solution, which has led to precipitates and clumping that diminish delivery and absorption in the eye, he said. This has already had real-world impact in DSAEK graft rejections, and it has led to cases of uncontrolled uveitis.
Regarding latanoprost, Dr. Walter cited a study that showed a 4.3% decrease in IOP when patients were switched from generic latanoprost to Xalatan (latanoprost 0.005%, Pfizer) and a 9% increase when they were switched from Xalatan to the generic.
With three generic NSAIDs back on the market, all have shown adverse corneal effects, with several cases of corneal melt and perforation, Dr. Walter said.
Even if physicians write “do not substitute” on their prescriptions, pharmacies merely need to ask permission of the patient to switch to a generic, and pharmacies are incentivized to dispense generics over branded medications, he said.
In June 2011, the U.S. Supreme Court ruled that generic drug manufacturers cannot be held liable for adverse events, while branded drug manufacturers still can, Dr. Walter noted.
He recommended that physicians spend extra time explaining the difference to patients without being judgmental, advising them that it is worth the additional cost. The extra time spent will lead to fewer call-backs, happier patients and more referrals, he said.
Disclosure: Dr. Walter is a consultant for Ista Pharmaceuticals.